It's time for a more nuanced approach to prioritizing COVID-19 vaccinations as more contagious variants become prevalent and a third wave of infections threatens to overwhelm hospitals in some provinces, according to an analysis published today in the Canadian Medical Association Journal.
"The third wave is showing us that the most vulnerable are people in economically marginalized neighbourhoods where people live and work in close proximity--a group that wasn't prioritized for vaccination before."
McAlister and three other authors, including U of A professor of medicine Lynora Saxinger, who co-chairs the scientific advisory group for Alberta Health Services' COVID-19 Emergency Coordination Centre, analyzed data from the Canadian Community Health Survey for 61,000 Canadian adults. They identified how many have conditions that are recognized as risk factors for severe COVID-19 disease, including high blood pressure, obesity, diabetes and smoking.
"At least 75 per cent of Canadian adults have at least one risk factor and one-third have two or more risk factors for severe illness if they contract COVID-19," McAlister said. "When 75 per cent of people are eligible for prioritization, that's not really prioritization."
It was appropriate to give seniors living in communal settings and the very elderly shots first, as they were clearly the most likely to face severe disease and death at the time, McAlister said, but now the focus should also be on neighbourhoods and workplaces facing a higher risk of infection. He applauded the Alberta government's recent announcement that it will open vaccine clinics at the Cargill meat packing plant in High River as an example of the new direction that should be taken.
McAlister also supports the recommendation from the National Advisory Committee on Immunization to give first doses to as many Canadians as possible, even if it means waiting up to three months to administer second doses while vaccine supplies are limited. "The science is evolving rapidly, but there is accumulating evidence showing that after the first shot we are getting about 80 per cent efficacy, at least in the short-term, so it looks like delaying second doses while we try to get more first doses into arms is a reasonable approach if we continue to be faced with vaccine shortages," McAlister said. "Of course, how long that first-dose protection will last, we will only know in retrospect."
He noted that some groups should be given special consideration to get their second dose more quickly. For example, cancer and transplant patients do not develop the same level of immunity from the first dose as others.
"They seem to get only partial immunity, which means they are at a greater risk for infection, giving the virus another chance to mutate into a variant and get passed on," McAlister explained. "We want as many people as possible to develop immunity as quickly as possible so there's less chance for new variants to develop."
He also reiterated that until we know whether vaccines protect against all of the variants of concern and until the Canadian population has reached herd immunity, thought to be around 70 per cent, we will have to continue public health measures such as wearing masks, socially distancing and washing hands often.