Canadian seniors living in long-term care homes and other congregate-care settings should get COVID-19 vaccine booster shots, Canada’s vaccine advisory body recommends.
Residents of such sites, including retirement homes and assisted-living facilities “are at increased risk for COVID-19 infection because of their daily interactions with other residents and staff,” said the National Advisory Committee on Immunization (NACI) in updated guidance released online on Tuesday.
“They are also at increased risk for severe disease because of their age and underlying medical conditions.”
The amount of time that has passed since residents received their initial vaccinations is a factor in the recommendation — given that older adults may “have a less durable response to vaccines and/or past infection compared to younger adults.”
“Older Canadians residing in congregate living settings were prioritized for the COVID-19 vaccine when the vaccines were first authorized; therefore, many completed their COVID-19 vaccination series early in the vaccine roll-out, leaving more time for waning should it occur,” NACI said.
Many long-term care residents had their initial COVID-19 shots spaced out over shorter intervals based on the manufacturers’ guidance — 21 days between doses for Pfizer-BioNTech (Comirnaty) and 28 days for Moderna (Spikevax).
Current evidence now suggests that longer intervals between doses result in higher immune responses, NACI said, and therefore the original schedule may have contributed to “more rapid waning of protection, including against variants of concern.”
In its guidance, NACI noted that its booster shot recommendation for residents of long-term care homes is not the same as recommending a third dose as part of the initial vaccination schedule.
“The intent of a booster dose is to restore protection that may have waned over time in individuals who responded adequately to a primary vaccine series,” the advisory committee said.
That’s different than the recommendation NACI issued just over two weeks ago for moderately to severely immunocompromised Canadians. People who are immunocompromised should receive three doses of COVID-19 vaccine as part of the standard immunization schedule, NACI said, because they may not mount an adequate immune response to two doses in the first place.