In Brazil, New Study Shows The Poor And Indigenous Suffer The Most From Covid-19

The largest population level study of the prevalence of antibodies against the virus that causes Covid-19 was recently completed in Brazil. Population based information on Covid-19 is crucial to understand the impact of the virus on various segments of the population and to guide evidence-based policy decisions on control measures.

The study estimated that in some cities only one in ten infections with the virus that causes Covid-19 were reported as Covid-19 cases. The low proportion of reported cases demonstrates the need for expanded testing in Brazil. The study also found disparities in individuals most affected by infection with the virus that causes Covid-19. These disparities highlight the importance of making policy decisions based on scientific evidence to protect all groups against the negative impacts of Covid-19.

To determine the percentage of people with antibodies against the virus that causes Covid-19, researchers randomly tested residents of 132 cities in Brazil for these antibodies. If a person has antibodies against the virus that causes Covid-19, it suggests that the person was likely to have been infected with this virus previously. In each city, the goal was to test 250 individuals selected at random. However, the number of people who were in fact tested varied by each city. The study’s findings on antibody prevalence are likely to underestimate the true extent of previous infection because of how quickly antibody levels decrease and become undetectable by an antibody test, especially among the majority of cases who are asymptomatic.

Researchers conducted two surveys two weeks apart, so they could measure the change in antibody prevalence over time. The first survey occurred at the end of May and included 25,025 participants. The second survey occurred at the beginning of June and included 31,165 participants. Randomly selected participants provided two drops of blood that was tested for the presence of antibodies using the WONDFO SARS-CoV-2 point of care antibody test. Participants also completed a survey that asked questions about their demographics, socioeconomic status, and uptake of Covid-19 prevention behaviors. The demographic information included sex, ethnicity, age, and education level. The five groups recognized in the official Brazilian classification of ethnicity are: Branco (white), Pardo (Brown), Preto (Black), Amarelo (East Asian), and Indígena (Indigenous).

There were large disparities in infection rates between the ethnic groups and income levels in Brazil. The prevalence of antibodies against Covid-19 in the second survey was 6.4 percent in Indigenous groups compared to 1.4 percent in the white population. Among the poorest twenty percent of participants, prevalence in the second survey was 3.7 percent compared to 1.7 percent among the wealthiest twenty percent of participants. Members of the Indigenous population were over four times more likely to have antibodies against Covid-19 in their blood compared to white people. This large difference is partially explained by region, number of household members, and wealth. Even after controlling for all these factors, Indigenous people were still over fifty percent more likely to have antibodies against Covid-19 in their blood than their white counterparts.

Prevalence of antibodies against Covid-19 according to ethnicity and economic status

Prevalence of antibodies against Covid-19

Ethnicity                    Survey 1         Survey 2

Branco (white)             0.7%              1.4%

Pardo (Brown)             2.4%              3.6%

Preto (Black)              1.2%              3.4%

Amarelo (East Asian)  1.3%              2.1%

Indígena (Indigenous) 4.2%              6.4%

Wealth Quintiles                   

Poorest           2.1%    3.7%

2nd                 1.8%    3.4%

3rd                  1.5%    2.5%

4th                  1.5%    2.5%

Wealthiest    1.0%    1.7%

The Pardo population, those with mixed European, Black, and Indígena ancestry, had the second highest prevalence of Covid-19 antibodies at 2.4 percent in the first survey and 3.6 percent in the second. In both surveys, participants living with many household members were more likely to have antibodies against Covid-19 than those who lived with fewer people.

The most surprising finding to researchers was the geographical concentration of cities with the highest antibody prevalence. Six of the cities with the highest antibody prevalence were found along one 2000 kilometer stretch of the Amazon river. Covid-19 first appeared in the north region of Brazil in the city of Manaus in March. The virus then spread along the main river-boat routes on the Amazon. River boat trips there are often long and overcrowded, providing an optimal vehicle for transmission of the virus. One study found that as the number of boats leaving Manaus to a given city increased, the number of days until the first case was reported in that same city decreased.

Map From Supplementary Material

Between the two studies, an increase in antibody prevalence occurred in most cities. In Boa Vista, a city in Northern Brazil, the prevalence increased from 4.7 percent in the first survey to 25.4 percent in the second. One city, Breves, was a notable exception and was the location of a decrease in antibody prevalence. The city had an antibody prevalence of 25.4 percent in the first survey and a prevalence of 12.2 percent in the second. This could be explained by rapidly decreasing antibody levels after infection with Covid-19, especially among individuals who do not show symptoms. This study found that only one in ten infections were reported as Covid-19 cases in these 133 sentinel cities. This could even be an underestimate of the number of people previously infected with Covid-19 due to the quickly decreasing antibody levels that may not be detected by the test.

Brazil’s response to Covid-19, much like the response in the United States, has been marked by a lack of leadership and a refusal to follow scientific evidence. The President of Brazil, Jair Bolsonaro, opposes social distancing measures and has promoted the use of hydroxychloroquine, despite no evidence that it is an effective treatment for Covid-19. Much like U.S. President Trump, President Bolsonaro of Brazil did not change his handling of the pandemic even after he was infected with the virus in July. Upon testing positive, President Bolsonaro released a video showing him taking hydroxychloroquine. Testing in Brazil is restricted to the most severe cases of Covid-19. Even with over 150,000 deaths as of October 11, 2020, there is evidence that this is an undercount.

Since the beginning of the pandemic, there has been a high rate of turnover of health ministers. Dr. Luiz Mandetta was fired in April due to a disagreement with President Bolsonaro over social distancing measures. Dr. Nelson Teich who replaced Dr. Mandetta quit in May following disagreements with the President over social distancing and the use of hydroxychloroquine. General Eduardo Pazuello, who has no training in public health, served as interim Health Minister from May to September. He became Minister of Health in the middle of October and has recently tested positive for coronavirus.

Due to this lack of leadership from the President and at the Federal level, state governors and other local leaders have had to implement restrictions such as the closure of schools and nonessential businesses and have been the ones to recommend the use of face masks. To ensure that Covid-19 does not continue to impact marginalized groups and those with fewer resources disproportionately, the Federal Government in Brazil must follow scientific evidence and implement Covid-19 mitigation measures such as widespread testing, contact tracing, physical distancing, and the use of face masks.


Read the article on Forbes.

Originally published on October 27, 2020. 

© William A. Haseltine, PhD. All Rights Reserved.