4th wave of Covid: what explains the rise in cases in Brazil

Brazil is now facing what experts consider the fourth wave of Covid.

In just over a month, the country recorded a 78.3% increase in new cases. As of April 26, the data showed a moving average of 14,600 new diagnoses over the past seven days. As of May 31, the number jumped to 26,032.

“We’ve been observing this process since mid-April, but at a faster pace now. It’s the beginning of a fourth wave, but fortunately it still doesn’t compare to what Brazil has already gone through”, says Fernando Spilki, virologist and coordinator of the Corona-Virus Network. Omica of the MCTI (Ministry of Science, Technology and Innovation), which monitors and sequences the genome of the virus circulating in the country.

The presence of variants with high transmissibility, the relaxation of preventive measures and the reduction of immunity against Covid-19 months after vaccination are factors that explain the increase in cases. At the same time, with advanced vaccination, cases do not have the same severity as previous waves.

The most recent epidemiological bulletin from Fiocruz (Fundação Oswaldo Cruz), released on Thursday (26), points out that almost half of SARS (Severe Acute Respiratory Syndrome) records were due to covid-19 in the period between May 15 and 21. .

According to data from Conass (National Council of Health Secretaries), more than 40,000 Brazilians were diagnosed with Covid-19 in the last 24 hours. The number, however, could be much higher, according to experts.

“We are facing the fourth wave with an unprecedented process. We have never had such poor quality of data in terms of the number of registered cases. Very little is tested and recorded. In addition, with the possibility of self-testing, to avoid bureaucracy, many end up not registering. We have never sailed so in the dark”, points out Spilki.

What explains the increase in cases?

In Spilki’s assessment, there are different factors involved. Among them is the lack of initiative — both public and individual — to try to prevent infections. “Many people stopped wearing a mask, including indoors, so we were exposed to an increase in cases.”

Doctor Vera Rufeisen, an infectious disease specialist at Vera Cruz Hospital, also recalls that the protection rate of vaccines drops a few months after immunization. However, immunizations against Covid-19 continue to work for what they were developed for: preventing more serious cases of the disease, which cause hospitalization and death.

“In addition, we do not have complete immunity against all variants, and due to the change of season, people, already tired of wearing a mask, tend to be more confined, in closed environments.”

Another point, extensively studied by Spilki is the presence of variants with high transmissibility in the Brazilian territory, such as the ômicron.

“Omicron variants, such as BA.2, associated with waves in Europe, are circulating in some places, as well as BA.2.12.1, which is not completely spread across the national territory, but can already be found in some niches and is also responsible for a wave outside the country, in the USA. Apart from these, we also have recombinants such as ‘XQ’, a mixture of the BA.1.1 AND BA.2 variant”, explains Spilki.

These variants, according to the expert, raise concerns about the ability to spread. “They facilitate the path for a process of greater transmission. We do not expect ‘rain of deaths’, as happened before, but be warned.”

Why are there less serious cases today?

Despite the strong rise in new cases, the moving average of deaths has not exceeded 200 deaths per week, according to CONASS data — a number significantly lower than the rates observed before the availability of immunizations.

“In this context, luckily we have vaccination. Not so much in terms of transmission, which is something that the vaccine does not prevent, but for serious cases and deaths — something that the immunizer is able to prevent very well”, says Spilki.

There are no recent studies that analyze the profile of patients who have died from Covid-19 in recent months, but research carried out in different parts of the world shows that those who received the full immunization schedule are 20 times less likely to die from the disease.

That is why the Bulletin of the Fiocruz Covid-19 Observatory points out the stagnation in the growth of vaccine coverage in the adult population as worrying, in addition to the deceleration of the third dose coverage curve, especially due to the substantially lower adherence of adults to the application of the booster dose. .

“Vaccines and the relief of the health system have contributed to the reduction of lethality in Brazil and in several other countries that have achieved high vaccination coverage. It is important to recognize, therefore, that the expansion of vaccination, especially prioritizing regions with low coverage and of reinforcement in more vulnerable population groups, can further reduce the impacts of the pandemic on mortality and hospitalizations”, says the document.

Spilki argues that now “we have to deal with the pandemic with the tools available”.

“It’s time to define strategies to combat what the immunizer cannot check, that is, reduce transmission. Nobody in Brazil talks about major lockdowns, canceling events or activities, but we would need to rethink whether the measure of removing masks was correct We know that prolonged exposure from one individual to another is the main form of transmission, so why not wear masks?”, he says.

The infectious disease specialist at Vera Cruz Hospital reinforces that, no matter how tired people are, it is important to maintain precautionary measures.

“What we should ask is that people go back to avoiding agglomerations, not getting close to people and always wearing masks in closed environments. If they have any respiratory symptoms, if they are absent from work, test and stay isolated so that we can interrupt the chain of transmission of the virus”, recommends Vera Rufeisen.