Opinion – Atila Iamarino: Take your booster dose of the Covid vaccine

This Tuesday (16), the Ministry of Health announced that, as of Saturday (20), all Brazilians over 18 will be able to take a third dose of the vaccine against Covid. And whoever took the single dose of Janssen should take a second dose. As I commented in July that we would not need new vaccines and having regularly criticized some of the ministry’s positions here – and letting another 1.2 million tests spoil again doesn’t help –, it would be important to talk about the correctness of this decision. And why it’s important that you take your booster dose.

From July until now, we have faced the delta variant, which is so transmissible that those who have not received or who have not responded so well to the vaccination are found well. And we see a drop in protection among vaccinated seniors in countries that have been vaccinated before, like the UK and Israel. Studies in these countries are showing that a booster dose among the elderly was enough to increase the effectiveness of vaccination to more than 90%. Which should last at least 9 months. Effective enough to have a good impact even on the transmission of the virus. Perhaps this regimen with a third dose months later should be the standard.

What is the ideal dose and timing regimen? Which combination prevents transmission of the virus? We don’t know, this knowledge only comes with practice. In order to have safe and effective vaccines in 2020, their development was focused. As research centers and pharmaceuticals came up with promising candidates, they needed to choose the dose regimen they would test. Optimizing volume to yield more applications and trigger a robust immune response, but not to the point of causing severe inflammatory reactions. And the time frame to expedite the vaccination, but allowing time for the immune system to work.

Once the parameters are chosen, the cost is not worth exploring other options. With the Oxford/AstraZeneca vaccine, it was accidentally discovered that a lower volume starting dose could increase efficacy. Even so, the study in Viana, Espírito Santo, will take all of 2021 to confirm results with half a dose. Perhaps we could have saved millions of doses and millions of dollars, but the time and safety of what had already been tested was a priority. We’re still using two full shots in the meantime.

Now we see in practice how vaccines behave. When the World Health Organization and the US government announced they had funded vaccines, they called for at least 50% effectiveness in protecting against the disease. But as they’ve delivered that and more, what’s expected of vaccines has changed. Rather than continuing with isolation measures, many countries relax the measures and rely on vaccination to stop the virus. But to prevent delta, we need more than 85% of the population on two doses, according to the new wave of cases in European countries. And we might need a booster shot.

Here in Brazil, where closure is even more taboo than vaccination for the federal government, it is imperative that we reach close to 90% of the population with at least two doses. Which involves vaccinating children too. This needs to be the most urgent priority. In the meantime, and perhaps despite this, if you are among those who have already taken both doses, a third booster dose brings protection that can make a world of difference. Even more so here, if what happens in Europe is repeated in Brazil in 2022, as happened in past waves at Covid.