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

Abu-Raya B, Reicherz F, Michalski C, Majdoubi A, Golding L, Vienta M, Granoski M, Stojic A, Marchant DJ, Lavoie PM. Loss of severe respiratory syncytial virus infection-associated antibody function during the peak of the COVID-19 pandemic mitigation measures. medRxiv 2023 Aug 2. doi:

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 preprint and not-yet peer-reviewed, found that the almost complete absence of RSV circulation during the peak of COVID-19 pandemic mitigation measures led to waning antibody-mediated and cellular responses that protect against severe respiratory syncytial virus (RSV) infection. Since these RSV antibody functions are the main way for young children to fend off an RSV infection, this suggests that if pregnant people aren’t exposed to the RSV virus regularly, the protection against the virus that can be transferred to their baby during pregnancy may be weakened. This study was led by Dr. Pascal Lavoie and Dr. Bahaa Abu-Raya, a post-doctoral fellow in Dr. Lavoie’s research group (University of British Columbia).

Key findings:

  • During the first year of the COVID-19 pandemic, low circulating levels of RSV led to the reduction of important antibody functions against RSV.
  • RSV antibody protection decreases without ongoing exposure to the virus.
  • Studies have linked waning RSV antibody functions mediated through the so-called “Fc portion”, that are essential for cellular responses, to the increased likelihood of more severe lower respiratory tract RSV infections.

This study highlights the importance of ongoing viral exposure to maintain strong antibody function, especially in vulnerable groups such as infants and older children. Further studies are needed to replicate these findings in different health jurisdictions.

Samples were collected from women of child-bearing age (18-to-51-years-old) during the complete pandemic-related lockdown in British Columbia, Canada, from May 2020 to June 2020 (early in the pandemic), and from February 2021 to May 2021 (one year after the pandemic started).