By Pedro Curi Hallal
Studies must continue to fully understand history
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Since the beginning of the Covid-19 pandemic in Brazil, we epidemiologists have spoken to the importance of field research to understand the behavior of the virus in the country. We were at least partially heard. Epicovid19-BR – the largest Brazilian study of the coronavirus – was coordinated by the Center for Epidemiological Research at Pelotas Federal University and has already tested more than 120,000 people in all states to find out the actual number of people infected. But the quest for a better understanding of the epidemic shouldn’t stop there.
At this moment, given the attention of the media, managers and researchers themselves, who have focused on the much-dreamed and necessary vaccination of the population, we cannot forget that epidemiological research does not end with the vaccine. On the contrary: knowing the percentage of people with antibodies to the coronavirus among vaccinated and non-vaccinated people will be one of the most important scientific research questions in Brazil in 2021.
While in 2020, at the height of the pandemic, people who had antibodies were necessarily infected with the virus, in 2021 we will have people with antibodies made by the contamination and others with antibodies made by vaccination were. In the real world, this will be a test of vaccine effectiveness.
In the case of Epicovid19-BR, there were four phases of data collection that took place in the months of May, June and August. A fifth phase will take place in early 2021. In Rio Grande do Sul, Epicovid19-RS has already tested more than 35,000 gauchos across the state in eight phases of data collection: the first in April, less than 20 days after the state’s first death was recorded. Similar studies, inspired by Epicovid19, have been conducted in several cities and states in Brazil, including São Luís (MA), São Paulo (SP), Ribeirão Preto (SP), and Espírito Santo.
In the first three phases, Epicovid19-BR taught us that if we want to know the actual number of Brazilians already infected with the coronavirus, we should multiply the number in the official statistics by six. Epidemiological studies have also shown that children are at the same risk of infection as adults.
These studies also revealed profound socio-economic, ethno-racial, and regional differences in the spread of the coronavirus in Brazil. While the proportion of infected people in the north was almost 10% in May, it was no more than 1% in the other regions of Brazil. At different stages of the research, indigenous peoples were at much higher risk of exposure to the virus than other ethnic groups. In addition, at all stages of Epicovid19-BR, the poorest 20% of the population had twice the risk of infection than the richest 20% of the population.
Epicovid19-BR also proved that the claim that the majority of people infected with the coronavirus would not have any symptoms of the disease was false. In fact, only 17% of those infected do not develop symptoms, according to a recent review of world literature.
Many of the hypotheses made at the start of the pandemic fell apart as soon as we began to examine them empirically. Continuing this type of population studies after we enter the immunization phase is important to fully understand the story. This knowledge will support the most effective public policy for this and future epidemics.
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Pedro Curi Hallal is an epidemiologist, dean of the Federal University of Pelotas and coordinator of Epicovid19.
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