When the doctor Adriel Ramalho Santana had the first symptoms of Covid-19, in March 2020, almost nothing was known about the disease. Santana believes he was infected at work by a colleague who had returned from a trip to Italy, then the global epicenter of the disease. “I took a serological test some time after showing the symptoms, and the result came back positive for coronavirus antibodies”, he says.

Almost a year later, in the last month of February, Santana presented a more intense picture, with fever, headache, cough, loss of smell and taste and shortness of breath. Looked for a hospital. The diagnosis of the coronavirus was confirmed. “Unlike what I heard out there, my reinfection was more symptomatic and had a greater impact,” he says.

Re-infections by Sars-CoV-2 are still a subject of controversy, something to be expected in the face of a disease that emerged recently. According to data from the Ministry of Health, until April 5, 2021, eight Brazilians had confirmed a second diagnosis of Covid-19.

According to the Covid-19 Reinfection Tracker platform of the Dutch news agency BNO News, there are 69 confirmed cases in the world, two resulting in death – a 74-year-old Israeli man and an 89-year-old Dutch woman.

By the numbers presented, these episodes seem to be very rare. But there is certainly underreporting, partially explained by the difficulty of confirming a reinfection with 100% certainty.

First of all, professionals require a minimum interval of 90 days between the first and second infection (which helps to rule out the possibility that the same virus has remained in the body for a long time). In addition, it is necessary to carry out the genetic sequencing of the virus on the two occasions in which it invaded the body. And not just any place does this test: it is estimated that 0.03% of Covid-19 cases pass this assessment in Brazil. In the UK, the rate is approximately 5%.

As if that were not enough, another requirement to determine reinfection is that the patient has two positive results by the RT-PCR exam. “Proving this type of event is very complicated”, admits biologist Camila Romano, from the Institute of Tropical Medicine at the University of São Paulo. “And, in my opinion, underreporting impacts our understanding of the subject”, he adds. According to the researcher, reinfections by the coronavirus can reach up to 15% of cases.

One hypothesis for reinfections is that the person's immune system for some reason has not created adequate barriers against the virus. Or, over time, lost them.

And the different variants that popped up would also play a relevant role in this scenario. From a preliminary Brazilian study, scientists came to estimate that the P1 variant, discovered for the first time in Manaus, would be able to evade the immune system of 25% to 61% of those infected with the “original Sars-CoV-2”.

According to Camila, it is too early to say, based on clinical observation, that the new variants will increase reinfections. “The first cases appeared in December”, he recalls.

It is true that the number of cases of Covid-19 in Brazil has grown dramatically in parallel with the appearance of P1 and P17. But, according to the researcher, it is difficult to know whether infections have risen due to the variants or whether the variants have emerged as a result of the lack of control of the pandemic. Now, it is easier for a mutation to propagate in an environment favorable to contagion. If, on the other hand, it arises within a person who is completely isolated, it certainly will not pass on – yet another reason to maintain physical distance and value vaccination.

Anyway, virologist Felipe Naveca, from Fiocruz Amazônia, says that the constant evolution of the virus can make the work of our immune system difficult. “The emergence of new variants is indicative that we may have more reinfection events in the future”, he says. "As long as we give it a chance, the virus will continue to change."

All this to say that having caught Covid-19 once does not free anyone from the daily care of the pandemic. Nor does it dispense with the need to receive the coronavirus vaccine.

In fact, even after taking your doses, you must maintain the use of masks and other safety measures - at least until a good part of the population is immunized and the authorities relax certain attitudes.

“We are running after a problem that runs after us”, laments Camila.

Adriel, the doctor who believes he has been infected twice, also thinks like this: “Reinfection happens, it is a reality”. Reporting his own experience, he recalls that not necessarily the second occurrence will lead to light frames.

Severity and transmission in cases of reinfection with coronavirus

Naveca closely followed the first three cases of reinfection recorded in the country. He says that the patients evolved well in all of them. “But it doesn't mean that others will be like that”, he warns. As we have shown before, deaths after a second Covid-19 attack have already been reported.

According to experts, the great risk of reinfection is associated with the fact that the person retransmits the virus. Even if she only exhibits mild symptoms, she becomes a spreader of Sars-CoV-2 — just like anyone who has caught it for the first time.

Source: Veja Saúde - https://saude.abril.com.br/medicina/reinfeccao-pelo-coronavirus-qual-o-risco-real/