This article was originally published in the Montreal Gazette
I have recently been hearing a lot of people claim that the vaccines don’t work. Of course, when you see large numbers of vaccinated people in the hospital it is easy to lose heart. But as I explained in my last column, when you interpret the numbers correctly, the vaccines offer good protection against hospitalization.
Still, some people contend that the vaccines do not protect against infection, again citing the large number of vaccinated people who get sick. But the real question is whether you are less likely to get sick if vaccinated.
A recent analysis in JAMA demonstrates that you are. Researchers looked at data from more than 70,000 COVID-19 tests done in December in the U.S. to see whether vaccinated people were more likely to test positive. This type of analysis, called a test-negative study, is a bit different from prior studies people have heard about it. The original studies to approve the various COVID-19 vaccines relied on people showing up for tests if they felt symptoms. While there is nothing inherently wrong with this approach, there is the obvious problem that people might not get a COVID test for a variety of reasons. In a test-negative study, a type of case-control study, you begin with everyone who got a COVID-19 test and separate out those who test positive and those who test negative. This type of study has the advantage of minimizing differences between cases and controls in order to get a more accurate measure of vaccine effectiveness. The fact it was done in December also allowed researchers to determine the impact of a third dose against both the Delta and Omicron variants.
Against the Delta variant, getting three doses of any mRNA vaccine (as compared to only two doses) reduced the odds of infection by 84 per cent. The vaccines did less well against Omicron and reduced the odds of infection by 76 per cent. Immunity seemed to wane slightly nine months after the last dose but remained high.
Contrarians will say that this study (and many others like it) only demonstrates a benefit to symptomatic infection and not asymptomatic spread. However, prior research where health care workers were swabbed weekly for COVID-19 demonstrates that vaccination prevents asymptomatic spread as well.
The vaccines are clearly beneficial and protect their users, albeit imperfectly, against COVID-19. However, it is equally clear that with each new variant that efficacy decreases and doing nothing to prevent the emergence of new variants will serve us poorly in the long term. Getting vaccine doses to countries where access is limited is likely our best strategy for preventing a new disruptive variant from sweeping the globe. It is not by accident that new variants emerge from countries with low vaccination rates and uncontrolled spread of COVID-19.
But we are not doing particularly well in that regard. Of the 200 million doses Canada has pledged to COVAX for international distribution, we have supplied just under 12 million. What’s worse, many doses sent to countries like Nigeria were set to expire and were therefore essentially useless and went unused. Of course, the solution is not just delivering doses. Countries also need the support and resources to distribute vaccines. Addressing patent issues to allow countries to make their own doses would also help. But the central issue is that in North America, 76 per cent of the population has received at least one vaccine dose whereas in Africa it is only 14 per cent. Rectifying that imbalance is critical. It is likely the only practical avenue we have for reducing the probability of the emergency of a new variant. It serves our own self-interest to help vaccinate the rest of the planet. It is also the morally correct thing to do.
