The burden of community-managed acute respiratory infections in the first 2-years of life

Factors Associated With Prolonged Respiratory Virus Detection From Polymerase Chain Reaction of Nasal Specimens Collected Longitudinally in Healthy Children in a US Birth Cohort

BACKGROUND

Respiratory viral shedding is incompletely characterized by existing studies due to the lack of longitudinal nasal sampling and limited inclusion of healthy/asymptomatic children. We describe characteristics associated with prolonged virus detection by polymerase chain reaction (PCR) in a community-based birth cohort.

METHODS

Children were followed from birth to 2 years of age in the PREVAIL cohort. Weekly nasal swabs were collected and tested using the Luminex Respiratory Pathogen Panel. Weekly text surveys were administered to ascertain the presence of acute respiratory illnesses defined as fever and/or cough. Maternal reports and medical chart abstractions identified healthcare utilization. Prolonged virus detection was defined as a persistently positive test lasting ≥4 weeks. Factors associated with prolonged virus detection were assessed using mixed effects multivariable logistic regression.

RESULTS

From a sub-cohort of 101 children with ≥70% weekly swabs collected, a total of 1489 viral infections were detected. Prolonged virus detection was found in 23.4% of viral infections overall, 39% of bocavirus infections, 33% of rhinovirus/enterovirus infections, 14% of respiratory syncytial virus (RSV) A infections, and 7% of RSV B infections. No prolonged detection was found for influenza virus A or B, coronavirus 229E or HKU1, and parainfluenza virus 2 or 4 infections. First-lifetime infection with each virus, and co-detection of another respiratory virus were significantly associated with prolonged detection, while symptom status, child sex, and child age were not.

CONCLUSIONS

Prolonged virus detection was observed in 1 in 4 viral infections in this cohort of healthy children and varied by pathogen, occurring most often for bocavirus and rhinovirus/enterovirus. Evaluating the immunological basis of how viral co-detections and recurrent viral infections impact duration of virus detection by PCR is needed to better understand the dynamics of prolonged viral shedding.

Pragmatic Adaptive Trial for Respiratory Infection in Children (PATRIC) Clinical Registry protocol

INTRODUCTION

Acute respiratory infections (ARI) are the most common cause of paediatric hospitalisation. There is an urgent need to address ongoing critical knowledge gaps in ARI management. The Pragmatic Adaptive Trial for Respiratory Infections in Children (PATRIC) Clinical Registry will evaluate current treatments and outcomes for ARI in a variety of paediatric patient groups. The registry will provide a platform and data to inform a number of PATRIC clinical trials, testing various interventions in ARI treatment and management to optimise paediatric ARI care.

METHODS AND ANALYSIS

The PATRIC Clinical Registry is a single-centre, prospective observational registry recruiting from a tertiary paediatric Emergency Department in Western Australia. Through characterising demographic, clinical, treatment and outcome data, the PATRIC Clinical Registry will improve our understanding of antibiotic utilisation and ARI outcomes in children.

ETHICS AND DISSEMINATION

The PATRIC Clinical Registry is conducted in accordance with the Declaration of Helsinki, and the International Council for Harmonisation (ICH) Guidelines for Good Clinical Practice (CPMP/ICH/13595) July 1996. Approval is provided by the Child and Adolescent Health Service Human Research Ethics Committee (HREC). Study results will be communicated by presentation and publication (HREC: RGS0000003078.) TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12619000903189. UTN: U1111-1231-3365.

Association of rhinovirus and potentially pathogenic bacterial detections in the first 3 months of life with subsequent wheezing in childhood

OBJECTIVE

Airway interactions between viruses, especially rhinoviruses, and potentially pathogenic bacteria (PPB; Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis) in early infancy may increase the risk of subsequent wheezing and asthma. We evaluated the association between rhinovirus and PPB in the first 3 months of life and wheezing episodes before age 2 years and asthma at age 5-7 years.

METHODS

An Australian community-based birth cohort of healthy children involved parents collecting nasal swabs weekly and completing symptom diaries daily until age 2 years. In a follow-up subset, asthma diagnosis was assessed annually until age 7 years. Swabs were analyzed by real-time polymerase chain reaction assays. Children were included if they returned symptom diaries beyond age 3 months (wheeze) or were reviewed at age 5-7 years (asthma).

RESULTS

1440 swabs were returned by 146 children in the first 3 months of life. Wheeze and asthma outcomes were recorded for 146 and 84 children, respectively. Each additional week of rhinovirus detection increased the incidence of wheezing before age 2 years by 1.16 times (95% confidence interval [CI]: 0.99-1.35). There were no significant associations between bacteria and wheeze. Each additional week with H. influenzae increased the odds of asthma at age 5-7 years by 135% (odds ratio: 2.35, 95% CI: 0.99-5.58). No significant interaction was observed between rhinovirus and PPB for wheezing or asthma.

CONCLUSION

Early life rhinovirus infection was associated with wheezing before age 2 years and H. influenzae with asthma by age 5-7 years. Microbes may play an etiologic role in wheezing and asthma, warranting further study.

Assessment of the detection accuracy of SARS-CoV-2 rapid antigen test in children and adolescents: An updated meta-analysis

BACKGROUND

Real-time and appropriate antigen tests play a pivotal role in preventing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. However, a previous meta-analysis reported that the antigen test had lower sensitivity for the detection of SARS-CoV-2 in children. To provide a comprehensive evaluation of diagnostic efficiency, we performed an updated meta-analysis to assess the detection accuracy of SARS-CoV-2 antigen tests stratified by days after symptom onset and specimen type in children and adolescents.

METHODS

We comprehensively searched for appropriate studies in the PubMed, Embase, and Cochrane Library databases. Studies on the diagnostic accuracy of antigen tests for SARS-CoV-2 in children and adolescents were included. The relevant data of the included studies were extracted to construct a 2 × 2 table on a per-patient basis. The overall sensitivity and specificity of the SARS-CoV-2 antigen tests were estimated using a bivariate random-effects model.

RESULTS

Seventeen studies enrolling 10 912 patients were included in the present meta-analysis. For the detection accuracy of SARS-CoV-2 antigen tests, the meta-analysis generated a pooled sensitivity of 77.9% (95% confidence interval [CI]: 67.3%-85.8%) and a pooled specificity of 99.6% (95% CI: 98.9%-99.8%). The subgroup analysis of studies that examined antigen tests in symptomatic participants ≦7 days after symptom onset generated a pooled sensitivity of 79.4% (95% CI: 47.6%-94.2%) and a pooled specificity of 99.4% (95% CI: 98.2%-99.8%). Another subgroup analysis of studies that evaluated nasal swab specimens demonstrated a pooled sensitivity of 80.1% (95% CI: 65.0%-89.7%) and a pooled specificity of 98.5% (95% CI: 97.3%-9.2%).

CONCLUSION

Our findings demonstrated that the antigen test performed using nasal swab specimens exhibited high sensitivity for the detection of SARS-CoV-2 within 7 days after symptom onset. Therefore, antigen testing using nasal swabs may be effective in blocking SARS-CoV-2 transmission in children.

Effect of infection control education program on childcare educator knowledge and confidence

ISSUE ADDRESSED

Childcare educator knowledge gaps in infection control practices and outbreak management. This can contribute to the well-reported issue of transmission of infectious diseases in childcare centres and the associated health and economic costs.

METHODS

A health promotion program in the form of an educational slideshow presentation with interactive question/answer component was developed and offered to all childcare centre staff in the Wide Bay region, Queensland.

RESULTS

Childcare educators who participated in the education sessions reported a significant increase in their knowledge and confidence in outbreak management on pre- and post-intervention self-assessment.

CONCLUSIONS

Simple educational programs can significantly improve the self-assessed knowledge and confidence of childcare educators in managing infectious diseases. SO WHAT?: Improving knowledge and confidence of childcare centre staff in managing basic infectious diseases can help reduce the health and economic impacts of these infections. Simple educational health promotion programs could be introduced as part of an orientation program for new staff, or refreshers for existing staff.

Burden of Respiratory Viruses in Children Less Than 2 Years Old in a Community-based Longitudinal US Birth Cohort

BACKGROUND

Respiratory viral infections are a major cause of morbidity and hospitalization in young children. Nevertheless, the population burden of respiratory viral infections, especially asymptomatic cases, is not known due to the lack of prospective community-based cohort studies with intensive monitoring.

METHODS

To address this gap, we enacted the PREVAIL cohort, a Centers for Disease Control and Prevention-sponsored birth cohort in Cincinnati, Ohio, where children were followed from 0 to 2 years of age. Weekly text surveys were administered to record acute respiratory illnesses (ARIs), which were defined as the presence of cough or fever (≥38°C). Weekly midturbinate nasal swabs were collected and tested using the Luminex Respiratory Pathogen Panel, which detected 16 viral pathogens. Viral infection was defined as ≥1 positive tests from the same virus or viral subtype ≤30 days of a previous positive test. Maternal report and medical chart abstractions identified healthcare utilization.

RESULTS

From 4/2017 to 7/2020, 245 mother-infant pairs were recruited and followed. From the 13 781 nasal swabs tested, a total of 2211 viral infections were detected, of which 821 (37%) were symptomatic. Children experienced 9.4 respiratory viral infections/child-year; half were rhinovirus/enterovirus. Viral ARI incidence was 3.3 episodes/child-year. Emergency department visits or hospitalization occurred with only 15% of respiratory syncytial virus infections, 10% of influenza infections, and only 4% of all viral infections. Regardless of pathogen, most infections were asymptomatic or mild.

CONCLUSIONS

Respiratory viral infections are common in children 0-2 years. Most viral infections are asymptomatic or non-medically attended, underscoring the importance of community-based cohort studies.

Efficacy of nirsevimab against respiratory syncytial virus lower respiratory tract infections in preterm and term infants, and pharmacokinetic extrapolation to infants with congenital heart disease and chronic lung disease: a pooled analysis of randomised controlled trials

BACKGROUND

In a phase 2b trial and the phase 3 MELODY trial, nirsevimab, an extended half-life, monoclonal antibody against respiratory syncytial virus (RSV), protected healthy infants born preterm or at full term against medically attended RSV lower respiratory tract infection (LRTI). In the MEDLEY phase 2-3 trial in infants at higher risk for severe RSV infection, nirsevimab showed a similar safety profile to that of palivizumab. The aim of the current analysis was to assess the efficacy of nirsevimab using a weight-banded dosing regimen in infants born between 29 weeks gestational age and full term.

METHODS

Infants enrolled in the phase 2b and MELODY trials were randomised (2:1) to receive a single intramuscular injection of nirsevimab (infants weighing <5 kg received 50 mg; those weighing ≥5 kg received 100 mg) or placebo before the RSV season. Infants in MEDLEY were randomised (2:1) to receive one dose of nirsevimab (infants weighing <5 kg received 50 mg; those weighing ≥5 kg received 100 mg) followed by four monthly placebo doses, or five once-a-month intramuscular doses of palivizumab. We report a prespecified pooled efficacy analysis assessing the weight-banded dosing regimen proposed on the basis of the phase 2b and MELODY trials, in addition to extrapolated efficacy in infants with chronic lung disease, congenital heart disease, or extreme preterm birth (<29 weeks' gestational age) based on pharmacokinetic data from the phase 2-3 MEDLEY safety trial. For the pooled efficacy analysis, the primary endpoint was incidence of medically attended RSV LRTI through 150 days post-dose. The secondary efficacy endpoint was number of admissions to hospital for medically attended RSV LRTI. The incidence of very severe RSV LRTI was an exploratory endpoint, defined as cases of hospital admission for medically attended RSV LRTI that required supplemental oxygen or intravenous fluids. We also did a prespecified exploratory analysis of medically attended LRTI of any cause (in the investigator's judgement) and hospital admission for respiratory illness of any cause (defined as any upper respiratory tract infection or LRTI leading to hospital admission). Post hoc exploratory analyses of outpatient visits and antibiotic use were also done. Nirsevimab serum concentrations in MEDLEY were assessed using population pharmacokinetic methods and the pooled data from the phase 2b and MELODY trials. An exposure target was defined on the basis of an exposure-response analysis. To successfully demonstrate extrapolation, more than 80% of infants in MEDLEY had to achieve serum nirsevimab exposures at or above the predicted efficacious target.

FINDINGS

Overall, 2350 infants (1564 in the nirsevimab group and 786 in the placebo group) in the phase 2b and MELODY trials were included in the pooled analysis. Nirsevimab showed efficacy versus placebo with respect to the primary endpoint of medically attended RSV LRTI (19 [1%] nirsevimab recipients vs 51 [6%] placebo recipients; relative risk reduction [RRR] 79·5% [95% CI 65·9-87·7]). Consistent efficacy was shown for additional endpoints of RSV LRTI hospital admission (nine [1%] nirsevimab recipients vs 21 [3%] placebo recipients; 77·3% [50·3-89·7]) and very severe RSV (five [<1%] vs 18 [2%]; 86·0% [62·5-94·8]). Nirsevimab recipients had fewer hospital admissions for any-cause respiratory illness (RRR 43·8% [18·8-61·1]), any-cause medically attended LRTI (35·4% [21·5-46·9]), LRTI outpatient visits (41·9% [25·7-54·6]), and antibiotic prescriptions (23·6% [3·8-39·3]). Among infants with chronic lung disease, congenital heart disease, or extreme preterm birth in MEDLEY, nirsevimab serum exposures were similar to those found in the pooled data; exposures were above the target in more than 80% of the overall MEDLEY trial population (94%), including infants with chronic lung disease (94%) or congenital heart disease (80%) and those born extremely preterm (94%).

INTERPRETATION

A single dose of nirsevimab protected healthy infants born at term or preterm from medically attended RSV LRTI, associated hospital admission, and severe RSV. Pharmacokinetic data support efficacy extrapolation to infants with chronic lung disease, congenital heart disease, or extreme prematurity. Together, these data suggest that nirsevimab has the potential to change the landscape of infant RSV disease by reducing a major cause of infant morbidity and the consequent burden on caregivers, clinicians, and health-care providers.

FUNDING

AstraZeneca and Sanofi.

Influence of Respiratory Tract Infections on Vocabulary Growth in Relation to Child's Sex: The STEPS Study

Common health issues have been less examined in studies of early language development, particularly in relation to the child's sex. Respiratory tract infections, often complicated by acute otitis media, are common in children during the first years of life, when early vocabulary development takes place. The present study, conducted in Finland, aimed to investigate whether possible associations between recurrent respiratory tract infections, background factors, and vocabulary growth differ in boys and girls aged 13 to 24 months. The participants (N = 462, 248 boys and 214 girls) were followed for respiratory tract infections and acute otitis media from 0 to 23 months of age. The parents completed daily symptom diaries of respiratory symptoms, physician visits, and diagnoses. The expressive vocabulary was measured with parental reports. We found that recurrent respiratory tract infections were not associated with slower vocabulary development in boys or girls. In fact, boys with recurrent respiratory tract infections had more vocabulary growth during the second year than boys who were less sick. We found that vocabulary growth was associated differently with respiratory tract infections and background factors as a function of the child's sex. The vocabulary growth of boys seems to be more influenced by environmental factors than that of girls.

Performance of the Sofia SARS-CoV-2 Rapid Antigen Test in Symptomatic and Asymptomatic Pediatric Patients

The sensitivity and specificity of SARS-CoV-2 antigen tests have not been widely assessed in children. We evaluated children presenting to outpatient care with Quidel Sofia SARS-CoV-2 antigen test (Sofia-Ag-RDT) compared against Cepheid Xpert Xpress SARS-CoV-2/Flu/RSV reverse transcriptase-polymerase chain reaction test from November 2020 to April 2021. Sofia-Ag-RDT had the highest sensitivity in symptomatic (82%; 95% confidence interval, 68%-91%) children.

Incidence of lower respiratory tract infection and associated viruses in a birth cohort in the Philippines

Background

Lower respiratory tract infection (LRTI) is an important cause of morbidity and mortality in infants and young children. However, the etiological role of viruses and the timing of developing LRTI are not well defined.

Methods

We analyzed the data of a prospective cohort study in the Philippines as a birth cohort. We detected LRTI among children who visited healthcare facilities with respiratory symptom, and collected nasopharyngeal swabs for virus detection. We analyzed the incidence rates (IRs) and cumulative proportion of LRTI and severe LRTI by age group and each virus detected.

Results

A total of 350 LRTI episodes were observed from 473 child-years yielded from 419 children. The IRs of LRTI were 70.8, 70.7, and 80.8 per 100 child-years for 0–5, 6–11, and 12–23 months of age, respectively. By 12 months of age, 45% of children developed LRTI at least once. Rhinovirus and respiratory syncytial virus were the most frequently detected viruses in all age groups. However, the IRs of influenza virus were low especially at 0–5 months of age.

Conclusions

We identified various patterns of age-specific IRs of LRTI and severe LRTI for different viruses, which should be considered to establish more effective interventions including vaccinations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07289-3.

Association between vaccination status, symptom identification and healthcare use: Implications for test negative design observational studies

AIM

To test the internal validity of the test-negative design (TND) by investigating associations between maternal influenza vaccination, and new virus detection episodes (VDEs), acute respiratory illness, and healthcare visits in their children.

METHODS

Eighty-five children from a birth cohort provided daily symptoms, weekly nasal swabs, and healthcare use data until age 2-years. Effect estimates are summarised as incidence rate ratios (IRR).

RESULTS

There was no association between maternal vaccination and VDEs in children (IRR = 1.1; 95 %CI = 0.9-1.2). Influenza-vaccinated mothers were more likely than unvaccinated mothers to both report, and seek healthcare for, acute lower respiratory illness in their children, IRR = 2.4; 95 %CI = 1.2-4.8 and IRR = 2.2; 95 %CI = 1.1-4.3, respectively.

CONCLUSION

A key assumption of the TND, that healthcare seeking behaviour for conditions of the same severity is not associated with vaccine receipt, did not hold. Further studies of the performance of the TND in different populations are required to confirm its validity.

Birth cohort studies using symptom diaries for assessing respiratory diseases–a scoping review

Background

Respiratory infections are the most frequent health problem in childhood leading to morbidity and socioeconomic burden. Studying symptoms of respiratory infections in home based settings requires dedicated prospective cohort studies using diaries. However, no information is available on which birth cohort studies using symptom diary data. A review of birth cohort studies with available symptom diary data, follow-up data, and bio samples is needed to support research collaborations and create potential synergies.

Methods

We conducted a scoping review of birth cohort studies using diaries for the collection of respiratory symptoms. The scoping review was conducted in accordance with the PRISMA Extension. We searched the electronic databases PubMed, Embase, Web of science and CINAHL (last search November 2020) resulting in 5872 records (based on title and abstract screening) eligible for further screening.

Results

We examined 735 records as full text articles and finally included 57 according to predefined inclusion criteria. We identified 22 birth cohort studies that collect(ed) data on respiratory symptoms using a symptom diary starting at birth. Numbers of participants ranged from 129 to 8677. Eight studies collected symptom diary information only for the first year of life, nine for the first two years or less and six between three and six years. Most of the cohorts collected biosamples (n = 18) and information on environmental exposures (n = 19).

Conclusion

Information on respiratory symptoms with daily resolution was collected in several birth cohorts, often including related biosamples, and these data and samples can be used to study full spectrum of infections, particularly including those which did not require medical treatment.

Efficacy of Digital Health Tools for a Pediatric Patient Registry: Semistructured Interviews and Interface Usability Testing With Parents and Clinicians

Background

Acute respiratory infection (ARI) in childhood is common, but more knowledge on the burden and natural history of ARI in the community is required. A better understanding of ARI risk factors, treatment, and outcomes will help support parents to manage their sick child at home. Digital health tools are becoming more widely adopted in clinical care and research and may assist in understanding and managing common pediatric diseases, including ARI, in hospitals and in the community. We integrated 2 digital tools—a web-based discharge communication system and the REDCap (Research Electronic Data Capture) platform—into the Pragmatic Adaptive Trial for Acute Respiratory Infection in Children to enhance parent and physician engagement around ARI discharge communication and our patient registry.

Objective

The objective of this study is to determine the efficacy and usability of digital tools integrated into a pediatric patient registry for ARI.

Methods

Semistructured interviews and software interface usability testing were conducted with 11 parents and 8 emergency department physicians working at a tertiary pediatric hospital and research center in Perth, Western Australia, in 2019. Questions focused on experiences of discharge communication and clinical trial engagement. Responses were analyzed using the qualitative Framework Method. Participants were directly observed using digital interfaces as they attempted predetermined tasks that were then classified as success, failure, software failure, or not observed. Participants rated the interfaces using the System Usability Scale (SUS).

Results

Most parents (9/11, 82%) indicated that they usually received verbal discharge advice, with some (5/11, 45%) recalling receiving preprinted resources from their physician. Most (8/11, 73%) would also like to receive discharge advice electronically. Most of the physicians (7/8, 88%) described their usual practice as verbal discharge instructions, with some (3/8, 38%) reporting time pressures associated with providing discharge instructions. The digital technology option was preferred for engaging in research by most parents (8/11, 73%). For the discharge communication digital tool, parents gave a mean SUS score of 94/100 (SD 4.3; A grade) for the mobile interface and physicians gave a mean usability score of 93/100 (SD 4.7; A grade) for the desktop interface. For the research data management tool (REDCap), parents gave a mean usability score of 78/100 (SD 11.0; C grade) for the mobile interface.

Conclusions

Semistructured interviews allowed us to better understand parent and physician experiences of discharge communication and clinical research engagement. Software interface usability testing methods and use of the SUS helped us gauge the efficacy of our digital tools with both parent and physician users. This study demonstrates the feasibility of combining qualitative research methods with software industry interface usability testing methods to help determine the efficacy of digital tools in a pediatric clinical research setting.

Symptom Burden and Factors Associated with Acute Respiratory Infections in the First Two Years of Life-Results from the LoewenKIDS Cohort

Acute respiratory infections (ARIs) are the most common childhood illnesses worldwide whereby the reported frequency varies widely, often depending on type of assessment. Symptom diaries are a powerful tool to counteract possible under-reporting, particularly of milder infections, and thus offer the possibility to assess the full burden of ARIs. The following analyses are based on symptom diaries from participants of the German birth cohort study LoewenKIDS. Primary analyses included frequencies of ARIs and specific symptoms. Factors, which might be associated with an increased number of ARIs, were identified using the Poisson regression. A subsample of two hundred eighty-eight participants were included. On average, 13.7 ARIs (SD: 5.2 median: 14.0 IQR: 10-17) were reported in the first two years of life with an average duration of 11 days per episode (SD: 5.8, median: 9.7, IQR: 7-14). The median age for the first ARI episode was 91 days (IQR: 57-128, mean: 107, SD: 84.5). Childcare attendance and having siblings were associated with an increased frequency of ARIs, while exclusive breastfeeding for the first three months was associated with less ARIs, compared to exclusive breastfeeding for a longer period. This study provides detailed insight into the symptom burden of ARIs in German infants.

The Influence of FUT2 and FUT3 Polymorphisms and Nasopharyngeal Microbiome on Respiratory Infections in Breastfed Bangladeshi Infants from the Microbiota and Health Study

Acute respiratory infections (ARIs) are one of the most common causes of morbidity and mortality in young children. The aim of our study was to examine whether variation in maternal FUT2 (α1,2-fucosyltransferase 2) and FUT3 (α1,3/4-fucosyltransferase 3) genes, which shape fucosylated human milk oligosaccharides (HMOs) in breast milk, are associated with the occurrence of ARIs in breastfed infants as well as the influence of the nasopharyngeal microbiome on ARI risk. Occurrences of ARIs were prospectively recorded in a cohort of 240 breastfed Bangladeshi infants from birth to 2 years. Secretor and Lewis status was established by sequencing of FUT2/3 genes. The nasopharyngeal microbiome was characterized by shotgun metagenomics, complemented by specific detection of respiratory pathogens; 88.6% of mothers and 91% of infants were identified as secretors. Maternal secretor status was associated with reduced ARI incidence among these infants in the period from birth to 6 months (incidence rate ratio [IRR], 0.66; 95% confidence interval [CI], 0.47 to 0.94; P = 0.020), but not at later time periods. The nasopharyngeal microbiome, despite precise characterization to the species level, was not predictive of subsequent ARIs. The observed risk reduction of ARIs among infants of secretor mothers during the predominant breastfeeding period is consistent with the hypothesis that fucosylated oligosaccharides in human milk contribute to protection against respiratory infections. However, we found no evidence that modulation of the nasopharyngeal microbiome influenced ARI risk. IMPORTANCE The observed risk reduction of acute respiratory infections (ARIs) among infants of secretor mothers during the predominant breastfeeding period is consistent with the hypothesis that fucosylated oligosaccharides in human milk contribute to protection against respiratory infections. Respiratory pathogens were only weak modulators of risk, and the nasopharyngeal microbiome did not influence ARI risk, suggesting that the associated protective effects of human milk oligosaccharides (HMOs) are not conveyed via changes in the nasopharyngeal microbiome. Our observations add to the evidence for a role of fucosylated HMOs in protection against respiratory infections in exclusively or predominantly breastfed infants in low-resource settings. There is no indication that the nasopharyngeal microbiome substantially modulates the risk of subsequent mild ARIs. Larger studies are needed to provide mechanistic insights on links between secretor status, HMOs, and risk of respiratory infections.

Child Care Center Hand Hygiene Programs' Cost-Effectiveness in Preventing Respiratory Infections

BACKGROUND

We previously demonstrated that a hand hygiene program, including hand sanitizer and educational measures, for day care center (DCC) staff, children, and parents was more effective than a soap-and-water program, with initial observation, in preventing respiratory infections (RIs) in children attending DCCs. We analyzed the cost-effectiveness of these programs in preventing RIs.

METHODS

A cluster, randomized, controlled and open study of 911 children aged 0 to 3 years, attending 24 DCCs in Almeria. Two intervention groups of DCC-families performed educational measures and hand hygiene, one with soap-and-water (SWG) and another with hand sanitizer (HSG). The control group (CG) followed usual hand-washing procedures. RI episodes, including symptoms, treatments, medical contacts, complementary analyses, and DCC absenteeism days, were reported by parents. A Bayesian cost-effectiveness model was developed.

RESULTS

There were 5201 RI episodes registered. The adjusted mean societal costs of RIs per child per study period were CG: €522.25 (95% confidence interval [CI]: 437.10 to 622.46); HSG: €374.53 (95% CI: 314.90 to 443.07); SWG: €494.51 (95% CI: 419.21 to 585.27). The indirect costs constituted between 35.7% to 43.6% of the total costs. Children belonging to the HSG had an average of 1.39 fewer RI episodes than the CG and 0.93 less than the SWG. It represents a saving of societal cost mean per child per study period of €147.72 and €119.15, respectively. The HSG intervention was dominant versus SWG and CG.

CONCLUSIONS

Hand hygiene programs that include hand sanitizer and educational measures for DCC staff, children, and parents are more effective and cost less than a program with soap and water and initial observation in children attending DCCs.

Cord-blood respiratory syncytial virus antibodies and respiratory health in first 5 years of life

OBJECTIVE

To determine the potential longer-term effects of maternal antenatal respiratory syncytial virus (RSV) vaccination, we examined the association between cord-blood RSV-neutralizing antibodies (RSV-NA) and RSV infections in the first 2 years of life, RSV-NA at 3 years, and respiratory health to age 5 years.

METHODS

Two community-based Australian birth cohorts were combined. For children with at least one atopic parent, paired serum RSV-NA levels were compared in cord blood and at age 3 years. Weekly nasal swabs were collected in one cohort and during acute respiratory infections (ARI) in the other. Wheeze history up to age 5 years and physician-diagnosed asthma at 5 years was collected by parent report.

RESULTS

In 264 children, each log₁₀ increase of cord-blood RSV-NA level was associated with 37% decreased risk (adjusted incidence-rate-ratio [aIRR] 0.63; 95% confidence interval [CI]: 0.40-1.01) of RSV-ARI and 49% decreased risk (aIRR 0.51; 95% CI: 0.25-1.02) of RSV acute lower respiratory infections (ALRI) at 12-24 months of age. However, higher cord-blood RSV-NA was associated with increased risk of all-cause ALRI (aIRR 1.29; 95% CI: 0.99-1.69), wheeze-associated ALRI (aIRR 1.75; 95% CI: 1.08-2.82), and severe ALRI (aIRR 2.76; 95% CI: 1.63-4.70) at age 6-<12 months. Cord-blood RSV-NA was not associated with RSV-ARI in the first 6-months, RSV-NA levels at 3 years, or wheeze or asthma at 5 years.

CONCLUSIONS

Higher levels of cord-blood RSV-NA did not protect against RSV infections during the first 6-months-of-life, time-to-first RSV-ARI, or wheeze or asthma in the first 5 years of life. Additional strategies to control RSV-related illness in childhood are needed.

Early-Life Respiratory Infections in Infants with Cow's Milk Allergy: An Expert Opinion on the Available Evidence and Recommendations for Future Research

Acute respiratory infections are a common cause of morbidity in infants and young children. This high rate of respiratory infections in early life has a major impact on healthcare resources and antibiotic use, with the associated risk of increasing antibiotic resistance, changes in intestinal microbiota composition and activity and, consequently, on the future health of children. An international group of clinicians and researchers working in infant nutrition and cow's milk allergy (CMA) met to review the available evidence on the prevalence of infections in healthy infants and in those with allergies, particularly CMA; the factors that influence susceptibility to infection in early life; links between infant feeding, CMA and infection risk; and potential strategies to modulate the gut microbiota and infection outcomes. The increased susceptibility of infants with CMA to infections, and the reported potential benefits with prebiotics, probiotics and synbiotics with regard to improving infection outcomes and reducing antibiotic usage in infants with CMA, makes this a clinically important issue that merits further research.

Epidemiology of respiratory syncytial virus in a community birth cohort of infants in the first 2 years of life

Respiratory syncytial virus (RSV) is the most common virus identified in children hospitalised with acute respiratory infections. However, less is known about RSV in community settings. This report describes RSV epidemiology in the community, including acute illness episodes, healthcare burden, and risk factors in Australian children during the first 2-years of life. A community-based, birth cohort from Brisbane, Australia, followed children until their second birthday. Parents completed daily respiratory symptom and illness-burden diaries. Weekly parent-collected nasal swabs were analysed for RSV by real-time polymerase chain reaction assays. Serum RSV-neutralising antibodies were assayed at age 3 years. Overall, 158 children provided 11,216 swabs, of which 104 were RSV-positive (85 incident episodes). RSV incidence in the first 2 years of life was 0.46 (95% CI = 0.37-0.58) episodes per child-year. Incidence increased with age and formal childcare attendance and was highest in autumn. Of 82 episodes linked with symptom data, 60 (73.2%) were symptomatic, 28 (34.1%) received community-based medical care, and 2 (2.4%) led to hospitalisation. Viral load was higher in symptomatic than asymptomatic infections. In 72 children, RSV-specific antibody seroprevalence was 94.4% at age 3 years.Conclusion: RSV incidence increased after age 6-months with approximately three-quarters of infections symptomatic and most infections treated in the community. What is known •RSV is a major cause of hospitalisation for acute lower respiratory infections in infants and young children, especially in the first 6 months of life. •However, limited data exist on the overall burden in young children at the community level. What is new •RSV incidence in the community increases after age 6 months, and by 3 years, most children have been infected. •About one-quarter of RSV infections were asymptomatic in children aged < 2 years, and approximately 60% of children with RSV-related symptoms had a healthcare contact of any kind with most managed within the community.

Medication and healthcare use, parent knowledge and cough in children: A cohort study

INTRODUCTION

Cough is an important contributor to the health burden of children and their families. There are limited data describing healthcare utilization and medication use over the course of a cough illness beyond the initial presentation. Our primary objective was to describe medication and healthcare use in children with a respiratory illness with cough as a symptom over the course of the illness.

METHODS

A cohort study of children aged less than 15-years presenting to three primary healthcare centers and three emergency departments with a cough illness between July 7, 2015 and October 6, 2018. Children with immunosuppression, known chronic lung diseases (except asthma) and those requiring hospitalization at screening were excluded. The primary outcomes were cough-related frequency and type of healthcare seeking and medication use up to 28 days following enrolment.

RESULTS

Data for 465 children were analyzed; median age 2.2-years (interquartile range = 1.1-5.3). Cough at Day 28 persisted in 117 children (25.2%). Overall, 436 (94%) children received medications in the week before and/or 4 weeks following enrolment. Half with upper respiratory tract infections were prescribed antibiotics. Among children with no diagnosis of asthma, reactive airways disease or croup (n = 404), 16.8% were given steroids. Fifty-eight percent of children sought healthcare at least once before their baseline presentation (median = 1, range = 0-20) and 49.7% had at least one further presentation in the following 28 days.

CONCLUSIONS

High healthcare utilization, inappropriate medication use, and suboptimal parent knowledge regarding cough suggests targeted education is needed to improve management and reduce cough burden.

Neonatal BCG vaccination and infections in the first year of life: the MIS BAIR randomised controlled trial

BACKGROUND

Bacille Calmette-Guérin (BCG) vaccination has beneficial off-target effects that may include protecting against non-mycobacterial infectious diseases. We aimed to determine whether neonatal BCG vaccination reduces lower respiratory tract infections (LRTI) in infants in the MIS BAIR trial.

METHODS

In this investigator-blinded trial, neonates in Australia were randomised to receive BCG-Denmark vaccination or no BCG at birth. Episodes of LRTI were determined by symptoms reported in parent-completed 3-monthly questionnaires over the first year of life. Data were analysed by intention-to-treat using binary regression. Clinicaltrials.gov (NCT01906853).

RESULTS

From August 2013 to September 2016, 1272 neonates were randomised to the BCG vaccination (n=637) or control (n=635) group. The proportion of participants with an episode of LRTI in the first year of life among BCG-vaccinated infants was 54.8% compared to 58.0% in the control group, resulting in a risk difference of -3.2 (95% CI -9.0 to 2.6) after multiple imputation. There was no interaction observed between the primary outcome and sex, maternal BCG or the other pre-specified effect modifiers.

CONCLUSIONS

Based on the findings of this trial, there is insufficient evidence to support the use of neonatal BCG vaccination to prevent LRTI in the first year of life in high-income settings.

Parechovirus A Infections in Healthy Australian Children During the First 2 Years of Life: A Community-based Longitudinal Birth Cohort Study

Background

Hospital-based studies identify parechovirus (PeV), primarily PeV-A3, as an important cause of severe infections in young children. However, few community-based studies have been published and the true PeV infection burden is unknown. We investigated PeV epidemiology in healthy children participating in a community-based, longitudinal birth cohort study.

Methods

Australian children (n = 158) enrolled in the Observational Research in Childhood Infectious Diseases (ORChID) study were followed from birth until their second birthday. Weekly stool and nasal swabs and daily symptom diaries were collected. Swabs were tested for PeV by reverse-transcription polymerase chain reaction and genotypes determined by subgenomic sequencing. Incidence rate, infection characteristics, clinical associations, and virus codetections were investigated.

Results

PeV was detected in 1423 of 11 124 (12.8%) and 17 of 8100 (0.2%) stool and nasal swabs, respectively. Major genotypes among the 306 infection episodes identified were PeV-A1 (47.9%), PeV-A6 (20.1%), and PeV-A3 (18.3%). The incidence rate was 144 episodes (95% confidence interval, 128–160) per 100 child-years. First infections appeared at a median age of 8 (interquartile range, 6.0–11.7) months. Annual seasonal peaks changing from PeV-A1 to PeV-A3 were observed. Infection was positively associated with age ≥6 months, summer season, nonexclusive breastfeeding at age <3 months, and formal childcare attendance before age 12 months. Sole PeV infections were either asymptomatic (38.4%) or mild (32.7%), while codetection with other viruses in stool swabs was common (64.4%).

Conclusions

In contrast with hospital-based studies, this study showed that diverse and dynamically changing PeV genotypes circulate in the community causing mild or subclinical infections in children.

Parechovirus can cause severe illnesses in children. However, studies focus mainly on hospitalized populations. True disease burden in the community remains largely unknown. From our community-based cohort, we found diverse parechovirus genotypes in the community, causing mild or subclinical infections in children.

Burden of infection in Australian infants

AIM

To determine the incidence, risk factors and health service utilisation for infection in the first 12 months of life in a population-derived Australian pre-birth cohort.

METHODS

The Barwon Infant Study is a population-derived pre-birth cohort with antenatal recruitment (n = 1074) based in Geelong, Victoria, Australia. Infection data were collected by parent report, and general practitioner and hospital records at 1, 3, 6, 9 and 12 months of age. We calculated the incidence of infection, attendance at a health service with infection and used multiple negative binomial regression to investigate the effects of a range of exposures on incidence of infection.

RESULTS

In the first 12 months of life, infections of the upper and lower respiratory tract (henceforth 'respiratory infections'), conjunctivitis and gastroenteritis occurred at a rate of 0.35, 0.04 and 0.04 episodes per child-month, respectively. A total of 482 (72.4%) infants attended a general practitioner with an infection and 69 (10.4%) infants attended the emergency department. Maternal antibiotic exposure in pregnancy and having older siblings were associated with respiratory infection. Childcare attendance by 12 months of age was associated with respiratory infections and gastroenteritis. Breastfeeding, even if less than 4 weeks in total, was associated with reduced respiratory infection.

CONCLUSION

Infection, especially of the respiratory tract, is a common cause of morbidity in Australian infants. Several potentially modifiable risk factors were identified, particularly for respiratory infections. Most infections were managed by general practitioners and 1 in 10 infants attended an emergency department with infection in the first year of life.

Changing Epidemiology of Acute Respiratory Infections in Under-Two Children in Dhaka, Bangladesh

Objectives: Risk factors for acute respiratory infections (ARIs) in community settings are not fully understood, especially in low-income countries. We examined the incidence and risk factors associated with ARIs in under-two children from the Microbiota and Health study. Methods: Children from a peri-urban area of Dhaka (Bangladesh) were followed from birth to 2 years of age by both active surveillance of ARIs and regular scheduled visits. Nasopharyngeal samples were collected during scheduled visits for detection of bacterial facultative respiratory pathogens. Information on socioeconomic, environmental, and household conditions, and mother and child characteristics were collected. A hierarchical modeling approach was used to identify proximate determinants of ARIs. Results: Of 267 infants, 87.3% experienced at least one ARI episode during the first 2 years of life. The peak incidence of ARIs was 330 infections per 100 infant-years and occurred between 2 and 4 months of age. Season was the main risk factor (rainy monsoon season, incidence rate ratio [IRR] 2.43 [1.92-3.07]; cool dry winter, IRR 2.10 [1.65-2.67] compared with hot dry summer) in the first 2 years of life. In addition, during the first 6 months of life, young maternal age (<22 years; IRR 1.34 [1.01-1.77]) and low birth weight (<2,500 g; IRR 1.39 [1.03-1.89]) were associated with higher ARI incidence. Conclusions: Reminiscent of industrialized settings, cool rainy season rather than socioeconomic and hygiene conditions was a major risk factor for ARIs in peri-urban Bangladesh. Understanding the causal links between seasonally variable factors such as temperature, humidity, crowding, diet, and ARIs will inform prevention measures.

Endemic Non-SARS-CoV-2 Human Coronaviruses in a Community-Based Australian Birth Cohort

BACKGROUND AND OBJECTIVES

The coronavirus (CoV) disease 2019 pandemic has drawn attention to the CoV virus family. However, in community settings, there is limited information on these viruses in healthy children. We explored the epidemiology of the 4 endemic (non-severe acute respiratory syndrome CoV 2) human coronaviruses (HCoVs) by species, including acute illness episodes, risk factors, and health care burden in Australian children in the first 2 years of life.

METHODS

The Observational Research in Childhood Infectious Diseases community-based cohort was a prospective study of acute respiratory illnesses in children from birth until their second birthday. Parents recorded daily symptoms, maintained an illness-burden diary, and collected weekly nasal swabs, which were tested for 17 respiratory viruses, including HCoVs, by real-time polymerase chain reaction assays.

RESULTS

Overall, 158 children participating in Observational Research in Childhood Infectious Diseases provided 11 126 weekly swabs, of which 168 were HCoV-positive involving 130 incident episodes. HCoV-NL63 and HCoV-OC43 were most commonly detected, accounting for two-thirds of episodes. Whereas 30 children had different HCoVs detected on different occasions, 7 were reinfected with the same species. HCoV incidence in the first 2 years of life was 0.76 episodes per child-year (95% confidence interval [CI] 0.63 to 0.91), being greatest in the second year (1.06; 95% CI 0.84 to 1.33) and during winter (1.32; 95% CI 1.02 to 1.71). Fifty percent of HCoV episodes were symptomatic, and 24.2% led to health care contact.

CONCLUSIONS

In children, HCoV infections are common, recurrent, and frequently asymptomatic. In future studies, researchers should determine transmission pathways and immune mechanisms.

Parainfluenza Virus Infection in an Australian Community-based Birth Cohort

In a community-based birth cohort of 158 Australian infants followed to age 2 years, the incidence rate of human parainfluenza virus (HPIV) was 0.42 (95% CI = 0.33, 0.54) episodes per child-year with episodes occurring year-round, peaking in the spring season. HPIV-3 was the dominant subtype. Overall, 41% of detections were asymptomatic; only 32% of HPIV episodes led to healthcare contact with 1 hospitalization.

Bacterial colonization dynamics associated with respiratory syncytial virus during early childhood

Respiratory syncytial virus (RSV) is an important cause of early life acute respiratory infections. Potentially pathogenic respiratory bacteria, including Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae are frequently detected during RSV infections and associated with increased illness severity. However, the temporal dynamics of bacterial colonization associated with RSV infection remain unclear. We used weekly nasal swab data from a prospective longitudinal birth cohort in Brisbane, Australia, to investigate bacterial colonization patterns within children aged less than 2 years in the 4-week period before and after an RSV infection. During 54 RSV infection episodes recorded in 47 children, both S. pneumoniae and M. catarrhalis were detected frequently (in 33 [61.1%] and 26 [48.1%] RSV infections, respectively). In most cases, S. pneumoniae and M. catarrhalis colonization preceded the viral infection, with the nasal load of each increasing during RSV infection. Generally, the dominant serotype of S. pneumoniae remained consistent in the 1 to 2 weeks immediately before and after RSV infection. Little evidence was found to indicate that prior colonization with either bacteria predisposed participants to developing RSV infection during the annual seasonal epidemic. Possible coacquisition events, where the bacteria species was first detected with RSV and not in the preceding 4 weeks, were observed in approximately 20% of RSV/S. pneumoniae and RSV/M. catarrhalis codetections. Taken together our results indicate that RSV generally triggered an outgrowth, rather than a new acquisition, of S. pneumoniae and M. catarrhalis from the resident microbial community.

Risk Factors for Chronic Cough in Young Children: A Cohort Study

Background and Objective: Data on the predictors of chronic cough development in young children are scarce. Our primary objective was to examine the factors associated with young children developing a chronic cough, with a focus on childcare attendance. Methods: A secondary analysis of data collected in a prospective cohort study of children presenting to three emergency departments and three primary healthcare centers in southeast Queensland, Australia. Eligible children where those aged <6-years presenting with cough and without known underlying chronic lung disease other than asthma. Children were followed for 4 weeks to ascertain cough duration. The primary outcome was persistent cough at day-28. Logistic regression models were undertaken to identify independent predictors of chronic cough including sensitivity analyses that accounted for children with unknown cough status at day-28. Results: In 362 children, 95 (26.2%) were classified as having chronic cough. In models that included only children for whom cough status was known at day-28, symptom duration at enrolment, age <12 months [adjusted odds ratio (aOR) 4.5, 95% confidence interval (CI) 1.1, 18.7], gestational age (aOR 3.2, 95%CI 1.4, 7.9), underlying medical conditions (aOR 2.6, 95% CI 1.3, 5.5), a history of wheeze (aOR 2.6, 95% CI 1.4, 4.8) and childcare attendance (aOR 2.3, 95% CI 1.2, 4.4) were independent predictors of chronic cough. Amongst childcare attendees only, 64 (29.8%) had chronic cough at day-28. The strongest predictor of chronic cough amongst childcare attendees was continued attendance at childcare during their illness (aOR = 12.9, 95% CI 3.9, 43.3). Conclusion: Gestational age, underlying medical conditions, prior wheeze and childcare attendance are risk factors for chronic cough in young children. Parents/careers need to be aware of the risks associated with their child continuing to attend childcare whilst unwell and childcare centers should reinforce prevention measures in their facilities.

Respiratory Symptoms in Post-infancy Children. A Dutch Pediatric Cohort Study

Aim: To study the pattern of respiratory symptoms in children in the general population. Method: We followed a cohort of children for up to 2 years through parents completing weekly online questionnaires in the Child-Is-Ill study ("Kind-en-Ziekmeting" in Dutch); the study was running 2012-2015. Inclusion criteria were "an ordinary child" (according to the parents) and <18 years old at inclusion. We especially encouraged participation of post-infancy children. Age at inclusion, sex, smoking exposure, allergy in the family, and frequent infections in the family were noted. Pearson's correlation, principal component analysis, latent class analysis, latent profile analysis, linear regression, and linear mixed effects regression were used in the statistical analyses. Results: Data were collected on 55,524 childweeks in 755 children (50% girls; median age, 7 years; interquartile range, 4-11 years, 97% ≥2 years at inclusion), with reported symptom(s) in 8,425 childweeks (15%), leading to school absenteeism in 25%, doctor's visits in 12%, and parental sick leave in 8%; symptoms lasting ≥3 weeks were rare (2% of episodes). Linear mixed effects regression showed significant, but only limited, effects of season on the proportion of "symptom(s) reported" per individual child. Only runny nose showed a significant, but very small, age effect. However, the variability between the children was considerable. There were no obvious subgroups of children with specific symptom combinations. Conclusion: In any randomly chosen week, the vast majority of children (85%) in our-mainly-post-infancy cohort derived from the general population did not have any symptom, even in the younger age group, even in winter. The children showed considerable variability; no clear subgroups of symptom patterns could be identified, underlining the difficult position of healthcare providers. These results support our opinion that post-infancy children in the general population should not be evaluated as if they are infants when they have recurrent respiratory symptoms. If they clearly deviate from the above-described most common pattern, it is wise to keep an eye on potential, maybe even rare, serious underlying causes.

Recall accuracy of weekly automated surveys of health care utilization and infectious disease symptoms among infants over the first year of life

Automated surveys, by interactive voice response (IVR) or email, are increasingly used for clinical research. Although convenient and inexpensive, they have uncertain validity. We sought to assess the accuracy of longitudinally-collected automated survey responses compared to medical records. Using data collected from a well-characterized, prospective birth cohort over the first year of life, we examined concordance between guardians' reports of their infants' health care visits ascertained by weekly automated survey (IVR or email) and those identified by medical chart review. Among 180 survey-visit pairs, concordance was 51%, with no change as number of visits per baby increased. Accuracy of recall was higher by email compared to IVR (61 vs. 43%; adjusted OR = 2.5 95% CI: 1.3-4.8), did not vary by health care encounter type (hospitalization: 50%, ER: 64%, urgent care: 44%, primary care: 52%; p = 0.75), but was higher for fever (77%, adjusted OR = 5.1 95%CI: 1.5-17.7) and respiratory illness (58%, adjusted OR = 2.9 95%CI: 1.5-5.8) than for other diagnoses. For the 75 mothers in these encounters, 69% recalled at least one visit; among 41 mothers with two or more visits, 85% recalled at least one visit. Predictors of accurate reporting by mothers after adjusting for illness in the baby included increased age and increased years of education (age per year, β = 0.05, p = 0.03; education per year, β = 0.08, p = 0.04). Additional strategies beyond use of automated surveys are needed to ascertain accurate health care utilization in longitudinal cohort studies, particularly in healthy populations with little motivation for accurate reporting.

The impact analysis of a multiplex PCR respiratory panel for hospitalized pediatric respiratory infections in Japan

Background

Rapid molecular diagnosis of infections has contributed to timely treatments and antimicrobial stewardship. However, the benefit and cost-effectiveness vary in each country or community because they have different standard practices and health care systems. In Japan, rapid antigen tests (RATs) have been frequently used for pediatric respiratory infections. We investigated the impact and cost-effectiveness of a multiplex PCR (mPCR) respiratory panel for pediatric respiratory infections in a Japanese community hospital.

Methods

We replaced RATs with an mPCR respiratory panel (FilmArray®) for admitted pediatric respiratory infections on March 26, 2018. We compared the days of antimicrobial therapy (DOT) and length of stay (LOS) during the mPCR period (March 2018 to April 2019) with those of the RAT period (March 2012 to March 2018).

Results

During the RAT and mPCR periods, 1132 and 149 patients were analyzed. The DOT/case was 12.82 vs 8.56 (p < 0.001), and the LOS was 8.18 vs 6.83 days (p = 0.032) in the RAT and mPCR groups, respectively. The total costs during admissions were ∖258,824 ($2331.7) and ∖243,841 ($2196.8)/case, respectively. Pathogen detection rates were 30.2% vs 87.2% (p < 0.001).

Conclusion

Compared to conventional RATs, the mPCR test contributed to a reduction in the DOT and LOS in a Japanese community hospital for admission-requiring pediatric respiratory infections. However, a proper stewardship program is essential to further reduce the unnecessary usage of antimicrobials.

Early nasal microbiota and acute respiratory infections during the first years of life

BACKGROUND

Emerging evidence shows that airway microbiota may modulate local immune responses, thereby contributing to the susceptibility and severity of acute respiratory infections (ARIs). However, there are little data on the longitudinal relationships between airway microbiota and susceptibility to ARIs in children.

OBJECTIVE

We aimed to investigate the association of early nasal microbiota and the subsequent risk of ARIs during the first years of life.

METHODS

In this prospective population-based birth-cohort study in Finland, we followed 839 healthy infants for ARIs from birth to age 24 months. Nasal microbiota was tested using 16S rRNA gene sequencing at age 2 months. We applied an unsupervised clustering approach to identify early nasal microbiota profiles, and examined the association of profiles with the rate of ARIs during age 2-24 months.

RESULTS

We identified five nasal microbiota profiles dominated by Moraxella, Streptococcus, Dolosigranulum, Staphylococcus and Corynebacteriaceae, respectively. Incidence rate of ARIs was highest in children with an early Moraxella-dominant profile and lowest in those with a Corynebacteriaceae-dominant profile (738 vs 552/100 children years; unadjusted incidence rate ratio (IRR), 1.34; 95% CI 1.16 to 1.54; p < 0.001). After adjusting for nine potential confounders, the Moraxella-dominant profile-ARI association persisted (adjusted IRR (aIRR), 1.19; 95% CI 1.04 to 1.37; p = 0.01). Similarly, the incidence rate of lower respiratory tract infections (a subset of all ARIs) was significantly higher in children with an early Moraxella-dominant profile (aIRR, 2.79; 95% CI 1.04 to 8.09; p = 0.04).

CONCLUSION

Moraxella-dominant nasal microbiota profile in early infancy was associated with an increased rate of ARIs during the first 2 years of life.

Analysis of Invasive Nontypeable Haemophilus influenzae Isolates Reveals Selection for the Expression State of Particular Phase-Variable Lipooligosaccharide Biosynthetic Genes

Nontypeable Haemophilus influenzae (NTHi) is a major human pathogen, responsible for several acute and chronic infections of the respiratory tract. The incidence of invasive infections caused by NTHi is increasing worldwide. NTHi is able to colonize the nasopharynx asymptomatically, and the exact change(s) responsible for transition from benign carriage to overt disease is not understood. We have previously reported that phase variation (the rapid and reversible ON-OFF switching of gene expression) of particular lipooligosaccharide (LOS) glycosyltransferases occurs during transition from colonizing the nasopharynx to invading the middle ear. Variation in the structure of the LOS is dependent on the ON/OFF expression status of each of the glycosyltransferases responsible for LOS biosynthesis. In this study, we surveyed a collection of invasive NTHi isolates for ON/OFF expression status of seven phase-variable LOS glycosyltransferases. We report that the expression state of the LOS biosynthetic genes oafA ON and lic2A OFF shows a correlation with invasive NTHi isolates. We hypothesize that these gene expression changes contribute to the invasive potential of NTHi. OafA expression, which is responsible for the addition of an O-acetyl group onto the LOS, has been shown to impart a phenotype of increased serum resistance and may serve as a marker for invasive NTHi.

Timing of First Respiratory Virus Detections in Infants: A Community-Based Birth Cohort Study

Background

Determining timing of first virus detection episodes (fVDEs) for different respiratory viruses in infants identifies risk periods and informs preventive interventions, including vaccination. We describe the ages and nature of fVDEs in an infant birth cohort and explore factors associated with increased odds of symptomatic fVDEs.

Methods

The Observational Research in Childhood Infectious Diseases (ORChID) study is a community-based birth cohort describing acute respiratory infections in infants until their second birthday. Parents recorded daily symptoms and collected nose swabs weekly, which were batch-tested using polymerase chain reaction assays for 17 respiratory viruses.

Results

One hundred fifty-eight infants participated in ORChID. The median age for fVDEs was 2.9 months for human rhinovirus (HRV) but was ≥13.9 months for other respiratory viruses. Overall, 52% of HRV fVDEs were symptomatic, compared with 57%–83% of other fVDEs. Respiratory syncytial virus and human metapneumovirus fVDEs were more severe than HRV fVDEs. Older age and the winter season were associated with symptomatic episodes.

Conclusions

Infants do not always experience respiratory symptoms with their fVDE. Predominance of early HRV detections highlights the need for timing any intervention early in life. fVDEs from other respiratory viruses most commonly occur when maternal vaccines may no longer provide protection.

Nasal swab bacteriology by PCR during the first 24-months of life: A prospective birth cohort study

BACKGROUND

Most respiratory bacterial carriage studies in children are based on cross-sectional samples or longitudinal studies with infrequent sampling points. The prospective Observational Research in Childhood Infectious Diseases birth cohort study intensively evaluated the community-based epidemiology of respiratory viruses and bacteria during the first 2-years of life. Here we report the bacteriologic findings.

METHODS

Pregnant women in Brisbane, Australia were recruited between September 2010 and October 2012, and their healthy newborn children were followed for the first 2-years of life. Parents kept a daily symptom diary for the study child, collected a weekly anterior nose swab and completed an illness burden diary when their child met pre-defined illness criteria. Specimens were tested for respiratory bacteria by real-time polymerase chain reaction (PCR) assays and those containing human genomic DNA, deemed as high-quality, were analyzed.

RESULTS

Altogether 8100 high-quality nasal swab specimens from 158 enrolled children were analyzed. Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae were detected in 42.4%, 38.9%, and 14.8% of these samples, respectively. Concomitant detection of bacteria was common. In contrast, Bordetella pertussis, B. parapertussis, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Simkania negevensis were rarely identified. The prevalence of the three major bacteria was higher with increasing age and in the winter and spring months. Siblings and childcare attendance were the other risk factors identified.

CONCLUSIONS

We confirmed the feasibility of frequent nasal swabbing by parents for studying bacterial colonization. PCR detected the major respiratory tract bacteria with expected high frequencies, but atypical bacteria were found rarely in this cohort.

Geographical disparities in emergency department presentations for acute respiratory infections and risk factors for presenting: a population-based cohort study of Western Australian children

INTRODUCTION

Studies examining acute respiratory infections (ARIs) in emergency department (EDs), particularly in rural and remote areas, are rare. This study aimed to examine the burden of ARIs among Aboriginal and non-Aboriginal children presenting to Western Australian (WA) EDs from 2002 to 2012.

METHOD

Using a retrospective population-based cohort study linking ED records to birth and perinatal records, we examined presentation rates for metropolitan, rural and remote Aboriginal and non-Aboriginal children from 469 589 births. We used ED diagnosis information to categorise presentations into ARI groups and calculated age-specific rates. Negative binomial regression was used to investigate association between risk factors and frequency of ARI presentation.

RESULTS

Overall, 26% of presentations were for ARIs. For Aboriginal children, the highest rates were for those aged <12 months in the Great Southern (1233 per 1000 child-years) and Pilbara regions (1088 per 1000 child-years). Rates for non-Aboriginal children were highest in children <12 months in the Southwest and Kimberley (400 and 375 per 1000 child-years, respectively). Presentation rates for ARI in children from rural and remote WA significantly increased over time in all age groups <5 years. Risk factors for children presenting to ED with ARI were: male, prematurity, caesarean delivery and residence in the Kimberley region and lower socio-economic areas.

CONCLUSION

One in four ED presentations in WA children are for ARIs, representing a significant out-of-hospital burden with some evidence of geographical disparity. Planned linkages with hospital discharge and laboratory detection data will aid in assessing the sensitivity and specificity of ARI diagnoses in ED.

The Respiratory Specimen Collection Trial (ReSpeCT): A Randomized Controlled Trial to Compare Quality and Timeliness of Respiratory Sample Collection in the Home by Parents and Healthcare Workers From Children Aged <2 Years

BACKGROUND

Most acute respiratory infection (ARI) research focuses on severe disease and overlooks the burden of community-managed illness. For community-based studies, home-based specimen collection by parents could be a resource-saving alternative to collection by healthcare workers (HCWs). In this study, we compared parent and HCW groups for their likelihood to collect specimens and the timeliness and quality of such collection.

METHODS

In this unblinded randomized controlled trial, parents from Brisbane, Australia, were taught to identify new ARI episodes in their children aged <2 years. When their child had a new ARI, parents either collected a nasal swab from the child (P group) or contacted an HCW who visited to obtain a nasopharyngeal swab (HCW group). We compared the likelihood and timeliness of specimen collection and respiratory pathogen detection. A nested diagnostic study compared paired specimen collections from children in the HCW group.

RESULTS

Included were 76 incident ARI episodes from 31 children and 102 episodes from 33 children in the P and HCW groups, respectively. The proportions of ARIs for which a specimen was collected were similar (P group, 69.7%; HCW group, 72.5%; P = .77), and pathogens were detected in 93.8% and 77.5% of the specimens, respectively (P = .03). The period between ARI onset and specimen collection was shorter in the P group than in the HCW group (mean difference, 1.9 days [95% confidence interval, 0.7-3.0 days]; P < .001). For the 69 paired specimens, viral loads were lower in the parent-collected swabs (mean cycle threshold difference, 4.5 [95% confidence interval, 3.1-5.9]; P < .001).

CONCLUSIONS

Parents and HCWs obtained samples in similar proportions of ARI episodes, but the parents collected the samples fewer days after ARI onset and with a resulting higher likelihood of pathogen identification. This method can be used in population-based epidemiological studies of ARI as a resource-saving alternative.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT00966069.

Lactobacillus rhamnosus GG can protect malnourished children

Malnutrition affects virtually all organ systems, and malnourished children are more prone to infections. These children have dysbiosis, but probiotics can restore the disrupted gut microbiome. We investigated the protective effects of Lactobacillus rhamnosus GG in malnourished children in terms of incidence of infection, and anthropometric and metabolic parameters. 50 intervention and 50 control patients, aged 6 months to 5 years, with body weight and height below -2 SD, were randomly and prospectively recruited. The controls received a calorie and protein-appropriate diet for 3 months, while the study group additionally received approximately 10⁹ L. rhamnosus GG for 3 months. Infection episodes and nutritional status were compared between the groups. 38 intervention, 33 control patients completed the study and the two groups were similar at baseline. The study group had fewer upper respiratory tract infections and gastroenteritis episodes at each month and at the end of the study. Children in the study group experienced fewer total upper respiratory infections and urinary tract infections. Hospitalisation was more frequent in the control group during the third month and at the end of the study. Total infection numbers were higher in the control group at each month and at the end of the study (P<0.001 for each). Increments in body mass index (BMI) and BMI Z-scores were more pronounced in the study group (P=0.008 and P=0.02, respectively). Daily prophylactic use of L. rhamnosus GG at 10⁹ bacteria in malnourished children prevents most infections and improves nutritional status when used together with appropriate diet.

The Cost of Acute Respiratory Infections With Cough Among Urban Aboriginal and Torres Strait Islander Children

Introduction: Acute respiratory infections with cough (ARIwC) contribute considerably to childhood morbidity, yet few studies have examined the cost of these illnesses among Australian children. Moreover, of the few studies that have, none are inclusive of Aboriginal and/or Torres Strait Islander children, despite this population experiencing a greater burden of respiratory illnesses. This study aimed to determine the costs of ARIwC among urban Aboriginal and/or Torres Strait Islander children from the perspective of caretakers, the public healthcare system, and employers. Methods: This cost of illness study used data collected from Aboriginal and/or Torres Strait Islander children aged <5 years enrolled in a 12 month prospective cohort study conducted through an urban primary healthcare clinic in Queensland, Australia. Illness-related resource use was collected for each episode of ARIwC reported, and costed at market rates. Linear regression was used to (a) examine cost per episode by season of illness onset and cough duration and (b) examine cost per month of observation by baseline child and family characteristics. Results: During the study period, a total of 264 episodes of ARIwC were reported among 138 children. The total mean cost was estimated to be $AU252 per non-hospitalized episode (95%CI 169-334). Caretakers, the public healthcare system and employers incurred 44, 39, and 17% of costs per episode, respectively. After accounting for months of completed follow-ups, the total mean cost per child per year was estimated to be $991 (95%CI 514-1468). Winter episodes and episodes resulting in chronic cough were associated with significantly higher costs per episode. A prior history of wheezing, connections to traditional lands and parent/guardian belief that antibiotics should be given until symptoms resolved were associated with significantly higher cost per child month of observation. Conclusion: The cost of ARIwC in this predominantly disadvantaged population is substantial, particularly for caretakers and this needs to be considered in both clinical management and public health initiatives. The importance of cultural factors on health and burden of illness should not be overlooked. Further research into the prevention of chronic cough may play an important role in reducing the economic burden of pediatric respiratory infections.

Viruses causing lower respiratory symptoms in young children: findings from the ORChID birth cohort

INTRODUCTION

Viral acute respiratory infections (ARIs) cause substantial child morbidity. Sensitive molecular-based assays aid virus detection, but the clinical significance of positive tests remains uncertain as some viruses may be found in both acutely ill and healthy children. We describe disease-pathogen associations of respiratory viruses and quantify virus-specific attributable risk of ARIs in healthy children during the first 2 years of life.

METHODS

One hundred fifty-eight term newborn babies in Brisbane, Australia, were recruited progressively into a longitudinal, community-based, birth cohort study conducted between September 2010 and October 2014. A daily tick-box diary captured predefined respiratory symptoms from birth until their second birthday. Weekly parent-collected nasal swabs were batch-tested for 17 respiratory viruses by PCR assays, allowing calculation of virus-specific attributable fractions in the exposed (AFE) to determine the proportion of virus-positive children whose ARI symptoms could be attributed to that particular virus.

RESULTS

Of 8100 nasal swabs analysed, 2646 (32.7%) were virus-positive (275 virus codetections, 3.4%), with human rhinoviruses accounting for 2058/2646 (77.8%) positive swabs. Viruses were detected in 1154/1530 (75.4%) ARI episodes and in 984/4308 (22.8%) swabs from asymptomatic periods. Respiratory syncytial virus (AFE: 68% (95% CI 45% to 82%)) and human metapneumovirus (AFE: 69% (95% CI 43% to 83%)) were strongly associated with higher risk of lower respiratory symptoms.

DISCUSSION

The strong association of respiratory syncytial virus and human metapneumovirus with ARIs and lower respiratory symptoms in young children managed within the community indicates successful development of vaccines against these two viruses should provide substantial health benefits.

Detecting Acute Otitis Media Symptom Episodes Using a Mobile App: Cohort Study

BACKGROUND

Population cohort studies are useful to study infectious diseases episodes not attended by health care services, but conventional paper diaries and questionnaires to capture cases are prone to noncompliance and recall bias. Use of smart technology in this setting may improve case finding.

OBJECTIVE

The objective of our study was to validate an interactive mobile app for monitoring occurrence of acute infectious diseases episodes in individuals, independent of health care seeking, using acute otitis media (AOM) symptom episodes in infants as a case study. We were interested in determining participant compliance and app performance in detecting and ascertaining (parent-reported) AOM symptom episodes with this novel tool compared with traditional methods used for monitoring study participants.

METHODS

We tested the InfectieApp research app to detect AOM symptom episodes. In 2013, we followed 155 children aged 0 to 3 years for 4 months. Parents recorded the presence of AOM symptoms in a paper diary for 4 consecutive months and completed additional disease questionnaires when AOM symptoms were present. In 2015 in a similar cohort of 69 children, parents used an AOM diary and questionnaire app instead.

RESULTS

During conventional and app-based recording, 93.13% (17,244/18,516) and 94.56% (7438/7866) of symptom diaries were returned, respectively, and at least one symptom was recorded for 32.50% (n=5606) and 43.99% (n=3272) of diary days (P<.01). The incidence of AOM symptom episodes was 605 and 835 per 1000 child-years, respectively. Disease questionnaires were completed for 59% (17/29) of episodes when participants were using conventional recording, compared with 100% (18/18) for app-based recording.

CONCLUSIONS

The use of the study's smart diary app improved AOM case finding and disease questionnaire completeness. For common infectious diseases that often remain undetected by health care services, use of this technology can substantially improve the accurateness of disease burden estimates.

Defining 'healthy' in preschool-aged children for forced oscillation technique reference equations

BACKGROUND AND OBJECTIVE

Selecting 'healthy' preschool-aged children for reference ranges may not be straightforward. Relaxing inclusion criteria for normative data does not affect spirometry z-scores. We therefore investigated the effect of similarly relaxing inclusion criteria in preschoolers on reference ranges for respiratory impedance (Zrs) using a modified forced oscillation technique (FOT).

METHODS

The International Study of Asthma and Allergies in Childhood questionnaire classified 585 children into a healthy and five mutually exclusive groups. Zrs was measured between 4 and 26 Hz and resistance (R) and compliance (C) obtained by model fitting. Prediction models were determined using mixed effect models and z-scores compared between healthy children and the five groups.

RESULTS

Zrs data were obtained for 494 participants (4.30 ± 0.7 years) on 587 occasions. Comparison of the Zrs z-scores between the healthy children and the health groups found significant differences in children with asthma, current wheeze and respiratory symptoms, but not in children born preterm or with early-life wheeze. Adding these two groups to the healthy dataset had no significant effect on the distribution of z-scores and increased the size of the dataset by 22.3%.

CONCLUSION

Our data suggest that preschool-aged children born preterm or with early-life wheeze can be included in FOT reference equations, while those with asthma, current wheeze and respiratory symptoms within 4 weeks of testing should be excluded. This more inclusive approach results in more robust FOT reference ranges.

Effect of Disease Definition on Perceived Burden of Acute Respiratory Infections in Children: A Prospective Cohort Study Based on Symptom Diaries

BACKGROUND

Acute respiratory infections (ARIs) are among the most frequent childhood diseases in Western countries. Assessment of ARI episodes for research purposes is usually based on parent-administered retrospective questionnaires or prospective symptom diaries. The aim of our analysis was to compare the effect of ARI definitions on the corresponding disease burden in a prospective cohort study using symptom diaries.

METHODS

A literature search was performed to identify definitions of ARI used in research studies. The definitions were applied to a symptom diary dataset from a cohort study of 1-3-year-old children conducted in the winter season 2013/2014. We compared the total number of ARI episodes, the total number of days with ARI and the median and mean duration of ARI episodes resulting from the use of the different definitions.

RESULTS

Six ARI definitions were identified in the literature. Depending on ARI definition, the total number of ARI episodes and the total number of days with ARI in our dataset varied by a factor of 1.69 and 1.53, respectively, between the lowest and the highest. The median duration of the episodes ranged from 7 to 10 days.

DISCUSSION

Different definitions led to considerable differences in the number and duration of ARI episodes, making direct comparisons of studies with different methods questionable. We propose the use of a standardized ARI definition in upcoming cohort studies working with diary data. This process could be conducted using a Delphi survey with experts in this study field.

Incidence and comparison of retrospective and prospective data on respiratory and gastrointestinal infections in German households

Background

Acute respiratory infections (ARI) and acute gastrointestinal infections (AGI) are the most common childhood infections, and corresponding data can either be collected prospectively or retrospectively. The aim of this study was to estimate the incidence of respiratory and gastrointestinal episodes in German households with children attending day care and to compare results of prospective and retrospective data collection.

Methods

We conducted a 4 months prospective cohort study in the winter period 2014/2015 and recruited parents of children aged 0–6 years in 75 day care centers in Braunschweig, Lower Saxony, Germany. For all household members, we collected information on episodes of ARI and AGI. We applied prospective data collection in one study arm and retrospective data collection with a reporting period of 2 months in the other. Poisson regression was used to model monthly incidence rates for both study arms.

Results

In total, 100 households (including 404 persons) participated in the retrospective group and 77 households (282 persons) in the prospective group. Incidence estimates for ARI (retrospective group: 0.52 per person month, prospective group: 0.47) were higher than for AGI (retrospective group: 0.14, prospective group: 0.13). The adjusted incidence estimates were similar in both study arms for ARI (incidence rate ratio for retrospective versus prospective data collection: 1.11 [confidence interval (CI) 95% 0.99; 1.24], p = 0.42) as well as for AGI (1.10 [CI 95% 0.89; 1.37], p = 0.27).

Conclusion

If there is no need to collect biomaterials or data on severity of the diseases, incidence of infections in the household setting over a short time period (2 months) can be assessed retrospectively.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2434-5) contains supplementary material, which is available to authorized users.

Acute Otitis Media During Infancy: Parent-reported Incidence and Modifiable Risk Factors

BACKGROUND

Age at exposure to acute otitis media (AOM) risk factors such as day care attendance, lack of breastfeeding and tobacco smoke is little studied but important for targeting AOM prevention strategies. Moreover, studies are typically restricted to clinically diagnosed AOM, while a significant subset can occur outside the health care system, depending on the country setting. This study aims to determine risk factor exposure and effect of its timing within the first year of life on parent-reported AOM symptom episodes.

METHODS

In the WHeezing and Illnesses STudy LEidsche Rijn birth-cohort study, 1056 children were prospectively followed during their first year of life. Group day care attendance, breastfeeding and tobacco smoke exposure were recorded monthly and parent-reported AOM symptoms daily. Generalized estimating equations were used to estimate the association between the time-varying risk factors and AOM symptom episodes, while correcting for confounding by indication.

RESULTS

The first-year incidence rate of parent-reported AOM was 569/1000 child-years [95% confidence interval (CI): 523-618]. Children who attended day care had higher odds of developing AOM symptom episodes compared with those not attending (odds ratio: 5.0; 95% CI: 2.6-9.6). Tobacco smoke exposure and (a history of) breastfeeding were not associated with AOM. Test for interaction revealed that the effect of day care increased with each month younger in age.

CONCLUSIONS

First-year day care attendance is a major risk factor for AOM symptom episodes among infants in the community. This adjusted effect estimate is higher than previously reported and is age-dependent. AOM prevention strategies in day care facilities should therefore focus in particular on the youngest age groups.

The Incidence and Short-term Outcomes of Acute Respiratory Illness with Cough in Children from a Socioeconomically Disadvantaged Urban Community in Australia: A Community-Based Prospective Cohort Study

BACKGROUND

Acute respiratory illnesses with cough (ARIwC) are predominant causes of morbidity in Australian Indigenous children; however, data on disease burden in urban communities are scarce. This study aimed to determine the incidence of ARIwC, the predictors of recurrent (≥4 episodes) ARIwC, and development of chronic cough following an ARIwC in urban, predominantly Indigenous, children aged <5 years from northern Brisbane, Australia.

METHODS

Prospective cohort study of children aged <5 years registered with a primary healthcare center. ARIwC episodes and outcomes were collected for 12 months. Recurrent ARIwC was defined as ≥4 episodes in 12 months. Chronic cough was defined as cough lasting >4 weeks. Children who developed chronic cough were reviewed by a pediatric pulmonologist. Incidence densities per child-month of observation were calculated and predictors of recurrent ARIwC and chronic cough were evaluated in logistic regression models.

RESULTS

Between February 2013 and November 2015, 200 children were enrolled; median age of 18.1 months, range (0.7-59.7 months) and 90% identified as Indigenous. A total of 1,722 child-months of observation were analyzed (mean/child = 8.58, 95% CI 8.18-9.0). The incidence of ARIwC was 24.8/100 child-months at risk (95% CI 22.3-27.5). Twenty-one children (10.5%) experienced recurrent ARIwC. Chronic cough was identified in 70/272 (25.7%) episodes of ARIwC. Predictors of recurrent ARIwC were presence of eczema, mold in the house, parent/carer employment status, and having an Aboriginal and Torres Strait Islander mother/non-Aboriginal and Torres Strait Islander father (compared to both parents being Aboriginal and Torres Strait Islander). Predictors of chronic cough included being aged <12 months, eczema, childcare attendance, previous history of cough of >4 weeks duration, having an Aboriginal and Torres Strait Islander mother/non-Aboriginal and Torres Strait Islander father (compared to both parents being Aboriginal and Torres Strait Islander), and a low income. Of those with chronic cough reviewed by a pediatric pulmonologist, a significant underlying disorder was found in 14 children (obstructive sleep apnea = 1, bronchiectasis = 2, pneumonia = 2, asthma = 3, tracheomalacia = 6).

DISCUSSION

This community of predominantly Aboriginal and Torres Strait Islander and socially disadvantaged children bear a considerable burden of ARIwC. One in 10 children will experience more than three episodes over a 12-month period and 1 in five children will develop chronic cough post ARIwC, some with a serious underlying disorder. Further larger studies that include a broader population base are needed.