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.

Background Statistical modelling studies based on excess morbidity and mortality are important for understanding RSV disease burden for age groups that are less frequently tested for RSV. We aimed to understand the full age spectrum of RSV morbidity and mortality burden based on statistical modelling studies, as well as the value of modelling studies in RSV disease burden estimation. Methods The databases Medline, Embase and Global Health were searched to identify studies published between January 1, 1995, and December 31, 2021, reporting RSV-associated excess hospitalisation or mortality rates of any case definitions using a modelling approach. All reported rates were summarised using median, IQR (Interquartile range) and range by age group, outcome and country income group; where applicable, a random-effects meta-analysis was conducted to combine the reported rates. We further estimated the proportion of RSV hospitalisations that could be captured in clinical databases. Results A total of 32 studies were included, with 26 studies from high-income countries. RSV-associated hospitalisation and mortality rates both showed a U-shape age pattern. Lowest and highest RSV acute respiratory infection (ARI) hospitalisation rates were found in 5–17 years (median: 1.6/100,000 population, IQR: 1.3–18.5) and < 1 year (2235.7/100,000 population, 1779.1–3552.5), respectively. Lowest and highest RSV mortality rates were found in 18–49 years (0.1/100,000 population, 0.06–0.2) and ≥ 75 years (80.0/100,000 population, 70.0–90.0) for high-income countries, respectively, and in 18–49 years (0.3/100,000 population, 0.1–2.4) and < 1 year (143.4/100,000 population, 143.4–143.4) for upper-middle income countries. More than 70% of RSV hospitalisations in children < 5 years could be captured in clinical databases whereas less than 10% of RSV hospitalisations could be captured in adults, especially for adults ≥ 50 years. Using pneumonia and influenza (P&I) mortality could potentially capture half of all RSV mortality in older adults but only 10–30% of RSV mortality in children. Conclusions Our study provides insights into the age spectrum of RSV hospitalisation and mortality. RSV disease burden using laboratory records alone could be substantially severely underreported for age groups ≥ 5 years. Our findings confirm infants and older adults should be prioritised for RSV immunisation programmes. Trial registration PROSPERO CRD42020173430.

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.