Covid growth worries, but it is too early to predict a new wave in the country

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A little more than two years have passed since the pandemic began, the feeling is that the worst of Covid is over – thanks, mainly, to vaccination. The possibility of a new wave, however, still cannot be completely ruled out.

This is because the situation of falling cases and deaths from the coronavirus in the country was broken in the last week, when the moving averages of deaths and cases showed an increase in relation to the previous 14 days – of 26%, in the case of deaths, and of 4% for cases.

The rise, however, is considered reduced and still suffers from the effects of two long holidays in a row, Easter and Tiradentes, when there are known to be lower records of new cases and deaths.

However, some data point to a possible rebound, such as the growth in the positivity rate of tests in the last month by the main diagnostic laboratories in the country — from 4% to 12% — and the increase in hospitalizations in the state of São Paulo.

Experts heard by the report, however, say that it is still too early to talk about a new wave of the coronavirus.

Alexandre Naime, an infectious disease specialist at Unesp in Botucatu and vice president of the Brazilian Society of Infectious Diseases, explains that to know if there is an upward or downward trend, it is necessary to look at the historical series. “We had an increase of about 25% [da média móvel de óbitos] within the last week, but these weekly variations can translate to data damming or random variations. Therefore, it is necessary to see a consolidated trend in at least two to three weeks to define a decision-making “, he says.

The same view is shared by Julio Croda, infectologist at Fiocruz. “The two holidays affected the registration of deaths, and the increase in the moving average of deaths was not accompanied by the same level of cases. “, it says.

For him, even the higher positivity rate has not yet reached the levels observed during the wave of the ômicron, in the second half of December 2021 and January of this year. “When there is an explosion of cases, the positivity rate reaches 40%, 60%. In terms of hospitalizations and cases of Srag [síndrome respiratória aguda grave]for example, the Infogripe bulletin has not yet pointed out this increase”, he says.

According to data from the Infogripe bulletin from Fiocruz’s Covid-19 Observatory, released last Friday (29), in the period from April 10 to 23, the moving average of cases of 14,000 represented a drop of 36% compared to the previous two weeks, while the moving average of deaths, of about 100 per day, is 43% lower than the data from 14 days earlier. No state showed an upward trend in any of the indicators (cases, deaths or hospitalizations due to Srag).

Also according to the bulletin, despite the maintenance of the downward trend in the country, the pandemic is not over yet and the risks remain present.

One of these risks, for scientists, is the emergence of new variants. The detection of omicron lineages in other countries, such as the BA.4 and BA.5 subvariants, has already caused concern among health authorities.

The virologist and scientific researcher at the Todos pela Saúde Institute (ITpS), Anderson Brito, released last Thursday (28) updated data from the sequencing of variants in the country that point to a predominance of the BA.2 lineage of the omicron. If until February 1st this subvariant represented 7 out of 10 (69.3%) sequenced samples, on April 23rd it became 84.3% of the samples.

According to Brito, in the last three weeks there has been an increase in the positivity rate of the tests analyzed by the Dasa laboratory, which serve as a basis for the ITpS, and as the public network has a sampling bias due to underreporting, this increase is likely to be even bigger.

“What we are seeing in Brazil based on data from the private testing network is an increase in the average number of positive tests, and we know that this is accompanied by an increase in cases. This, in addition to the scenario that we have already observed in other countries that face a wave of BA.2, leads us to believe that we may be at the beginning of a new wave”, he says.

However, the researcher points out that the behavior of the subvariant in different countries depends fundamentally on hospital capacity and vaccination coverage, including booster. “In the UK there was a very big wave of BA.2 because of this [baixa cobertura de reforço]. In South Africa, we have the introduction of BA.4 and BA.5 strains without much impact on hospitalization indicators”, he says.

The low booster vaccination coverage, however, together with the withdrawal of protective measures and the increase in crowding situations can cause this increase, albeit small, to lead to a rebound, according to infectologist and professor at Unicamp Raquel Stucchi.

“We still cannot say that the increase is related to parties on both holidays, but certainly the agglomerations, the flexibility of masks and the greater circulation of respiratory viruses add up”, he says.

The researcher reinforces the importance of all those over 18 years of age taking the first booster dose (or third dose) and of the elderly over 60 and immunosuppressed taking the second booster dose (or fourth dose).

“The low adherence to the third and fourth doses is a concern in the sense that these people are more vulnerable to a serious illness. And all those with respiratory symptoms should be tested for Covid and wear the mask for at least ten days from the beginning. symptoms”, he adds.

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