Opinion – Atila Iamarino: How many times can I get Covid?

Unfortunately, this answer will depend much more on your behavior than your immunity.

As I wrote at the beginning of May: “in the absence of measures such as masks, reduction of agglomerations and changes in the ventilation of closed environments, the barrier against the virus that maintains this stability is only our immunity. And […] the situation may be about to change”.

The reason for this statement in May was the detection in South Africa of new versions of the omicron variant capable of reinfecting those who had omicron in January. There, cases of people who are already in the second, third or fourth recent infection with the virus are common.

And here we are, in the midst of another wave of Covid caused by these strains in Brazil, with a lot of people catching Covid again. You probably know several people who have or have had Covid recently, if you haven’t either.

Everything indicates that this reinfection should continue to happen. We have a gradient between infections we only get once in a lifetime and infections we can get multiple times.

At one end are viruses such as measles or the smallpox virus, against which our antibodies and cellular immunity are sufficient to neutralize the pathogen for decades or even a lifetime.

At the other extreme are viruses like HIV, which can change so fast that, without treatment, our immune system is always lagging behind and chasing the wrong lineage.

Among the coronaviruses that infect humans, the Sars-CoV-1, which causes the Sars outbreak, seems to arouse an intermediate immunity. Those who had SARS between 2002 and 2003 still had antibodies capable of neutralizing the virus for at least a year or two afterwards. Among human coronaviruses that cause colds, such as NL63 and OC43, protective immunity appears to last less.

The Sars-CoV-2, which causes Covid, transitioned from the first to the second situation. Immunity against the original Wuhan strain appeared to last for at least six months, and cases of reinfection were rare. But as it continued to circulate and evolve, it acquired mutations that help it evade our immunity. Now, cases of reinfection are so recurrent and so close in time, that it is difficult to know if the person caught Covid again or if they still have the same virus.

Omicron, the first variant that continues to predominate in more than one wave, arouses a smaller immune response than the previous ones and still manages to evade the immune response we already have. And this trend seems to be more pronounced among those who caught Covid before getting vaccinated. Neither vaccines, nor previous infections, nor the infection itself are enough to stop the virus.

To answer the question I asked here two years ago, immunity against Covid is not protective. We have no prospect of collective immunity. We don’t know how many times in a row someone can get the disease and the effects of repeated infections on someone – good ones certainly aren’t, but we don’t know how bad they can be.

Which brings us to a reversal of what I wrote in May. In the absence of the immune barrier, there will be measures such as masks, reduction of agglomerations and changes in ventilation that will prevent you from having Covid again. And the booster dose is an excellent way to prevent the Covid you get from being serious.

The most recent estimate is that more than 1 million lives were saved in Brazil thanks to vaccination against Covid, in 2021 alone. It is urgent that we can extend this protection to children under five years old.