Non-pharmaceutical interventions (NPIs) were widely introduced to combat the COVID-19 pandemic. These interventions also likely led to substantially reduced activity of respiratory syncytial virus (RSV). From late 2020, some countries observed out-of-season RSV epidemics. Here, we analyzed the role of NPIs, population mobility, climate, and SARS-CoV-2 circulation in RSV rebound through a time-to-event analysis across 18 countries. Full (re)-opening of schools was associated with an increased risk for RSV rebound (HR = 23.29 [95% CI: 1.09–495.84]); every 5°C increase in temperature was associated with a decreased risk (HR = 0.63 [0.40–0.99]). There was an increasing trend in the risk for RSV rebound over time, highlighting the role of increased population susceptibility. No other factors were found statistically significant. Further analysis suggests increasing population susceptibility and full (re)-opening of schools could both override the counter-effect of high temperatures, which explains the out-of-season RSV epidemics during the COVID-19 pandemic.

Background With the easing of COVID-19 non-pharmaceutical interventions, the resurgence of both influenza and respiratory syncytial virus (RSV) was observed in several countries globally after remaining low in activity for over a year. However, whether co-infection with influenza or RSV influences disease severity in COVID-19 patients has not yet been determined clearly. We aimed to understand the impact of influenza/RSV co-infection on clinical disease severity among COVID-19 patients. Methods We conducted a systematic literature review of publications comparing the clinical severity between the co-infection group (ie, influenza/RSV with SARS-CoV-2) and mono-infection group (ie, SARS-CoV-2), using the following four outcomes: need or use of supplemental oxygen, intensive care unit (ICU) admission, mechanical ventilation, and deaths. We summarized the results by clinical outcome and conducted random-effect meta-analyses where applicable. Results Twelve studies reporting a total of 7862 COVID-19 patients were included in the review. Influenza and SARS-CoV-2 co-infection were found to be associated with a higher risk of ICU admission (five studies, odds ratio (OR) = 2.09, 95% confidence interval (CI) = 1.64-2.68) and mechanical ventilation (five studies, OR = 2.31, 95% CI = 1.10-4.85). No significant association was found between influenza co-infection and need/use of supplemental oxygen or deaths among COVID-19 patients (four studies, OR = 1.04, 95% CI = 0.37-2.95; 11 studies, OR = 1.41, 95% CI = 0.65-3.08, respectively). For RSV co-infection, data were only sufficient to allow for analyses for the outcome of deaths, and no significant association was found between RSV co-infection and deaths among COVID-19 patients (three studies, OR = 5.27, 95% CI = 0.58-47.87). Conclusions Existing evidence suggests that co-infection with influenza might be associated with a 2-fold increase in the risk for ICU admission and for mechanical ventilation among COVID-19 patients whereas evidence is limited on the role of RSV co-infection. Co-infection with influenza does not increase the risk of death in COVID-19 patients. Registration PROSEPRO CRD42021283045.

Introduction Previous studies reported inconsistent findings regarding the association between respiratory syncytial virus (RSV) subgroup distribution and timing of RSV seasonal epidemics, possibly due to not accounting for confounders such as meteorological factors. We aimed to improve the understanding of the association through a global-level systematic analysis that accounted for these potential confounders. Methods We compiled published data on RSV seasonality through a systematic literature review, and supplemented with unpublished data shared by international collaborators. RSV seasonal characteristics were defined for each study-year based on the annual cumulative proportion (ACP) of RSV-positive cases, with ACP of 10% and 90% being defined as season onset and offset, respectively. Linear regression models with study-level clustered standard errors were conducted to analyse the association of proportion of RSV-A with the corresponding RSV season onset and offset separately, while accounting for meteorological factors. Results We included a total of 36 studies from 36 sites in 20 countries, which cumulatively provided data for 179 study-years in 1995–2019. Overall, year-on-year variations in RSV season onset, offset, and duration were generally comparable among tropical, sub-tropical, and temperate regions. Regression analysis by latitude groups showed that RSV subgroup distribution was not significantly associated with RSV season onset or offset globally; the only exception was for RSV season offset in the tropics in one model, possibly by chance. Models that included both RSV subgroup distribution and meteorological factors only jointly explained 2–4% of the variations in RSV season onset and offset. Conclusion Globally, RSV subgroup distribution had negligible impact on the RSV seasonal characteristics. RSV subgroup distribution and meteorological factors jointly could only explain limited year-on-year variations in RSV season onset and offset. The role of population susceptibility, mobility, and viral interference should be examined in future studies.

IntroductionChildcare centre is considered a high-risk setting for transmission of respiratory viruses. Further evidence is needed to understand the risk of transmission in childcare centres. To this end, we established the DISeases TrANsmission in ChildcarE (DISTANCE) study to understand the interaction among contact patterns, detection of respiratory viruses from environment samples and transmission of viral infections in childcare centres.Methods and analysisThe DISTANCE study is a prospective cohort study in multiple childcare centres of Jiangsu Province, China. Study subjects will be childcare attendees and teaching staff of different grades. A range of information will be collected from the study subjects and participating childcare centres, including attendance, contact behaviours (collected by onsite observers), respiratory viral infection (weekly respiratory throat swabs tested by multiplex PCR), presence of respiratory viruses on touch surfaces of childcare centres and weekly follow-up survey on respiratory symptoms and healthcare seeking among subjects tested positive for any respiratory viruses. Detection patterns of respiratory viruses from study subjects and environment samples, contact patterns, and transmission risk will be analysed by developing statistical and mathematical models as appropriate. The study has been initiated in September 2022 in 1 childcare centre in Wuxi City, with a total of 104 children and 12 teaching staff included in the cohort; data collection and follow-up is ongoing. One more childcare centre in Nanjing City (anticipated to include 100 children and 10 teaching staff) will start recruitment in 2023.Ethics and disseminationThe study has received ethics approval from Nanjing Medical University Ethics Committee (No. 2022-936) and ethics approval from Wuxi Center for Disease Control and Prevention Ethics Committee (No. 2022-011). We plan to disseminate the study findings mainly through publications in peer-reviewed journals and presentations in academic conferences. Aggregated research data will be shared freely to researchers.

Aim: To understand the impact of influenza/RSV co-infection on clinical disease severity among COVID-19 patients. Methods: We conducted a systematic literature review of publications comparing the clinical severity between the co-infection group (i.e., influenza/RSV with SARS-CoV-2) and mono-infection group (i.e., SARS-CoV-2), using the following four outcomes: need or use of supplemental oxygen, intensive care unit (ICU) admission, mechanical ventilation and deaths. We summarized the results by clinical outcome and conducted random-effect meta-analyses, where applicable. Results: Twelve studies reporting a total of 7862 COVID-19 patients were included in the review. Influenza and SARS-CoV-2 co-infection was found to be associated with a higher risk of ICU admission (5 studies, OR: 2.09, 95% CI: 1.64-2.68) and mechanical ventilation (5 studies, OR: 2.31, 95% CI: 1.10-4.85). No significant association was found between influenza co-infection and need/use of supplemental oxygen or deaths among COVID-19 patients (4 studies, OR: 1.04, 95% CI: 0.37-2.95; 11 studies, OR: 1.41, 95% CI: 0.65-3.08, respectively). For RSV co-infection, data were only sufficient to allow for analyses for the outcome of deaths, and no significant association was found between RSV co-infection and deaths among COVID-19 patients (3 studies, OR: 5.27, 95% CI: 0.58-47.87). Conclusions: Existing evidence suggests that co-infection with influenza might be associated with a 2-fold increase in the risk for ICU admission and for mechanical ventilation among COVID-19 patients whereas evidence is limited on the role of RSV co-infection. Co-infection with influenza does not increase the risk of death in COVID-19 patients.