This is a summary, written by members of the CITF Secretariat, of:

Paramo MV, Ngo LPN, Abu-Raya B, Reicherz F, Xu RY, Bone JN, Srigley JA, Solimano A, Goldfarb DM, Skowronski DM, Lavoie PM. Respiratory syncytial virus epidemiology and clinical severity before and during the COVID-19 pandemic in British Columbia, Canada: a retrospective observational study. Lancet Reg. Health – Am. 

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study, published in The Lancet Regional Health – Americas, reported an increase in respiratory syncytial virus (RSV) infections among children over 2 years old during 2021–22, the first RSV season after a prolonged lack of virus circulation, compared to pre-pandemic years (2017-2020). In addition, hospitalisations due to RSV increased dramatically in the following year (2022–23), although the number of children with severe outcomes (mechanical ventilation and/or death) did not increase. This study was led by Dr. Pascal Lavoie (University of British Columbia) and Dr. Marina Viñeta Paramo, a physician and PhD candidate in Dr. Lavoie’s research group at the University of British Columbia.

Key findings:

  • During the 2021-2022 and 2022-2023 periods, British Columbia experienced 5.4-fold and 4.7-fold increases, respectively, in positive RSV tests province-wide, compared to equivalent pre-pandemic periods from September 1, 2017, to August 31, 2020.
  • Mirroring these observed trends in positive RSV cases across BC among both children and adults, the number of RSV cases in children seen at BC Children’s Hospital also rose, with increases during both the 2021-2022 and the 2022-2023 periods.
  • The median age of children with RSV at BC Children’s Hospital increased from 8.7 months in 2017-2018 to 19.6 months in 2022-2023.
  • More children were hospitalised in 2022–2023 than annually between 2017–2020 and in 2021–2022. There was no detected increase in hospitalisations or intensive care unit (ICU) admissions in children born prematurely, or with respiratory or cardiac health conditions.
  • The increase in RSV severity outcomes, including need for intensive care respiratory therapies and longer lengths of stay, seen at the only paediatric hospital in British Columbia suggests belated severity trends that may be related to a loss of RSV seasonality during the pandemic.

Altogether, this study shows that BC experienced two atypical RSV seasons after a prolonged absence of virus circulation. This is consistent with an accumulation, during this period, in the pool of immunologically vulnerable children. The study also highlights the importance of ongoing monitoring of RSV cases, to allow careful planning of preventive interventions and in the availability of hospital resources.

This was a retrospective study of reported respiratory syncytial virus (RSV) cases in British Columbia over the period from September 1, 2017 to May 15, 2023, along with analysis of RSV-related hospitalization data for all children under 18 years old who tested positive for RSV at the BC’s Children’s Hospital.