Emerging evidence on COVID-19 boosters among care home population

Andrew P. Costa, Department of Health Research Methods Evidence, and Impact McMaster University Hamilton, Canada

The “COVID-19 in Long-term Care Study” (https://covidinltc.ca/ ) is an immunity surveillance study to inform practice and immunization policy for seniors in nursing homes and assisted living facilities (also known as retirement homes) in Ontario, Canada.

In a recent pre-print (https://www.medrxiv.org/content/10.1101/2021.12.17.21267996v1) that strongly supports 3rd dose/booster mRNA vaccines in nursing homes, we found that:

  • Residents mount a robust antibody response to a 3rd mRNA vaccination, with greater neutralization capacity compared to a 2-dose series for both wild type and beta variants.
  • The immunity benefits of a 3rd dose is particularly large compared to residents who are over 4 months from their 2nd dose.
  • Neutralization performance for the beta variant (most immunological similar to omicron) is reduced, which provides context to estimate (though may not accurately mimic) performance for the omicron variant.
  • Nursing home and retirement home / assisted living residents have a very similar immune (humoral) profile, suggesting that vaccine policies should be the same across settings.

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