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

Understanding the childhood origins of asthma and chronic obstructive pulmonary disease: Insights from birth cohorts and studies across the life-span

Birth cohorts have identified modifiable risk factors for asthma and respiratory health in children and adults, demonstrating the important role and pathways through which early-life events influence not only child outcomes but also adult health, disease, and mortality. This focused literature update from 2021 to 2024 summarizes birth cohort studies across the life-span that contribute to our understanding of risk factors for and the childhood origins of asthma and chronic obstructive pulmonary disease that may inform prevention efforts. We conclude that there are critical periods of developmental plasticity and susceptibility during which early-life events and exposures likely have the greatest impact on the development of asthma and chronic obstructive lung disease phenotypes, and that there are important prenatal and early childhood exposures, which, if modified, might be candidates for improving respiratory health across the life-span. Birth cohorts have been and will continue to be critical to advancing our understanding of lung health and disease across the life-span, including asthma and chronic obstructive pulmonary disease. As child mortality declines and the human population ages, data from birth cohort studies are needed to inform strategies for optimizing healthy longevity, including the investment in understanding the lifelong consequences of adverse prenatal and early childhood exposures.

Caesarean section and risk of infection in offspring: systematic review and meta-analysis of observational studies

Objective

To compare the risk of hospital admissions with infections and infections not in hospital in children born by caesarean section with children born by vaginal birth.

Data sources

Medline, Embase, and PubMed were searched with no restriction on start date up to 12 February 2024.

Study selection

Observational studies were included that reported the association between caesarean section and vaginal birth in relation to the risk of infections (both those that lead to hospital admission and those that do not) up to 18 years of age. Studies were excluded if they were not representative of a general population or if they focused on congenital, neonatal, or vertically acquired infections. No restrictions were made for language, publication date, or setting.

Review methods

Findings for hospital admissions with infection were synthesised by meta-analyses of specific infection outcomes and type of caesarean birth (emergency v elective) and findings for other infections (ie, infection episodes reported by parents and primary care visits) by direction of effect. Risk of bias was assessed using the ROBINS-E tool and the overall certainty of evidence through the GRADE framework.

Results

31 eligible studies of over 10 million children were included. Findings were from population-based birth cohorts and registry data linkage studies in high income countries. Cohort sizes ranged from 288 to 7.2 million and follow up age was from one to 18 years. Outcomes included overall and specific clinical categories of infection. From studies of overall admission to hospital with infection, the proportion of children admitted ranged between 9-29% across exposure groups. In random-effects meta-analyses combining hazard ratios, children delivered by caesarean section had an increased rate of hospital admission with infections overall and in three common clinical infection categories: (1) overall admissions to hospital with infection (emergency caesarean section: n=6 study populations, hazard ratio 1.10 (95% confidence interval 1.06 to 1.14), τ 2=0.0009, I2=96%; elective caesarean section: n=7, 1.12 (1.09 to 1.15), τ 2=0.0006, I2=88%); (2) admission to hospital for upper respiratory infections (emergency caesarean section: n=7, 1.11 (1.09 to 1.13), τ 2=0.0003, I2=73%; elective caesarean section: n=7, 1.16 (1.12 to 1.20), τ 2=0.0012, I2=89%); (3) admission to hospital for lower respiratory infections (emergency caesarean section: n=8, 1.09 (1.06 to 1.12), τ 2=0.0010, I2=88%; elective caesarean section: n=8, 1.13 (1.10 to 1.16), τ 2=0.0009, I2=84%); (4) admission to hospital for gastrointestinal infections (emergency caesarean section: n=7, 1.19 (1.13 to 1.26), τ 2=0.0025, I2=86%; elective caesarean section: n=7, 1.20 (1.15 to 1.25), τ 2=0.0009, I2=67%). Eight of 11 studies of other infections suggested an increased risk of their primary infection outcome in those born by caesarean section. Risk of bias concerns primarily related to confounding.

Conclusions

Findings from high income countries showed a consistent association between caesarean section birth and greater risk of infections in children across various settings. Limitations of existing studies include the potential for unmeasured confounding, specifically confounding by indication, and a scarcity of studies from low and middle income countries.

Review registration

PROSPERO (CRD42022369252).

Real time monitoring of respiratory viral infections in cohort studies using a smartphone app

Cohort studies investigating respiratory disease pathogenesis aim to pair mechanistic investigations with longitudinal virus detection but are limited by the burden of methods tracking illness over time. In this study, we explored the utility of a purpose-built AERIAL TempTracker smartphone app to assess real-time data collection and adherence monitoring and overall burden to participants, while identifying symptomatic respiratory illnesses in two birth cohort studies. We observed strong adherence with daily app usage over the six-month study period, with positive feedback from participant families. A total of 648 symptomatic respiratory illness events were identified with significant variability between individuals in the frequency, duration, and virus detected. Collectively, our data show that a smartphone app provides a reliable method to capture the longitudinal virus data in cohort studies which facilitates the understanding of early life infections in chronic respiratory disease development.

Serum Levels of Selected Cytokines and Chemokines and IgG4 in Children With Recurrent Respiratory Tract Infections

Background: Respiratory tract infections are a common health problem. Cytokines/chemokines play a critical role in the regulation of the immune system. Their defective production may predispose to recurrent respiratory tract infections (RRIs), and an excessive immune response may lead to chronic inflammation and cause damage to the respiratory tract. Another biomarker of respiratory infections may be immunoglobulin-IgG4. Its meaning has still been little explored. We wanted to assess the suitability of the levels of biomarkers tested: interleukin (IL)-17A, IL-18, IL-23, normal T cells expressed and secreted (RANTES), and induced protein (IP)-10, as well as immunoglobilun G4 (IgG4) to predict recurrent infections. Methods: The study group (SG) included a total of 130 children (68 girls, 62 boys) between 3 and 17 years of age with RRI. The control group (CG) included 86 healthy children with no symptoms of inflammatory or allergic diseases (44 girls and 42 boys) of the same age. Blood samples were collected in fasting state and then serum samples were frozen and stored until biomarker assay. Results: Serum RANTES, IL-18, IL-23, and IgG4 concentration were higher in all children with recurrent infections vs. those in the CG (p  < 0001). Serum levels of IL-17A and IP-10 were also significantly higher in the SG than in the CG, but only in the youngest children. Among the six serum markers, RANTES demonstrated the highest area under the receiver operating characteristic curve (area under curve) value (0.998, 95% confidence interval [CI]: 0.98-1.0, p < 0.001) for the diagnosis of RRIs, followed by IL-23 (0.99, 95% CI 0.966-0,999, p < 0.001) and IL-18 (0.957, 95% CI 0.921-0.980, p < 0.001). Conclusions: RANTES, IL-23, and IL-18 could be strong predictors of respiratory infections recurrence in children.

Randomised multicentre effectiveness trial of rapid syndromic testing by panel assay in children presenting to European emergency departments with acute respiratory infections-trial protocol for the ADEQUATE Paediatric trial

INTRODUCTION

Syndromic panel assays, that is, using one test to simultaneously target multiple pathogens with overlapping signs and symptoms, have been integrated into routine paediatric care over the past decade, mainly for more severely ill and hospitalised patients. Their wider availability and short turnaround times open the possibility to apply them to non-hospitalised patients as well. In this context, it is important to trial how clinicians make use of pathogen detection data and if their early availability influences management decisions, particularly antibiotic use and hospitalisation.

METHODS AND ANALYSIS

Advanced Diagnostics for Enhanced QUality of Antibiotic prescription in respiratory Tract infections in Emergency rooms is an individually randomised, controlled, open-label effectiveness trial comparing the impact of a respiratory pathogen panel assay (BIOFIRE Respiratory Panel 2.1plus) used as a rapid syndromic test on nasopharyngeal swabs in addition to the standard of care versus standard of care alone. The trial will 1:1 randomise 520 participants under the age of 18 at 7 paediatric emergency departments in 5 European countries. Inclusion criteria for the trial consist of two sets, with the first describing respiratory tract infections in paediatric patients and the second describing the situation of potential management uncertainty in which test results may immediately affect management decisions. Enrolment started in July 2021 and is expected to be completed in early 2024. We will perform a two-sample t-test assuming a pooled variance estimate to compare the log-transformed mean time on antibiotic treatment (in hours) and number of days alive out of the hospital within 14 days after study enrolment between the control and intervention arms.

ETHICS AND DISSEMINATION

The trial protocol and materials were approved by research ethics committees in all participating countries. The respiratory pathogen panel assay is CE marked (assessed to meet European regulations) and FDA (United States Food and Drug Administration) cleared for diagnostic use. Participants and caregivers provide informed consent prior to study procedures commencing. The trial results will be published in peer-reviewed journals and at national and international conferences. Key messages will also be disseminated via press and social media where appropriate.

TRIAL REGISTRATION NUMBER

NCT04781530.

The epidemic forest reveals the spatial pattern of the spread of acute respiratory infections in Jakarta, Indonesia

Acute respiratory infection (ARI) is a communicable disease of the respiratory tract that implies impaired breathing. The infection can expand from one to the neighboring areas at a region-scale level through a human mobility network. Specific to this study, we leverage a record of ARI incidences in four periods of outbreaks for 42 regions in Jakarta to study its spatio-temporal spread using the concept of the epidemic forest. This framework generates a forest-like graph representing an explicit spread of disease that takes the onset time, spatio-temporal distance, and case prevalence into account. To support this framework, we use logistic curves to infer the onset time of the outbreak for each region. The result shows that regions with earlier onset dates tend to have a higher burden of cases, leading to the idea that the culprits of the disease spread are those with a high load of cases. To justify this, we generate the epidemic forest for the four periods of ARI outbreaks and identify the implied dominant trees (that with the most children cases). We find that the primary infected city of the dominant tree has a relatively higher burden of cases than other trees. In addition, we can investigate the timely ( R t ) and spatial reproduction number ( R c ) by directly evaluating them from the inferred graphs. We find that R t for dominant trees are significantly higher than non-dominant trees across all periods, with regions in western Jakarta tend to have higher values of R c . Lastly, we provide simulated-implied graphs by suppressing 50% load of cases of the primary infected city in the dominant tree that results in a reduced R c , suggesting a potential target of intervention to depress the overall ARI spread.

The impact of non-pharmaceutical interventions on community non-SARS-CoV-2 respiratory infections in preschool children

BACKGROUND

Effects of non-pharmaceutical interventions during the pandemic were mainly studied for severe outcomes. Among children, most of the burden of respiratory infections is related to infections which are not medically attended. The perspective on infections in the community setting is necessary to understand the effects of the pandemic on non-pharmaceutical interventions.

METHODS

In the unique prospective LoewenKIDS cohort study, we compared the true monthly incidence of self-reported acute respiratory infections (ARI) in about 350 participants (aged 3-4 years old) between October 2019 to March 2020 (pre-pandemic period) and October 2020 to March 2021 (pandemic period). Parents reported children's symptoms using a diary. Parents were asked to take a nasal swab of their child during all respiratory symptoms. We analysed 718 swabs using Multiplex PCR for 25 common respiratory viruses and bacteria.

RESULTS

During the pre-pandemic period, on average 44.6% (95% CI: 39.5-49.8%) of children acquired at least one ARI per month compared to 19.9% (95% CI: 11.1-28.7%) during the pandemic period (Incidence Rate Ratio = 0.47; 95% CI: 0.41-0.54). The detection of influenza virus decreased absolute by 96%, respiratory syncytial virus by 65%, metapneumovirus by 95%, parainfluenza virus by 100%, human enterovirus by 96% and human bocavirus by 70% when comparing the pre-pandemic to the pandemic period. However, rhinoviruses were nearly unaffected by NPI. Co-detection (detection of more than one virus in a single symptomatic swab) was common in the pre-pandemic period (222 of 390 samples with viral detection; 56.9%) and substantially less common during the pandemic period (46 of 216 samples; 21.3%).

CONCLUSION

Non-pharmaceutical interventions strongly reduced the incidence of all respiratory infections in preschool children but did not affect rhinovirus.

Key risk factors of asthma-like symptoms are mediated through infection burden in early childhood

BACKGROUND

Risk factors of asthma-like symptoms in childhood may act through an increased infection burden because infections often trigger these symptoms.

OBJECTIVE

We sought to investigate whether the effect of established risk factors of asthma-like episodes in early childhood is mediated through burden and subtypes of common infections.

METHODS

The study included 662 children from the Copenhagen Prospective Studies on Asthma in Childhood 2010 mother-child cohort, in which infections were registered prospectively in daily diaries from age 0 to 3 years. The association between established risk factors of asthma-like episodes and infection burden was analyzed by quasi-Poisson regressions, and mediation analyses were performed for significant risk factors.

RESULTS

In the first 3 years of life, the children experienced a median of 16 (interquartile range, 12-23) infectious episodes. We found that the infection burden significantly (PACME < .05) mediated the association of maternal asthma (36.6% mediated), antibiotics during pregnancy (47.3%), siblings at birth (57.7%), an asthma exacerbation polygenic risk score (30.6%), and a bacterial airway immune score (80.2%) with number of asthma-like episodes, whereas the higher number of episodes from male sex, low birth weight, low gestational age, and maternal antibiotic use after birth was not mediated through an increased infection burden. Subtypes of infections driving the mediation were primarily colds, pneumonia, gastroenteritis, and fever, but not acute otitis media or acute tonsillitis.

CONCLUSIONS

Several risk factors of asthma-like symptoms in early childhood act through an increased infection burden in the first 3 years of life. Prevention of infectious episodes may therefore be beneficial to reduce the burden of asthma-like symptoms in early childhood.

Comparative Analysis of Outpatient Antibiotic Prescribing in Early Life: A Population-Based Study Across Birth Cohorts in Denmark and Germany

INTRODUCTION

Comparing antibiotic prescribing between countries can provide important insights into potential needs of improving antibiotic stewardship programs. We aimed to compare outpatient antibiotic prescribing in early life between children born in Denmark and Germany.

METHODS

Using the Danish nationwide healthcare registries and a German claims database (GePaRD, ~ 20% population coverage), we included children born between 2004 and 2016, and followed them regarding outpatient antibiotic prescriptions until end of enrollment or the end of 2018. We then determined the median time to first antibiotic prescription. Based on all prescriptions in the first 2 years of life, we calculated the rate of antibiotic treatment episodes and for the children's first prescriptions in this period, we determined established quality indicators. All analyses were stratified by birth year and country.

RESULTS

In the 2016 birth cohorts, the median time to first antibiotic prescription was ~ 21 months in Denmark and ~ 28 in Germany; the rate of antibiotic treatment episodes per 1000 person-years was 537 in Denmark and 433 in Germany; the percentage of prescribed antibiotics with higher concerns regarding side effects and/or resistance potential was 6.2% in Denmark and 44.2% in Germany. In the 2016 birth cohorts, the age at first antibiotic prescription was 50-59% higher compared to the 2004 birth cohorts; the rate of antibiotic treatment episodes was 43-44% lower.

CONCLUSIONS

Infants in Denmark received antibiotics markedly earlier and more frequently than in Germany, while quality indicators of antibiotic prescribing were more favorable in Denmark. Although both countries experienced positive changes towards more rational antibiotic prescribing in early life, our findings suggest potential for further improvement. This particularly applies to prescribing antibiotics with a lower potential for side effects and/or resistance in Germany.

Perinatal and Other Risk Factors for Common Infections in Infancy: A Prospective Cohort Study

OBJECTIVE

Limited data from prospective cohort studies in high-income countries are available on the perinatal risk factors for common infections in children. Our hypothesis was that perinatal factors may be risk factors for infectious episodes during the first year of life.

METHODS

In this prospective Health and Early Life Microbiota birth cohort study of full-term infants (n = 1052) born in 2016-2018, the number and duration of infection episodes were collected online at weekly to monthly intervals. In a multivariate regression model, the main exposures were perinatal factors such as mode of delivery and intrapartum antibiotics. Environmental factors were additional exposures. The outcomes were the number and duration of infectious episodes in the first year of life.

RESULTS

The mean number of infection episodes was 4.2 (2.9 SD). The mean duration of infection symptoms was 44 days (40 SD). Upper respiratory infections accounted for 83% of the episodes (3674/4455). Perinatal factors were not associated with the number nor the duration of infection episodes, but cesarean section was associated with an increased occurrence of urinary tract infections in infancy [adjusted odds ratio (aOR): 3.6; 95% confidence interval (CI): 1.13-11.1]. Of the additional exposures male sex (aOR: 1.1; 95% CI: 1.0-1.2) and the presence of siblings (aOR: 1.3; 95% CI: 1.2-1.4) were associated with the number of infection episodes.

CONCLUSIONS

This prospective cohort study showed that perinatal factors, mode of delivery and intrapartum antibiotics were not associated with the risk of common infections in infancy, but cesarean delivery was associated with a risk of urinary tract infections.

T cell repertoire breadth is associated with the number of acute respiratory infections in the LoewenKIDS birth cohort

We set out to gain insight into peripheral blood B and T cell repertoires from 120 infants of the LoewenKIDS birth cohort to investigate potential determinants of early life respiratory infections. Low antigen-dependent somatic hypermutation of B cell repertoires, as well as low T and B cell repertoire clonality, high diversity, and high richness especially in public T cell clonotypes reflected the immunological naivety at 12 months of age when high thymic and bone marrow output are associated with relatively few prior antigen encounters. Infants with inadequately low T cell repertoire diversity or high clonality showed higher numbers of acute respiratory infections over the first 4 years of life. No correlation of T or B cell repertoire metrics with other parameters such as sex, birth mode, older siblings, pets, the onset of daycare, or duration of breast feeding was noted. Together, this study supports that-regardless of T cell functionality-the breadth of the T cell repertoire is associated with the number of acute respiratory infections in the first 4 years of life. Moreover, this study provides a valuable resource of millions of T and B cell receptor sequences from infants with available metadata for researchers in the field.

Exclusive Breastfeeding and Childhood Morbidity: A Narrative Review

Globally, diarrheal diseases and acute respiratory infections are the leading causes of morbidity and mortality in children under 5 years old. The benefits of exclusive breastfeeding in reducing the risk of gastrointestinal and respiratory infections are well documented. Optimal breastfeeding may potentially save the lives of about 800,000 children in low-income settings. Despite the evidence, around 63% of infants from birth to 6 months are not exclusively breastfed worldwide. We searched the literature published between 2010 and 2022 in Medline, Embase, and Scopus on the association between exclusive breastfeeding and infectious diseases. We selected and reviewed 70 relevant studies. Our findings expand and confirm the positive association between exclusive breastfeeding and reduced risk of a number of gastrointestinal, respiratory, and other infections in 60 out of 70 studies observed in both low- and high-income settings. Several studies analyzing exclusive breastfeeding duration reported that a longer exclusive breastfeeding duration is protective against many infectious diseases. This review also reported a lack of standardized definition for measuring exclusive breastfeeding in many studies. Overall, the results highlight the benefits of exclusive breastfeeding in many studies and suggests reporting exclusive breastfeeding in future studies using a consistent definition to enable better monitoring of exclusive breastfeeding rates.