when the Covid-19 emerged as an entirely new disease, many wondered if the infection caused by the coronavirus would be the type where symptoms only appear once, such as chickenpox (varicella), for example. The response did not take long and in the first year of the pandemic, the first cases of reinfection with clinical pictures began to appear, even if in rare events.
Although contagion promotes the body’s natural defense, ensuring protection against the virus for a period of time, reinfections became increasingly common as new variants of Sars-Cov-2 appeared, even with the expansion of vaccination coverage among the population, including booster doses. So what explains this?
It is important to point out that vaccines are proven to be effective in significantly reducing severe cases and deaths from the diseasebut none is able to completely avoid infection by the virus, which does not cancel out the protection given by them and keeps them as the main ally in the fight against the pandemic.
Geneticist Renan Pedra, a professor at UFMG (Federal University of Minas Gerais), explains that the entry of the virus into the body cannot be preventedwhich is true for any pathogen of this type.
“Even in the case of chickenpox, a person can have other contacts with the virus throughout life, but not have the clinical manifestation of the disease, because they have a level of defense great enough or efficient to neutralize that virus before it can generate the clinical characteristic that is expected of it”, he says.
In this sense, it is possible to say that the ability of the coronavirus to generate new infections capable of leading to Covid-19 is not uncommon. What is new in this case is that O Sars-Cov-2 has caused new reinfections in shorter and shorter time spansaccording to the geneticist.
“In early January, when the wave caused by Ômicron reached its peak, we started to discuss reinfection, but since most were people who had been infected by Gamma, eventually eight months or even a year earlier, it was a reinfection that somehow This way was already expected and it was even the reason to imagine the need for other doses of the vaccine, because we knew that this immunity mounted, either by the vaccine or by natural infection, was not for life”, says the specialist.
The Ômicron and its variations, considered more transmissible than the previous strains, lead the main hypotheses about the increase in the frequency with which reinfections have occurred, according to infectologist João Prats, from BP – A Beneficência Portuguesa de São Paulo.
“Ômicron was the champion of reinfections with mild cases, because it had an important change in the proteins [do vírus], and the vaccine protection interval decreased. A lot of people came to the office and asked why they had Covid again. It’s a combination of things: the duration of protection is shorter than we expected [das vacinas e da infecção natural]the emergence of new variants, especially Ômicron, and the time it took to revaccinate [dose de reforço]”, explains the doctor.
Recently, the Ministry of Health started to recommend the fourth dose of the vaccine against Covid-19 for people over 50 and professionals who work on the front lines of health services.
Although the country is witnessing a progressive increase in hospitalizations for Srag (severe acute respiratory syndrome) caused by the coronavirus – which already correspond to 70% of hospitalizations by the disease – there is still no forecast that this second booster dose will be extended to the general population.
Geneticist Renan Pedra warns that there is an underreporting of the numbers of reinfectionswhich can contribute to the population thinking of the issue as something unusual or that it loosens protection measures after vaccination or natural infection.
“In Brazil, we have great laboratory difficulties in confirming reinfections and with the self-tests it became even more difficult. So, in fact, it’s much more common than we think, there’s absolutely no doubt about it,” he says.
Experts also point out that it is not possible to compare the frequency of Covid-19 cases with that of flu-like syndromes caused by other respiratory viruses.
First, because there is no pattern of incidence of the coronavirus, that is, it is not possible to say that it is seasonal, like influenza, which has an expected peak always in winter.
“We saw that we even spent the summer with a very high number of cases of Covid-19, so we can’t predict anything yet. Perhaps it could be a disease that does not have this seasonality in the year and that, eventually, has a number of cases that may be lower than what we are seeing now, but that are evenly distributed throughout the year”, says the geneticist.
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