Do you really need a fourth COVID-19 shot? Here’s what the federal advisory committee says

Canada should get ready to rapidly deploy fourth doses of COVID vaccine in the coming weeks as protection against the virus continues to wane, particularly for those 80 and older, the national body responsible for vaccination advice said Tuesday.

For many who have rolled up their sleeves for a first, second and even third, the news has been met with some confusion. What happened to vaccination being just two shots?

While fourth doses have become common in some other countries and an option already in some provinces, the missive from the National Advisory Committee on Immunization, known as NACI, is the first cohesive Canadian guidance on the practice. It comes at a time, NACI says, when protection from vaccines is wavering, restrictions are lifting and the future of the pandemic is anything but certain.

Generally speaking, the virus is continuing to circulate, and the very spreadable Omicron subvariant known as BA. 2 is now dominant. Meanwhile, public health measures such as masking are dropping in many parts of the country.

But at a time when 85 per cent of the population has two shots of vaccine - though we're lagging a bit on third shots - the challenge presented is different than it was two years ago.

Data from around the world has shown that the vaccines' protection against infection decreases over time - a phenomenon that is not unusual for vaccines, but which has made people particularly vulnerable to these new, more easily spreading variants.

Wealthy countries with access to strong vaccine supply, like Canada, have begun grappling with how to use additional doses to top up flagging defences against Omicron, particularly for those most vulnerable.

It's worth noting that the vaccines still offer decent protection for most people against severe illness, a task separate from stopping infection. Vaccinated people are still far less likely to get seriously ill should they get sick.

While Omicron cases in general are less severe than previous variants, more vulnerable people are more likely to be hit with a serious case of COVID, should they be reinfected. That's why NACI is pushing for certain groups to be prioritized with fourth doses: seniors living in group settings and those over 80 living in the community.

We know that vaccination provides excellent protection against illness," Dr. Tara Kiran, a family doctor at St. Michael's Hospital, told the Star before the new recommendations were released.

There's no question it lowers your risk and it lowers the risk of you spreading it to other people. It's also clear, though, that your immunity wanes over time, and how much you get in the first place and how long it takes to wane does depends on your age."

(Although the matter is particularly urgent for those over 80, NACI also says jurisdictions might offer a second booster dose to all adults over 70 living in the community, or to adults younger then 70 in or from First Nation, Metis or Inuit communities.)

Ideally, the fourth dose would be provided six months after the last.

There remains considerable uncertainty regarding the long-term evolution of the COVID-19 pandemic," the recommendations note, adding that it's not yet known how serious future waves could be, particularly because of the potential for new variants.

Right now, it's not necessary for the general population to get a second booster because the core goal here is to prevent severe disease, NACI vice-chair Dr. Robyn Harrison says in the report.

However, future planning should take into account that additional boosters may be required in the fall of 2022 or earlier in other groups if close monitoring suggests more concerning trends in the COVID-19 pandemic," Harrison says.

For now, it's important that those at highest risk be protected first, NACI says. In any case, COVID cases will increase" come fall, it adds.

Here in Canada, a fourth shot usually means either Moderna or Pfizer, the two mRNA options that have been authorized as booster shots and which have been shown to be most powerful against the new variants. But NACI says that Novavax, a recently authorized protein-based vaccine, is also an option for those either unable or unwilling to take one of the mRNAs.

According to NACI, preliminary data suggests fourth doses are as safe as those that came before.

It's not clear yet what uptake on fourth shots here will be, particularly as Canada falls behind on third doses, when compared to other nations with plentiful supplies of vaccine. Just under half of all Canadians - more than 18 million people - have gotten a third dose so far.

(Over a year into an intensive vaccination campaign, the math is getting murky, as NACI concedes. The basic initial COVID vaccination for most people is two doses, though for those who are immunocompromised, three shots is now what's regarded as full vaccination. What NACI is talking about now is what they call the booster after the first booster, so that means a fourth shot or a fifth, depending on how many you got originally.)

Using vaccines for second boosters is not something that is currently authorized by Health Canada, so doing so would be considered off label," the term for when doctors use a medication for something it is not specifically recommended for. The final decision about how to use vaccines are made by the provinces, several of which have already taken the plunge.

Shortly after the NACI recommendations were made public, British Columbia announced it would offer fourth doses to people over 70 and residents of long-term care and will consider it for Indigenous adults over 55. Ontario has begun offering them to those over 60, while Alberta has already been offering them to any immunocompromised adult.

The practice is already well underway in some other countries.

Back in January, Israel was the first country to recommend a fourth dose for all adults, while the American FDA just last week authorized it for those who are immunocompromised or older than 50.

Alex Boyd is a Calgary-based reporter for the Star. Follow her on Twitter: @alex_n_boyd