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

Reicherz F, Xu RY, Abu-Raya B, Majdoubi A, Michalski C, Golding L, Stojic A, Vineta M, Granoski M, Cieslak Z, Chacko A, Desai N, Sekirov I, Marchant DJ, Lavoie PM. Waning immunity against respiratory syncytial virus during the COVID-19 pandemic. Journal of Infectious Diseases. May 7, 2022. Doi: org/10.1093/infdis/jiac192.

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

Where an average of 1,450 cases of respiratory syncytial virus (RSV)Respiratory syncytial virus (RSV) is a viral infection that causes seasonal respiratory illness, particularly in young children and infants. Symptoms include congestion and inflammation of the lungs and upper airways. are reported each year in British Columbia, only five cases were reported in the province in 2020-2021 due largely to drastically reduced interactions while provincial lockdowns were in effect. In a paper published in the Journal of Infectious Diseases, Dr. Pascal Lavoie and his team from the University of British Columbia discovered that infants and women of childbearing age exhibited a profound loss of antibodies against RSV after one year of the COVID-19 pandemic. Natural waning of RSV immunity and lack of exposure to the virus due to pandemic mitigation measures are likely contributors. These results have important implications for the recent resurgences of RSV infections.

Key Findings:

  • Antibodies recognizing RSV were roughly 15 times lower in infants sampled in 2021 compared to those sampled in 2020.
  • Levels of RSV neutralization were 3.4 times lower in infants sampled in 2021 compared to those sampled the year prior, even after adjusting for age.
  • RSV antibody levels in women of childbearing age (18-51 years old) in 2021 were lower compared to those sampled in 2020 but were not meaningfully different to samples retrieved from women sampled in 2018 and 2019.
  • RSV antibody neutralization capacities were reduced by 12 times in women sampled in 2021 compared to women sampled in 2020, and significantly lower than those from 2018 and 2019.
  • Notably, RSV-specific T cell responses did not differ significantly between 2020 and 2021 in women of childbearing age.

The authors postulate that the decline in RSV antibodies and their reduced ability to neutralize the virus may be due to a combination of the natural waning of immunity over time and the absence of exposure to the virus due to pandemic-related mitigation measures such as school and daycare closures, physical distancing, and mask-wearing. They go on to suggest that ongoing viral exposure may be necessary to maintain immunity to RSV.

Blood samples were collected from women of childbearing age in the first year of the pandemic (February to May 2020) and again in its second year (May to June 2021). Samples were also collected between July and August from infants born after March 31, 2019 (for 2020 samples) and between April and June from infants born after March 31, 2020 (for 2021 samples).