Objectives: The aim of this study was to assess the spread of denialist messages regarding COVID19 in Brazil, specifically examining how social inequalities contributed to the misconception of chloroquine having a protective effect against the virus. Study design: Three countrywide population-based studies were conducted in 2020 (May 14-21, June 4-7, and June 21-24), including 133 Brazilian cities (n=88,772). Methods: Participants were asked whether they believed in chloroquine protective effect against infection with the SARSCoV 2 virus (no/yes/do not know). A jeopardy index score to assess cumulative social deprivation was calculated based on gender, racial and socioeconomic variables. Descriptive analysis and inequality measures (Slope Index of Inequality, SII; and Concentration Index, CIX) were used to evaluate the main association under investigation. Multinomial logistic regression was used to evaluate 3 category outcome according to independent variables. Results: Overall, 47.9% of participants either believed that chloroquine prevented against COVID-19 or said, I do not know. Misbelief and lack of knowledge about chloroquine were greater among the most vulnerable (lowest levels of education and socioeconomic status). Absolute and relative inequalities were observed according to jeopardy index. Lack of knowledge was 2.49 greater among women than among men. Race/ethnicity minorities, those with low education and low socioeconomic status were more likely to erroneously believe that chloroquine prevented against COVID19. The highest absolute inequality was observed for the category I do not know (SII = -14.3). Conclusions: Misbelief of chloroquine protective effect against the SARS-CoV-2 virus was high in Brazil. People with greater social vulnerability were more likely to wrongly believe chloroquine prevented against COVID-19.

The authors have declared no competing interest.

The study was funded by the Brazilian Ministry of Health, Instituto Serrapilheira, Brazilian Collective Health Association and JBS Fazer o Bem Faz Bem. The funder has no role in study design, data collection/analysis, interpretation of findings, or manuscript writing.

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This study complied with all ethical precepts and legislation governing research with human beings and was approved by the National Research Ethics Commission (CAAE 30721520.7.1001.5313). All participants signed an informed consent form.

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