Bronchiolitis epidemics in France during the SARS-CoV-2 pandemic: The 2020-2021 and 2021-2022 seasons.

OBJECTIVES: We described bronchiolitis epidemics during the 2020-2021 and 2021-2022 seasons in France and their interaction with the COVID outbreak. PATIENTS AND METHODS: Data on family physician (FP) visits, emergency department (ED) visits, hospitalizations for bronchiolitis for children˂2 years, and hospital virological data were analyzed and compared with previous seasons (2015-2020). RESULTS: The 2020-2021 epidemic arrived very late, and its impact was lower than in previous seasons (2015-2020) (FP visits: -23%, ED visits: -38%, and hospitalizations: -30%). The 2021-2022 epidemic started early (week 40) and lasted for a relatively long time (13 weeks). The impact was higher than in 2015-2020 (FP visits: +13%, ED visits: +34%, hospitalizations: +28%). CONCLUSION: Findings from the 2020-2021 epidemic may be linked to the implementation of non-pharmaceutical COVID-19 prevention measures. For 2021-2022, findings may be linked to an "immunity debt" resulting from the lower impact of the previous season.

Surgical mask to prevent influenza transmission in households: a cluster randomized trial.

BACKGROUND: Facemasks and respirators have been stockpiled during pandemic preparedness. However, data on their effectiveness for limiting transmission are scarce. We evaluated the effectiveness of facemask use by index cases for limiting influenza transmission by large droplets produced during coughing in households. METHODOLOGY AND PRINCIPAL FINDINGS: A cluster randomized intervention trial was conducted in France during the 2008-2009 influenza season. Households were recruited during a medical visit of a household member with a positive rapid influenza A test and symptoms lasting less than 48 hours. Households were randomized either to the mask or control group for 7 days. In the intervention arm, the index case had to wear a surgical mask from the medical visit and for a period of 5 days. The trial was initially intended to include 372 households but was prematurely interrupted after the inclusion of 105 households (306 contacts) following the advice of an independent steering committee. We used generalized estimating equations to test the association between the intervention and the proportion of household contacts who developed an influenza-like illness during the 7 days following the inclusion. Influenza-like illness was reported in 24/148 (16.2%) of the contacts in the intervention arm and in 25/158 (15.8%) of the contacts in the control arm and the difference between arms was 0.40% (95%CI: -10% to 11%, P = 1.00). We observed a good adherence to the intervention. In various sensitivity analyses, we did not identify any trend in the results suggesting effectiveness of facemasks. CONCLUSION: This study should be interpreted with caution since the lack of statistical power prevents us to draw formal conclusion regarding effectiveness of facemasks in the context of a seasonal epidemic. TRIAL REGISTRATION: clinicaltrials.gov NCT00774774.