Seasonal and inter-seasonal RSV activity in the European Region during
the COVID-19 pandemic from Autumn 2020 to Summer 2022
Abstract
Background: The emergence of the Severe Acute Respiratory Syndrome
Coronavirus 2 (SARS-CoV-2) in early 2020 and subsequent implementation
of public health and social measures (PHSM) disrupted the epidemiology
of respiratory viruses. This work describes the epidemiology of RSV
observed during two winter seasons (weeks 40 to 20) and inter-seasonal
periods (weeks 21 to 39) during the pandemic between October 2020 and
September 2022. Methods: Using data submitted to The European
Surveillance System (TESSy) by countries or territories in the World
health Organization (WHO) European Region between weeks 40/2020 and
39/2022, we aggregated country-specific weekly RSV counts of sentinel,
non-sentinel and Severe Acute Respiratory Infection (SARI) surveillance
specimens and calculated percentage positivity. Results for both 2020/21
and 2021/22 seasons and inter-seasons were compared to pre-pandemic
2016/17 to 2019/20 seasons and inter-seasons. Results: Although more
specimens were tested than in pre-COVID-19 pandemic seasons, very few
RSV detections were reported during the 2020/21 season in all
surveillance systems. During the 2021 inter-season, a gradual increase
in detections was observed in all systems. In 2021/22, all systems saw
early peaks of RSV infection, and during the 2022 inter-seasonal period,
patterns of detections were closer to those seen before the COVID-19
pandemic. Conclusion: RSV surveillance continued throughout the COVID-19
pandemic, with an initial reduction in transmission, followed by very
high and out-of-season RSV circulation (summer 2021) and then an early
start of the 2021/22 season. RSV circulation during the 2022/23 season
had not yet normalised.