Shift in Clinical Epidemiology of Human Parainfluenza Virus Type 3 and Respiratory Syncytial Virus B Infections in Korean Children Before and During the COVID-19 Pandemic: A Multicenter Retrospective Study

The severity of respiratory syncytial virus infection in children during the SARS-CoV-2/COVID-19 pandemic: A nationwide study of 11,915 cases in Germany

PURPOSE

Respiratory syncytial virus (RSV) infection is a major cause of childhood hospitalization. The COVID-19 pandemic has disrupted the usual seasonal pattern of RSV, resulting in high activity during the off-season. This study aims to evaluate the effects of the pandemic on the severity of RSV infections.

METHODS

Data from 11,915 children hospitalized due to RSV infection between 2016 and 2022 were analyzed. The hospitalized patients were categorized into two groups, from January 2016 to February 2020 (PreCoV19 group) and from March 2020 to December 2022 (CoV19 group). The hospitalization duration, intensive care unit (ICU) admissions, length of stay at ICU, mechanical ventilation requirement and duration, Elixhauser comorbidity index scores, and in-hospital mortality were analyzed.

RESULTS

Children in the PreCoV19 group had a mean age of 0.4 ± 0.7, whereas those in the CoV19 group had a mean age of 0.6 ± 1.0 years. Children during the pandemic had significantly shorter hospital stays (4.3 ± 2.6 days) compared to children of the pre-pandemic period (4.9 ± 3.3 days). Although ICU admission rates did not change, the duration of ICU stays decreased in the CoV19 group. Moreover, the in-hospital mortality did not differ between the groups. A multivariable analysis showed that younger age, regardless of the pandemic period, was associated with prolonged hospital stays, higher ICU admission rates, and an increased requirement for mechanical ventilation.

CONCLUSION

Our findings highlight significant changes of the clinical characteristics of RSV infections during the pandemic, with implications for clinical management and public health strategies.

Hospitalizations for all-cause pediatric acute respiratory diseases in Alberta, Canada, before, during, and after the COVID-19 pandemic: a population-level retrospective cohort study from 2010 to 2024

Background

This population-level retrospective cohort study measured seasonal patterns of pediatric hospitalizations, pediatric intensive care unit (PICU) admissions, and average age of children diagnosed with acute respiratory diseases (ARD) during pre-pandemic, COVID-19 pandemic, and late/post-pandemic periods.

Methods

From September 2010 through August 2024, all hospitalizations for ARD among children <18 years old were identified from the provincial Discharge Abstract Database, in Alberta, Canada. Seasonal autoregressive integrated moving average (SARIMA) models were developed based on pre-pandemic trends and predicted expected weekly outcomes with 95% confidence intervals (95% CI) from March 2020 onward. Observed and expected outcomes with 95% CI were compared to measure impacts during peak seasons.

Findings

There were 52,839 ARD hospitalizations: 16,003 (30.29%) bronchiolitis, 7958 (15.06%) influenza-like illness, 14,366 (27.19%) pneumonia, 2989 (5.66%) croup, 10,266 (19.43%) asthma exacerbation, and 1257 (2.38%) COVID-19. Further, 4433 (8.39%) hospitalizations included a PICU admission. During the pre-pandemic period, hospitalizations for ARD had a biennial pattern, where the peak incidence was highest every other winter season. During the pandemic and late/post-pandemic periods, the average weekly incidence of hospitalization for ARD/100,000 children decreased 91.25% during winter 2020-2021 (1.03 observed vs. 11.81 [95% CI 7.30, 16.33] expected), increased 47.98% during winter 2022-2023 (18.06 observed vs. 12.20 [95% CI 7.06, 17.34] expected), and returned near pre-pandemic incidence during winter 2023-2024 (12.87 observed vs. 11.87 [95% CI 6.08, 17.67] expected) compared with incidence predicted by the SARIMA model. During winter 2022-2023 when hospitalizations surged, there was no significant change in the average weekly incidence of PICU admissions for ARD/100,000 children (2.07 observed vs. 1.26 [95% CI 0.26, 2.27] expected), nor percent PICU admissions (10.21% observed vs. 10.11% [95% CI 5.50, 14.73] expected), nor in average age (31.95 months observed vs. 34.20 months [95% CI 25.89, 42.52] expected).

Interpretation

Hospitalizations for pediatric ARD decreased dramatically during winter 2020-2021, surged during winter 2022-2023, and returned near pre-pandemic incidence during winter 2023-2024. There was no lasting change in PICU admissions nor average age. Ongoing surveillance will describe the evolving seasonal pattern of ARD during the post-pandemic period.

Funding

None.

RSV Prevention Strategies in Korean Children: A Review of Current Approaches and Emerging Options

Respiratory syncytial virus (RSV) poses a significant threat to infants and young children in Korea and globally. Current preventive measures, such as palivizumab, have limitations, necessitating the exploration of new strategies. Nirsevimab, a long-acting monoclonal antibody, has emerged as a promising option for protecting all infants from RSV. Clinical trials and real-world evidence support its effectiveness in reducing RSV-related hospitalizations. The economic burden of RSV infection in Korea underscores the need for cost-effective interventions. While several RSV vaccines are under development, none are currently available in Korea. Maternal immunization programs and vaccines for older infants offer potential avenues for expanding protection. This review highlights the evolving landscape of RSV prevention, with a shift towards nirsevimab and future vaccines. Further research is crucial to understand the long-term consequences of RSV infection and develop comprehensive prevention strategies tailored to the Korean population.

Changes in Respiratory Viruses' Activity in Children During the COVID-19 Pandemic: A Systematic Review

Background/Objectives: The impact of the coronavirus disease 2019 (COVID-19) pandemic on health was significant worldwide. The measures adopted to limit the spread of the virus had an indirect effect on the epidemiology of other infectious diseases with similar mechanisms of inter-human transmission. The present literature review analyzed the scenario of pediatric acute respiratory infections in the post-lockdown period compared to the pre-pandemic and lockdown periods. The different patterns of viruses' outbreaks were evaluated according to the type of local COVID-19 restrictive measures and to the type of pathogen. Methods: Relevant scientific literature published between March 2020 and November 2024 was identified by means of electronic keyword searches in the PubMed, Scopus, and Cochrane Library databases. Results: Worldwide implementation of non-pharmacological public health interventions aimed at limiting the COVID-19 pandemic resulted in a measurable effect on the circulation of other common respiratory viruses, significantly affecting their usual seasonality. Most viruses significantly reduced their activity during the lockdown period but returned to or exceeded historical levels after discontinuation of preventive non-pharmacological measures. For many respiratory viruses, particularly respiratory syncytial virus, an off-season increase was reported. Conclusions: The non-pharmacological interventions, which effectively helped limit the COVID-19 pandemic, resulted in relevant epidemiologic changes in most common respiratory viruses. Given the different seasonality and clinical severity observed for some pathogens after lockdown, possible future off-season or more severe epidemics should be expected.

Trends and Dynamics of Respiratory Viruses in Hospitalized Children of Fuzhou: Insights Into the Impact of COVID-19 Pandemic Control Measures

Purpose

This study aimed to investigate the prevalence of common respiratory viruses among children with acute respiratory infections in Fuzhou from 2017 to 2023, considering the varying Corona Virus Disease 2019 (COVID-19) epidemic control measures in place.

Patients and Methods

This study retrospectively analyzed the detection of respiratory viruses in children diagnosed with acute respiratory infections at a tertiary hospital in Fuzhou during the study period. The analysis covers three distinct phases: Phase I (2017-2019), Phase II (2020-2022), and Phase III (2023). The subjects of this study included adenovirus (ADV), influenza A virus (Flu A), influenza B virus (Flu B), parainfluenza virus types 1, 2, and 3 (PIV-1, PIV-2, PIV-3), and respiratory syncytial virus (RSV).

Results

A total of 24,838 throat swab samples were collected, resulting in an overall positive detection rate of 17.87% (4439/24,838). The positive detection rates of respiratory viruses among hospitalized children in Phases I, II, and III were 18.51%, 18.27%, and 15.90%, respectively, demonstrating a statistically significant decreasing trend over the years (P < 0.001). Among the detected viruses, RSV, PIV-3, and Flu A were the most prevalent. RSV infections was most common in children under six years of age. Seasonal trends for Flu A, PIV-3, and RSV varied throughout the outbreak; specifically, the detection rate of Flu A increased during March and April in 2023, while RSV detection rebounded sharply from April to June. The incidence of mixed respiratory virus infections was 0.40% (100/24,838), the most common being PIV-3 and RSV.

Conclusion

Using COVID-19 safety rules has helped stop the spread of some viruses in kids. But these rules have not made much difference in how often RSV and PIV-3 viruses show up.

Epidemiological, Clinical, and Genomic Traits of PIV in Hospitalized Children After the COVID-19 Pandemic in Wuhan, China

Human parainfluenza virus (PIV) is a main cause of acute lower respiratory tract infections (ALRTIs), which contributes to childrens' mortality worldwide; however, the epidemiology of PIVs following the SARS-CoV-2 pandemic is still not clarified, and poses risks of potential outbreaks. Herein, we conducted a retrospective observational study from September 26, 2020 to September 30, 2023 to assess PIV epidemiology in Wuhan, China, as well as the clinical characteristics of PIV infections. In total, 14,065 inpatients with ALRTIs were enrolled, of which 936 were identified to have PIV infection. We also obtained 69 PIV3 RNA to reveal its molecular traits. An alteration in PIV season pattern away from spring and summer prevalence was noted, as well as a progressive rise in its detection rate. PIV-related ALRTIs were more prevalent in male patients. PIV3 was the dominant PIV type in recent years. In comparison with the phase before the cancellation of Dynamic Zero-COVID Policy in December 2022, symptoms after its repeal were milder. All Wuhan strains were classified with C3f lineage and possibly evolved from native strains in China. Additionally, some mutations, such as Q499P in protein hemagglutinin-neuraminidase, should be given further attention. In summary, our study demonstrates the clinical characteristics of PIVs and genomic traits of PIV3 in Wuhan, China, thus holds importance for the diagnosis and control of PIV infections in the post-pandemic era.

Healthcare resource utilisation and costs in infants with confirmed respiratory syncytial virus infections: a national population cohort study

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of severe respiratory infections in infants worldwide, significantly affecting their health and contributing to the global healthcare burden. We aimed to examine healthcare resource utilisation patterns and costs for infants under one year old with confirmed RSV infection across subgroups of different gestational ages and health conditions and the cost implications of RSV infections over time, thereby demonstrating the economic burden of the disease.

METHODS

This retrospective cohort study utilised nationwide claims data from the Korea Health Insurance Review and Assessment Service for infants under one year of age with confirmed RSV infection in the first year of life from January 2017 to April 2022. The infants were stratified into three subgroups based on their gestational age and health status: unhealthy preterm, healthy preterm, and full-term infants. A descriptive analysis was conducted to estimate healthcare utilization by type of resource and costs related to the treatment of RSV.

RESULTS

Out of 93,585 RSV infections identified, 31,206 patients met the inclusion criteria; these included 963 unhealthy preterm, 1,768 healthy preterm and 28,475 full-term infants. In our study, 76.3% of the infants with confirmed RSV infection required intensive care, including hospitalisation and more critical interventions such as intensive care unit (ICU) or mechanical ventilation (MV). The total average cost of RSV management was notably higher for unhealthy preterm infants ($ 6,325; 95% confidence interval (CI): $ 5,484-7,165) than for healthy preterm ($ 1,134; 95% CI: $ 1,006 - 1,261) and full-term infants ($ 606; 95% CI: 583-630). Our findings confirmed a significant epidemiological and economic burden, with infants at greater risk-shorter gestational age and poorer health conditions. Furthermore, we observed a marked increase in the total average cost of RSV management during COVID-19, reflecting the complex interplay between RSV and pandemic-related healthcare dynamics.

CONCLUSION

Our findings provide evidence for the significant economic burden of RSV infection among infants, with considerable disparities based on gestational age and health status subgroups. However, RSV prevention policies should also recognise that healthy preterm or full-term infants who receive intensive care face a significant disease burden.

Epidemiology of Human Parainfluenza Virus Infections among Pediatric Patients in Hainan Island, China, 2021-2023

Human parainfluenza viruses (HPIVs) are the leading causes of acute respiratory tract infections (ARTIs), particularly in children. During the COVID-19 pandemic, non-pharmaceutical interventions (NPIs) significantly influenced the epidemiology of respiratory viruses. This study analyzed 19,339 respiratory specimens from pediatric patients with ARTIs to detect HPIVs using PCR or tNGS, focusing on the period from 2021 to 2023. HPIVs were identified in 1395 patients (7.21%, 1395/19,339), with annual detection rates of 6.86% (303/4419) in 2021, 6.38% (331/5188) in 2022, and 7.82% (761/9732) in 2023. Notably, both the total number of tests and HPIV-positive cases increased in 2023 compared to 2021 and 2022. Seasonal analysis revealed a shift in HPIV prevalence from winter and spring in 2021-2022 to spring and summer in 2023. Most HPIV-positive cases were in children aged 0-7 years, with fewer infections among those aged 7-18 years. Since June 2022, HPIV-3 has been the most prevalent serotype (59.55%, 524/880), whereas HPIV-2 had the lowest proportion (0.80%, 7/880). The proportions of HPIV-1 (24.89%, 219/880) and HPIV-4 (15.45%, 136/880) were similar. Additionally, the incidence of co-infections with other common respiratory pathogens has increased since 2021. This study highlights rising HPIV detection rates post-COVID-19 and underscores the need for continuous surveillance of HPIVs to inform public health strategies for future epidemic seasons.

Epidemiology of Respiratory Viruses in Korean Children Before and After the COVID-19 Pandemic: A Prospective Study From National Surveillance System

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic led to a decrease in the seasonal incidence of many respiratory viruses worldwide due to the impact of nonpharmaceutical interventions (NPIs). However, as NPI measures were relaxed, respiratory viral infections re-emerged. We aimed to characterize the epidemiology of respiratory viruses in Korean children during post-COVID-19 pandemic years compared to that before the pandemic.

METHODS

A nationwide prospective ongoing surveillance study has been conducted for detection of respiratory viruses between January 2017 and June 2023. We included data on adenovirus (AdV), human bocavirus (HBoV), human coronavirus (HCoV), human metapneumovirus (HMPV), human rhinovirus (HRV), influenza virus (IFV), parainfluenza virus (PIV), and respiratory syncytial virus (RSV), which were detected in children and adolescents younger than 20 years. We analyzed the weekly detection frequency of individual viruses and the age distribution of the affected children. The study period was divided into prepandemic (2017-2019) and postpandemic (2021-2023) periods.

RESULTS

A total of 19,589 and 14,068 samples were collected in the pre- and postpandemic periods, respectively. The overall detection rate of any virus throughout the study period was 63.1%, with the lowest occurring in the 2nd half of 2020 (50.6%) and the highest occurring in the 2nd half of 2021 (72.3%). Enveloped viruses (HCoV, HMPV, IFV, PIV, and RSV) almost disappeared, but nonenveloped viruses (AdV, HBoV, and HRV) were detected even during the peak of the COVID-19 pandemic. The codetection rate increased from 15.0% prepandemic to 19.1% postpandemic (P < 0.001). During the postpandemic period, a large out-of-season PIV and HMPV epidemic occurred, but the usual seasonality began to be restored in 2023. The mean age of children with each virus detected in 2023 was significantly greater than that in prepandemic years (P = 0.003 and 0.007 for AdV and HCoV, respectively; P < 0.001 for others). The mean age of children with IFV increased in 2022 (11.1 ± 5.2 years) from prepandemic years (7.9 ± 4.6 years) but decreased to 8.7 ± 4.1 years in 2023.

CONCLUSION

With the relaxation of NPI measures, several seasonal respiratory viruses cocirculated with unusual seasonal epidemic patterns and were associated with increasing age of infected children.

Changes in the global hospitalisation burden of respiratory syncytial virus in young children during the COVID-19 pandemic: a systematic analysis

BACKGROUND

The COVID-19 pandemic is reported to have affected the epidemiology of respiratory syncytial virus (RSV), which could have important implications for RSV prevention and control strategies. We aimed to assess the hospitalisation burden of RSV-associated acute lower respiratory infection (ALRI) in children younger than 5 years during the pandemic period and the possible changes in RSV epidemiology from a global perspective.

METHODS

We conducted a systematic literature search for studies published between Jan 1, 2020, and June 30, 2022, in MEDLINE, Embase, Global Health, Web of Science, the WHO COVID-19 Research Database, CINAHL, LILACS, OpenGrey, CNKI, WanFang, and CqVip. We included unpublished data on RSV epidemiology shared by international collaborators. Eligible studies reported data on at least one of the following measures for children (aged <5 years) hospitalised with RSV-associated ALRI: hospital admission rates, in-hospital case fatality ratio, and the proportion of hospitalised children requiring supplemental oxygen or requiring mechanical ventilation or admission to intensive care. We used a generalised linear mixed-effects model for data synthesis to measure the changes in the incidence, age distribution, and disease severity of children hospitalised with RSV-associated ALRI during the pandemic, compared with the year 2019.

FINDINGS

We included 61 studies from 19 countries, of which 14 (23%) studies were from the published literature (4052 identified records) and 47 (77%) were from unpublished datasets. Most (51 [84%]) studies were from high-income countries; nine (15%) were from upper-middle-income countries, one (2%) was from a lower-middle-income country (Kenya), and none were from a low-income country. 15 studies contributed to the estimates of hospitalisation rate and 57 studies contributed to the severity analyses. Compared with 2019, the rates of RSV-associated ALRI hospitalisation in all children (aged 0-60 months) in 2020 decreased by 79·7% (325 000 cases vs 66 000 cases) in high-income countries, 13·8% (581 000 cases vs 501 000 cases) in upper-middle-income countries, and 42·3% (1 378 000 cases vs 795 000 cases) in Kenya. In high-income countries, annualised rates started to rise in 2021, and by March, 2022, had returned to a level similar to 2019 (6·0 cases per 1000 children [95% uncertainty interval 5·4-6·8] in April, 2021, to March, 2022, vs 5·0 cases per 1000 children [3·6-6·8] in 2019). By contrast, in middle-income countries, rates remained lower in the latest period with data available than in 2019 (for upper-middle-income countries, 2·1 cases [0·7-6·1] in April, 2021, to March, 2022, vs 3·4 [1·2-9·7] in 2019; for Kenya, 2·2 cases [1·8-2·7] in 2021 vs 4·1 [3·5-4·7] in 2019). Across all time periods and income regions, hospitalisation rates peaked in younger infants (aged 0 to <3 months) and decreased with increasing age. A significantly higher proportion of children aged 12-24 months were hospitalised with RSV-associated ALRI in high-income and upper-middle-income countries during the pandemic years than in 2019, with odds ratios ranging from 1·30 (95% uncertainty interval 1·07-1·59) to 2·05 (1·66-2·54). No consistent changes in disease severity were observed.

INTERPRETATION

The hospitalisation burden of RSV-associated ALRI in children younger than 5 years was significantly reduced during the first year of the COVID-19 pandemic. The rebound in hospitalisation rates to pre-pandemic rates observed in the high-income region but not in the middle-income region by March, 2022, suggests a persistent negative impact of the pandemic on health-care systems and health-care access in the middle-income region. RSV surveillance needs to be established (or re-established) to monitor changes in RSV epidemiology, particularly in low-income and lower-middle-income countries.

FUNDING

EU Innovative Medicines Initiative Preparing for RSV Immunisation and Surveillance in Europe (PROMISE), Bill & Melinda Gates Foundation, and WHO.

Clinical Characteristics and Severity of Respiratory Syncytial Virus Infection in Korean Children during the Post-COVID-19 Pandemic Period

We aimed to evaluate the clinical features of respiratory syncytial virus (RSV) infection and risk factors for severe RSV disease among Korean children in 2022/2023. A total of 235 children were identified, and 84.3% were hospitalized. Patients under 3 months and 2 years of age accounted for 20.9% and 54.5%, respectively. Pneumonia was diagnosed in 40.9% of children and bronchiolitis in 23.8%. Respiratory support and intensive care were required in 43.4% and 7.7% of patients, respectively. Haemophilus influenzae nasopharyngeal colonization and the presence of underlying disease showed a significant correlation with severity indicators. The clinical impact of RSV infection was high on infants and toddlers, even those having no underlying disease or not being indicated for palivizumab.

Etiology and Clinical Characteristics of Community-Acquired Pneumonia in Korean Children During the Pre-COVID-19 Period, 2015-2020

BACKGROUND

There have been many epidemiologic studies on community-acquired pneumonia (CAP) among children, most of which had substantial limitations. This study investigated the etiologic distribution and clinical characteristics of CAP in Korean children for 5 years before the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

A retrospective analysis of children hospitalized for CAP at 4 referral hospitals during 2015-2020 was performed. Cases in which bronchiolitis was suspected or pulmonary infiltration was not evident on chest radiography (CXR) were excluded. Viruses and atypical bacteria were defined as detected when positive in the polymerase chain reaction test performed for respiratory specimens. Serologic testing result for Mycoplasma pneumoniae was incorporated with strict interpretation. Pyogenic bacteria were included only when cultured in blood, pleural fluid, or bronchoalveolar lavage, but those cultured in endotracheal aspirate or sputum when the case was clinically evident bacterial pneumonia were also included.

RESULTS

A total of 2,864 cases of suspected pneumonia were selected by diagnosis code and CXR findings. Medical chart and CXR review excluded nosocomial pneumonia and cases without evident infiltration, resulting in 517 (18.1%) CAP cases among 489 children. Regarding clinical symptoms, high fever was present in 59.4% and dyspnea in 19.9% of cases. Respiratory support was required for 29.2% of patients, including mechanical ventilation for 3.9%. Pathogens were detected in 49.9% of cases, with viruses in 32.3%, atypical bacteria in 17.8%, and pyogenic bacteria in 2.3% of cases. As single pathogens, M. pneumoniae (16.8%) and respiratory syncytial virus (RSV, 13.7%) were the most common. Parenteral β-lactam and macrolide antibiotics were administered in 81.6% and 50.7% of cases, respectively. A total of 12 (2.3%) cases resulted in poor outcomes, including 3 deaths.

CONCLUSION

M. pneumoniae and RSV were the most commonly detected pathogens of pediatric CAP, which was selected by strict clinical and radiologic criteria. It is necessary to carefully decide whether to use parenteral antibiotics based on the epidemiology and clinical features of CAP in children.

Nasal CPAP in the Pediatric Ward to Reduce PICU Admissions for Severe Bronchiolitis?

In treating acute bronchiolitis in infants, the decision to use continuous positive airway pressure (CPAP) often involves infant referral from the pediatric ward to the pediatric intensive care unit (PICU). We present our experience of CPAP use in a general pediatric ward, aiming to reduce the pressure on the PICU in recent outbreaks of bronchiolitis. Clinical data of patients less than 12 months of age and admitted for bronchiolitis from 1 October 2021 to 31 March 2023 were retrospectively collected. Of 82 infants admitted for bronchiolitis, 16 (19%) were treated with nasal CPAP (nCPAP group); of the remaining 66, 21 (26%) were treated with a low-flow nasal cannula (LFNC) only, 1 (1%) was also treated a with high-flow nasal cannula (HFNC), 12 (15%) were treated with an HFNC only, and 41 (50%) were treated without oxygen support (no-nCPAP group). Overall, coinfection with RSV and SARS-CoV-2 was observed in three patients and SARS-CoV-2 infection was observed in two patients. None of them required any type of oxygen support. Only 3/16 (19%) infants in the nCPAP group were referred to the PICU due to worsening clinical conditions despite nCPAP support. In our experience of treating epidemic bronchiolitis, nCPAP can be safely managed in a general pediatric ward, thus reducing the burden of admissions to the PICU. Training and regular updating of the pediatric staff, careful monitoring of the patient, and close cooperation with the PICU were instrumental for our team.

Machine learning forecasts for seasonal epidemic peaks: Lessons learnt from an atypical respiratory syncytial virus season

Seasonal peaks in infectious disease incidence put pressures on health services. Therefore, early warning of the timing and magnitude of peak activity during seasonal epidemics can provide information for public health practitioners to take appropriate action. Whilst many infectious diseases have predictable seasonality, newly emerging diseases and the impact of public health interventions can result in unprecedented seasonal activity. We propose a Machine Learning process for generating short-term forecasts, where models are selected based on their ability to correctly forecast peaks in activity, and can be useful during atypical seasons. We have validated our forecasts using typical and atypical seasonal activity, using respiratory syncytial virus (RSV) activity during 2019-2021 as an example. During the winter of 2020/21 the usual winter peak in RSV activity in England did not occur but was 'deferred' until the Spring of 2021. We compare a range of Machine Learning regression models, with alternate models including different independent variables, e.g. with or without seasonality or trend variables. We show that the best-fitting model which minimises daily forecast errors is not the best model for forecasting peaks when the selection criterion is based on peak timing and magnitude. Furthermore, we show that best-fitting models for typical seasons contain different variables to those for atypical seasons. Specifically, including seasonality in models improves performance during typical seasons but worsens it for the atypical seasons.

Impact of public health measures and new introducing variants on Respiratory syncytial virus recrudescence in Taiwan during the COVID-19 pandemic

OBJECTIVES

Respiratory syncytial virus (RSV) causes clinically significant distress in children and adults. Non-pharmaceutical interventions against SARS-CoV-2 have affected the seasonal activity of common respiratory pathogens. This seems exceptionally true regarding RSV's seasonal circulation, hence we have investigated the changes in the epidemiology of RSV in Taiwan during the pandemic.

MATERIALS

A prospective surveillance of RSV among hospitalized children was carried out between 2020 and 2022 in central Taiwan. Of all PCR-detected RSV, genotype and evolutionary analysis were further investigated. Demographics and clinical features were compared between each outbreak.

RESULTS

Throughout the consecutive three years of the SARS-CoV-2 pandemic, RSV outbreaks took place in Taiwan first in 2020 and a second time in 2022. We enrolled 80 and 105 hospitalized child cases, in each surge respectively. The RSV G protein genomic analysis revealed that RSV ON1 and RSV BA9 were separately contributing to these two outbreaks, and evolutionary evidence indicated these RSV variants are new to Taiwan, with their own featured sets of mutations. Clinically, a shift in age of RSV infected children was found, but the clinical severity was not worse and remained independent of RSV genotype.

CONCLUSIONS

There were two delayed RSV surges after the relaxation of public measures during the pandemic in Taiwan, and both outbreaks were driven by new RSV genetic variants rather than cryptic circulation of the previous genetic clusters in Taiwan. These findings highlight the importance of continued surveillance on the trend and evolution of RSV after the COVID-19 pandemic.

Epidemiology of Human Parainfluenza Virus Type 3 and Respiratory Syncytial Virus Infections in the Time of Coronavirus Disease 2019: Findings From a Household Cohort in Maryland

BACKGROUND

During the coronavirus disease 2019 (COVID-19) pandemic, human parainfluenza type 3 (HPIV-3) and respiratory syncytial virus (RSV) circulation increased as nonpharmaceutical interventions were relaxed. Using data from 175 households (n = 690 members) followed between November 2020 and October 2021, we characterized HPIV-3 and RSV epidemiology in children aged 0-4 years and their households.

METHODS

Households with ≥1 child aged 0-4 years were enrolled; members collected weekly nasal swabs (NS) and additional NS with respiratory illnesses (RI). We tested NS from RI episodes in children aged 0-4 years for HPIV-3, RSV, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using reverse-transcriptase polymerase chain reaction (RT-PCR). Among children with HPIV-3 or RSV infection, we tested contemporaneous NS from household members. We compared incidence rates (IRs) of RI with each virus during epidemic periods and identified household primary cases (the earliest detected household infection), and associated community exposures.

RESULTS

41 of 175 (23.4%) households had individuals with HPIV-3 (n = 45) or RSV (n = 46) infections. Among children aged 0-4 years, RI IRs /1000 person-weeks were 8.7 [6.0, 12.2] for HPIV-3, 7.6 [4.8, 11.4] for RSV, and 1.9 [1.0, 3.5] for SARS-CoV-2. Children aged 0-4 years accounted for 35 of 36 primary HPIV-3 or RSV cases. Children attending childcare or preschool had higher odds of primary infection (odds ratio, 10.81; 95% confidence interval, 3.14-37.23).

CONCLUSIONS

Among children aged 0-4 years, RI IRs for HPIV-3 and RSV infection were 4-fold higher than for SARS-CoV-2 during epidemic periods. HPIV-3 and RSV were almost exclusively introduced into households by young children.

Epidemiological characteristics of respiratory viruses in hospitalized children during the COVID-19 pandemic in southwestern China

Background

Multinational studies have reported that the implementation of nonpharmaceutical interventions (NPIs) to control severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission coincided with the decline of other respiratory viruses, such as influenza viruses and respiratory syncytial virus.

Objective

To investigate the prevalence of common respiratory viruses during the coronavirus disease 2019 (COVID-19) pandemic.

Methods

Respiratory specimens of children with lower respiratory tract infections (LRTIs) hospitalized at the Children's Hospital of Chongqing Medical University from January 1, 2018 to December 31, 2021 were collected. Seven common pathogens, including respiratory syncytial virus (RSV), adenovirus (ADV), influenza virus A and B (Flu A, Flu B), and parainfluenza virus types 1-3 (PIV1-3), were detected by a multiplex direct immunofluorescence assay (DFA). Demographic data and laboratory test results were analyzed.

Results

1) A total of 31,113 children with LRTIs were enrolled, including 8141 in 2018, 8681 in 2019, 6252 in 2020, and 8059 in 2021.The overall detection rates decreased in 2020 and 2021 (P < 0.001). The detection rates of RSV, ADV, Flu A, PIV-1, and PIV-3 decreased when NPIs were active from February to August 2020, with Flu A decreasing most predominantly, from 2.7% to 0.3% (P < 0.05). The detection rates of RSV and PIV-1 resurged and even surpassed the historical level of 2018-2019, while Flu A continued decreasing when NPIs were lifted (P < 0.05). 2) Seasonal patterns of Flu A completely disappeared in 2020 and 2021. The Flu B epidemic was observed until October 2021 after a long period of low detection in 2020. RSV decreased sharply after January 2020 and stayed in a nearly dormant state during the next seven months. Nevertheless, the detection rates of RSV were abnormally higher than 10% in the summer of 2021. PIV-3 decreased significantly after the COVID-19 pandemic; however, it atypically surged from August to November 2020.

Conclusion

The NPIs implemented during the COVID-19 pandemic affected the prevalence and seasonal patterns of certain viruses such as RSV, PIV-3, and influenza viruses. We recommend continuous surveillance of the epidemiological and evolutionary dynamics of multiple respiratory pathogens, especially when NPIs are no longer necessary.

Respiratory Syncytial Virus Pediatric Hospitalization in the COVID-19 Era

Respiratory syncytial virus (RSV) globally affects the population, mainly young children, potentially causing hospitalization. During the COVID-19 pandemic, non-pharmacological measures interfered with the circulation of most respiratory viruses. Then, with the discontinuation of restrictive measures, a new scenario appeared. With this scoping review, we want to globally explore whether the RSV paediatric hospitalization rate was influenced by COVID-19. This scoping review was performed according to PRISMA guidelines on PubMed using the Mesh terms "Respiratory Syncytial Viruses"[Mesh] AND "COVID-19"[Mesh] OR "SARS-CoV-2"[Mesh]. Among them, we identified studies pertaining to children and adolescents up to 18 years old hospitalized for RSV, including 18 records in the revision. With the onset of the COVID-19 pandemic, a drastic reduction in RSV hospitalization among the pediatric population in 2020-2021 season has been observed in the Northern and Southern hemispheres. After the relaxing of restrictive measures, unexpected outbreaks happened, leading to increased hospitalization and occupation of pediatric intensive care units.