Key Points

In Nouvelle-Aquitaine, the bronchiolitis epidemic began in week 41 of 2021 (October 11–17, 2021), peaked in week 48 of 2021 (November 29–December 5, 2021), and ended in the first week of 2022 (January 3–9, 2022). It lasted 13 weeks, comparable to previous seasons, except for the atypical 2020–21 season, which was marked by a very late start, low intensity, and a short epidemic period.

The severity of the 2021–2022 epidemic season was more moderate than in the 2018–19 and 2019–20 seasons, with a slightly lower proportion of hospitalizations than in previous years (45%). The majority of hospitalized bronchiolitis cases were children under 3 months of age (47%), as in previous seasons, except for the 2020-2021 season, when this proportion was lower.

Respiratory syncytial virus (RSV) circulation began as early as week 40 of 2021 (October 4–10, 2021) and remained very active from week 42 (October 18–24) through week 51 (December 20–26), peaking in week 49 (December 6–12), when nearly 20% of respiratory specimens tested by laboratories at the region’s three university hospitals were positive for RSV.

Since week 04-2022 (January 24–30), emergency department visits for bronchiolitis have remained at a low to moderate level, with approximately 4% to 6% of visits for bronchiolitis among children under 2 years of age, and a decrease in the proportion of bronchiolitis cases among hospitalizations (approximately 10% in week 10-2022 – March 7–13). Activity at SOS Médecins clinics for bronchiolitis also remains at a low to moderate level, with between 3% and 4%
of procedures involving children under 2 years of age.