Reasons for why cases of covid-19 have grown again in Brazil

The curve of new confirmed cases of coronavirus in Brazil reversed the downward trend, and since last week, it has risen again.
Data from the Health Intelligence Laboratory (LIS) of the Faculty of Medicine of the University of São Paulo (USP), in Ribeirão Preto, compiled from statistics from the Ministry of Health and based on the average of the seven days immediately preceding, reveal that the number of confirmed cases of covid-19 is on an upward trajectory — and "should continue like this," says Domingos Alves, coordinator of lis.
This method, which takes into account the average of the previous seven days, is used to correct possible distortions in the accounting of numbers.
A survey by Reuters news agency reinforces this upward trend.
Nearly 40 countries, including Brazil, recorded daily records for coronavirus infections last week, double the previous week, according to Reuters.
Last Friday (24/07), according to the World Health Organization (WHO), the world recorded 284,196 new cases in a single day, a record.
The discharge was pulled by the United States and Brazil, which accounted for almost half of the new infections. The previous mark was 259,848 on July 18.
Worldwide, there are already more than 15.7 million confirmed cases of covid-19 and 640,000 deaths.
The number of cases has been increasing not only in countries such as the United States, Brazil and India, but in Australia, Japan, Hong Kong, Bolivia, Sudan, Ethiopia, Bulgaria, Belgium, Uzbekistan and Israel, among others.
In Brazil, the number of new infections per day peaked at 45,665 last Saturday, considering the average of the previous seven days. In the previous week, this number was approximately 30% lower, 33,573.
Three main points have drawn the attention of experts:
1) Interiorization
Some states where the capitals registered a reduction in the number of cases began to see an increase in the number of cases inside.
This is the case of São Paulo, Rio de Janeiro and Ceará, for example.
"The worsening of this internalization can be seen around July 20 in these three states," alves says.
Alves points out that the moving average of deaths in these federation units has remained "high" in recent weeks.
He says he believes that the cases of the interior should begin "to supplant those of the capital". This effect, according to Alves, also has the potential to re-affect capital in the medium term.
"We call it the boomerang effect. Furthermore, the decreases in the number of cases in the capitals of these States are not stable."
Alves argues that there is still no talk of "herd immunity" (also called "group immunity" or "collective immunity").
It occurs when a sufficiently large part of a population is immune (protected) against this disease and contributes to it not spreading. As there is not yet a vaccine against covid-19, this herd immunity would only be achieved by a "natural" immunity developed by an important part of the population after being infected.
But many experts warn that herd immunity would not be the best strategy to beat coronavirus.
In addition, there are still many doubts about the immunity we have developed against this disease. A recent study from King's College London in the UK showed that patients recovering from covid-19 possibly lose immunity within months.
"What happened was a phenomenon known as 'protective bubbles'. These bubbles may burst in the coming weeks due to the relaxation of social isolation measures with the reopening, and we may begin to see a worsening of the situation," he adds.
A recent study conducted by researchers of the Covid-19 Action initiative, dedicated to studying the evolution of the disease, showed that the rate of slowdown in the number of coronavirus cases would be related to the formation of "protective bubbles" in cities such as São Paulo.
"Protective bubbles were formed in the city of São Paulo, where groups with many infected and groups almost without infections do not interact. This explains why the pace of the disease slowed down in the city without reaching community immunity. We also show that an eventual increase in circulation may burst these bubbles," the study authors say.
2) Increase in cases in the South and Midwest
In recent weeks, there has been a significant increase in new cases of coronavirus in the South and Midwest, until then regions that had managed to control the contagion of the disease.
In Santa Catarina, for example, the moving average of new cases reached 3274 on July 28, a 254% increase compared to July 1.
The same happened in Paraná and Rio Grande Sul.
In the Midwest region, Goiás has been recording a strong increase in the number of new cases since july 21st.
3) Increase in cases in Minas Gerais
The state had been controlling the contagion of the disease, but, as of June, it has recorded an increase in the number of cases and deaths.
It took, for example, only twenty days for Minas Gerais to double the mark of a thousand deaths by the new coronavirus.
Although the average death per 100,000 inhabitants is lower than its southeast neighbors, the state found, in the first 20 days of July, an average of 52 deaths per day and 2,339 new cases.
According to Alves, in Belo Horizonte, which until then had been successful in controlling the pandemic, the number of cases increased — and the occupancy rate of ICUs (Intensive Care Units) rose again, reaching 92%, a level similar to the beginning of this month.
Uberlândia, the second most populous city in the state, with almost 700,000 inhabitants, is one of the epicenters of the pandemic in the state.
About 90% of the 853 municipalities of Minas Gerais have reported cases of coronavirus.
Despite the increases in the number of cases, Alves says he believes there is no second wave.
"What we have seen is still a consequence of the first wave. The curves of Brazil and the countries that carried out mass confinement of their population or even remained open-door, as is the case in Sweden, are not comparable", he said.
"What has happened in Brazil is much more similar to what happens in the United States," he concludes.