key: cord-0901887-rsmfergc authors: Delestrain, Céline; Danis, Kostas; Hau, Isabelle; Behillil, Sylvie; Billard, Marie‐Noëlle; Krajten, Leyla; Cohen, Robert; Bont, Louis; Epaud, Ralph title: Impact of COVID‐19 social distancing on viral infection in France: A delayed outbreak of RSV date: 2021-09-02 journal: Pediatr Pulmonol DOI: 10.1002/ppul.25644 sha: 600656cdfc3ade5ff2c0ecc9e52fcf88e210edb4 doc_id: 901887 cord_uid: rsmfergc INTRODUCTION: COVID‐19 pandemic and associated lockdown measures have deeply modified the natural course of seasonal viral infections, such as respiratory syncytial virus (RSV). METHODS: We analyzed French national data from three networks: emergency departments (ED) of French hospitals, general practitioners (GP), and hospital laboratories. We compared the number of ED or GP visits for bronchiolitis in children <2 years of age, and the percentage of RSV positive tests in the 2020 to 2021 season with those of the two previous seasons (2018–2019 and 2019–2020). We used time series of the previous 5 years to calculate epidemic thresholds. RESULTS: During the 2020–2021 season, the epidemic begun in February (Week 05) in the Ile de France (Paris and suburbs) region, 12 weeks later compared with the previous seasons and progressively spread across all the French metropolitan regions. The highest number of bronchiolitis cases in 2021 (Week 12) occurred 10–12 weeks after the previous seasonal peaks of previous seasons, but the number of cases remained lower than in the previous seasonal peaks. CONCLUSION: We identified a delayed RSV epidemic in the period that usually corresponds at the end of the epidemic season, raising concerns for the burden of RSV in the already strained healthcare systems during the COVID‐19 pandemic. during the COVID-19 pandemic have deeply modified the natural epidemic course of common childhood respiratory infections, including those caused by respiratory syncytial virus (RSV) in several European and Southern Hemisphere countries. [3] [4] [5] RSV is considered the major pathogen causing severe lower respiratory tract infections, mainly acute bronchiolitis, in infants and young children, 6 leading to seasonal epidemics with one to two epidemics each year. 7, 8 It causes substantial morbidity and hospitalization for acute bronchiolitis in children younger than 5 years of age and especially in the first year of life 9,10 with a mortality estimated between 66,000 and 199,000 deaths worldwide every year. 8 In March 2020, the spread of SRAS-CoV-2 infection increased dramatically in France, overloading health systems. A first stringent lockdown was ordered on March 17 to limit indoor and outdoor social interactions. All nonessential public places, including, restaurants, cafés, cinemas, nightclubs together with schools and children day care centers were closed. The lockdown was extended to May 11, while physical distancing, wearing a mask in public places, and hand hygiene continued to be recommended. SARS-CoV-2 transmission substantially decreased and was limited for 14 weeks during the summer (Weeks 20-34). Following a further increased incidence of SARS-CoV-2 infections, France implemented a second nationwide but less stringent lockdown from October 30 to December 15, cluding the closure of all nonessential businesses, but schools and day care centers remained open, and activities for children younger than 11 years of age were not restricted. In this context, we aimed to assess the course of RSV infections in France during 2020-2021 season and compare them with the two previous RSV seasons. All records are transmitted daily and anonymously to Santé publique France in line with national patient confidentiality rules. 13 We compared the number of ED visits, GP visits, and hospitalizations for bronchiolitis in children <2 years of age, as well as the percentage of RSV positive tests in the 2020-2021 season with those of the two previous seasons (2018-2019 and 2019-2020). The methods for calculating the epidemic threshold were described elsewhere. 14 Briefly, to calculate the baseline levels and prediction intervals, time series was used fitting three different models (periodic regression, robust periodic regression, and Markov models) on the weekly numbers of bronchiolitis cases reported via Oscour or SOS Medecins during the previous 5 years (6 models). An alarm was generated when the number of cases exceeded the 95% prediction limit. An epidemic phase was declared when at least one alarm was generated for both Oscour and SOS Médecins data or at least two alarms for Oscour data, and a preepidemic when one alarm was only detected. 15 We report a delayed start of the bronchiolitis outbreak in France and an ongoing increase in the period that usually corresponds to the end of the epidemic season. During the 2020-2021 winter season, the RSV epidemic, which usually peaks in mid-December, started in January with a peak shifted by almost 3 months. However, the number of bronchiolitis cases remained much lower than that observed in the previous seasons. Meanwhile, the European center for disease prevention and control (ECDC) surveillance data 16 indicated that this RSV resurgence was almost limited to France. In Europe, RSV circulation remained very low, with only some countries reporting few sporadic cases since the start of the winter season (Belgium, Germany, Spain, Sweden). 16 The data that support the findings of this study are available from the corresponding author upon reasonable request. http://orcid.org/0000-0002-5577-5327 Kostas Danis https://orcid.org/0000-0001-6727-7344 Ralph Epaud http://orcid.org/0000-0003-3830-1039 Epidemiology and clinical presentation of children hospitalized with SARS-CoV-2 infection in suburbs of Paris Factors associated with severe SARS-CoV-2 infection Bronchiolitis in COVID-19 times: a nearly absent disease? Collateral impact of COVID-19: why should children continue to suffer? 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