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A health worker prepares a dose of a COVID-19 vaccine at a clinic in Richmond, B.C., on April 10, 2021.JONATHAN HAYWARD/The Canadian Press

COVID-19 vaccination has, without a doubt, saved lives – likely millions of them. But, as with all drugs, more is not necessarily better – and that’s why we shouldn’t be rushing to offer fourth doses to the general population.

The evidence simply isn’t there to justify most people getting a “second booster.” At least not in the current circumstances, where there are a lot of infections but hospitalizations are still quite manageable.

Instead, what we should be doing is redoubling our efforts to ensure everyone gets three COVID-19 shots.

There’s solid evidence that a three-dose vaccine regime greatly reduces the risk of hospitalization and death. Ultimately, that’s what matters.

Three seems to be the sweet spot (except for those with compromised immune systems, such as the frail elderly, and people with cancer, transplants and chronic conditions). Yet, to date, less than 48 per cent of eligible Canadians have received three shots. That’s not nearly good enough.

Given the diminishing benefits of additional shots and the growing reluctance, indifference and hesitancy about vaccines, public health officials also need to do some serious rethinking about strategy.

Simply “reboosting” people every six months or so is not a viable approach, practically or economically speaking.

So we have to use other measures – including masking, ventilation, crowd limits and so on – more smartly. That should be the case until we have better vaccines: ones adapted to specific variants or, better yet, a universal coronavirus vaccine.

Good communication has been, and always will be, the number one tool in the public-health tool box. But the messaging coming from public health and politicians is increasingly unhelpful. For the most part, people now have to figure things out on their own.

The recommendations on the need for fourth doses, for example, are all over the map.

In the U.S., a fourth dose is being recommended to anyone over the age of 50, and for anyone over the age of 12 who is immunocompromised, though uptake so far has been laughable.

In Europe, the fourth shot is recommended only for those older than 80 and the severely immunocompromised. “There is no clear evidence, at the moment, that vaccine protection against severe disease is waning substantially in adults between 60 and 79 years of age with a normal immune system, to support the need of a fourth dose,” said Andrea Ammon, director of the European Centre for Disease Prevention and Control.

In most Canadian provinces and territories, meanwhile, the fourth shot is available to those age 60 and over, but jurisdictions have provided little justification for these policies.

Canada’s National Advisory Committee on Immunization (NACI) – which has had some challenges with communication in the past – actually has published a detailed set of recommendations on second boosters. It recommends that, for the time being, these doses should be “rapidly deployed” to Canadians who are older than 80, especially if they live in congregate settings such as long-term care. (Most provinces have already begun to do so.) NACI says provinces should also consider boosting those aged 70 to 79, and high-risk individuals such as those in or from First Nations, Métis and Inuit communities.

Just as importantly though, the NACI says the situation may change if there is a surge or a new variant in the fall, and it reiterates the importance of third doses.

The enthusiasm for fourth doses comes from a study in Israel that showed people over the age of 60 who received four doses were 78 per cent less likely to die than those with three. But that research should be interpreted cautiously because the participants were all volunteers – people who are far more likely to be cautious. Also, it appears that their bolstered immunity for the fourth shot waned quickly. Other studies showed little additional benefit from a fourth dose for healthy individuals.

COVID-19 vaccination does not seem to prevent transmission as much as was hoped, especially with the new variants. But it does markedly reduce the risk of severe illness, especially with three-shot protection. And waiting longer between doses (or after infection) seems to bolster effectiveness, which is another reason to go slow.

Getting shots still matters – maybe more than ever, the way other public-health rules are dropping. But timing matters, too.

Unless you are at high risk of COVID-19 infection, and at least five to six months out from your third shot, there should not be a rush to get number four.

We should tread carefully before considering a mass rollout of fourth doses – and in the meantime, we should do a much better job of promoting what we know does work: three doses for all, and careful targeting for dose four.

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