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 Tuesday.
"They are also at increased risk for severe disease because of their age and underlying medical conditions."
The rise of the more transmissible delta variant is one reason to offer maximum protection to vulnerable people in congregate-living environments, the recommendation said.
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 rollout, 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."
Potential signs of waning immunity in LTC homes
Dr. Allison McGeer, a medical microbiologist and infectious disease specialist at Mount Sinai Hospital in Toronto, said she welcomes NACI's recommendation because there is data that suggests immunity may be waning among long-term care residents.
McGeer is the lead author of a recent preprint study (meaning it has not yet been peer-reviewed) that found much lower levels of neutralizing antibody response against coronavirus among long-term care residents compared to the staff who cared for them.
It's "probable" that booster shots will help, McGeer told CBC News after NACI's announcement.
Ontario long-term care homes have already started administering boosters, she said, and her group will be studying what happens with that demographic.
"This is our opportunity to make sure that we're doing everything we can [to protect long-term care residents]," McGeer said.
In addition to preventing serious illness and death, the goal of bolstering protection as much as possible is to prevent outbreaks in long-term care homes, which force residents back into isolation and drastically affects their quality of life, she said.
Boosters not yet needed for all seniors, expert says
Dr. Samir Sinha, director of geriatrics at Mount Sinai and University Health Network hospitals in Toronto, also applauded the move to provide booster shots to long-term care residents.
Although he would have liked to see the recommendation come out sooner, NACI was right to make it specific to people living in long-term care or other congregate-living environments, Sinha said, noting it should not yet be extrapolated to apply to all seniors.
At this point, he said, he doesn't see a need for the recent U.S. recommendation — that everyone aged 65 and older should be eligible for a booster shot — to be applied in Canada.
"It's about degrees of risk," Sinha said.
Evidence of waning immunity, together with the risks of congregate living — including contact with health-care workers who may not be vaccinated — and the fact that people who live in long-term care homes are usually there because they have serious health conditions, are all reasons that booster shots are a good idea for seniors living in those settings, he said.
The next group of people who should be approved for booster shots, Sinha said, should be seniors who rely on home care — because they share many of the same risk factors as those living in long-term care, including serious health issues and multiple caregivers coming in and out.
"A lot of community-dwelling older adults are actually relatively healthy. They do not have the [same] degree of risk," Sinha said.
It's important to be "very measured" with decisions about who gets booster shots, he said.
"A third of the world's population hasn't even received a first dose of the vaccine," Sinha said. "The longer that we have other populations that aren't even getting a single dose, it puts the entire global population at risk of new mutations or new variants."
That poses a bigger risk to most people than not getting a booster shot, Sinha said.
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.
ABOUT THE AUTHOR
Nicole Ireland is a CBC News journalist with a special interest in health and social justice stories. Based in Toronto, she has lived and worked in Thunder Bay, Ont.; Iqaluit, Nunavut; and Beirut, Lebanon.
With files from Adam Miller and Lauren Pelley
Credit belongs to : www.cbc.ca