The short and disappointing answer is that no one really knows yet in large part because this campaign is still too young.
Israel was first off the mark with its plan to provide boosters to everyone in Israel over the age of 50 but that campaign is still only 3 weeks old so clearly it’s way too soon to tell even for Israelis if people who get that added shot are actually significantly less likely to experience breakthrough infections than those higher-risk people who don’t get a booster.
That said, there’s little question now from emerging studies that 1) antibody levels to coronavirus drop with time, and 2) booster doses do increase immediate antibody levels, which should be a good thing.
In fact, based on that latter determination – waning antibody levels after several months – both Germany and France are now recommending boosters in high-risk individuals and the US has recently announced that they will offer 3rd shot boosters to all those with lowered immunity (clearly not always an easy determination to make), and the US gov’t has also leaked info that it’s probably going to recommend boosters for all Americans by early fall.
Canada? Not so much.
In fact, not a word yet.
But before you jump all over the hesitant Canadian health authorities for their standard me-not-first response, you should note that there are several important considerations to take into account in Canada that are hard to extract from Israeli tactics and data.
First, Israel used a very different dosing schedule from Canada, which is why Israel was so far ahead for such a long time in the percentage of the population that had received 2 vaccines.
Israel stuck to the Pfizer recommended dosing regime – 2nd dose to follow first dose 21 days later – which was in fact applied to the vast majority of the high-risk population.
In Canada, however, 2nd doses were given 6, 8, even 12 weeks after the first dose, and there are intriguing studies to show that this may boost effective antibody levels more efficiently – and hence, boost immunity to infection – than the Pfizer recommended schedule.
Also, it’s the Delta variant of the virus that is causing the current havoc but the boosters in use right now are the ones that were produced for the original strain of the virus.
It may be, and we can only hope, that if boosters are needed, we may get a much better immune bounce from a new booster designed specifically for the Delta variant, something both Pfizer and Moderna have developed.
Third, before we jump on the boosters-for-everyone bandwagon, even if the boosters provide some immune protection, we have absolutely no idea yet whether these boosters will be as necessary in say a healthy 30-year-old as they are likely to be in a 75-year-old.
And finally, there’s the unavoidable moral issue: In a world in which at least /4 of the population is still either not immunized at all or only somewhat immunized, is it right for us, who, even with Delta, have some very good protection against severe outcomes to hog the still-limited supply of vaccines for use as boosters?