An analysis of COVID-19 mortality underreporting based on data available from official Brazilian government internet portals (Preprint)

BACKGROUND: In Brazil, expressive numbers of COVID-19 cases and deaths are reported and, comparing with other countries, it has become the second most affected and impacted country (as of June 9th). Official Brazilian government sources present contradictory data on the impact of the disease, thus, there is a high chance that the actual number of infected and deaths in Brazil is far larger than those officially notified, and it is very likely that the actual growth of the disease is being underestimated. OBJECTIVE: This study investigates the underreporting of cases and deaths related to COVID-19 in the most affected Brazilian cities, from public sources available on official Brazilian government internet portals, in order to identify the real scenario of the pandemic in Brazil. METHODS: This research used data from the historical series of deaths, due to respiratory problems and other natural causes, from two public portals: DATASUS (2010 to 2018) and the Brazilian Transparency Portal of Civil Registry (2019 to 2020). These data were used to build time series models (modular regressions) able to predict the expected behavior of deaths in 2020. The forecasts are used to estimate the possible number of death reports that were incorrectly registered during the pandemic and posted on official Brazilian internet portals in the most affected cities in the country. RESULTS: The model found a significant disagreement between the real and expected values. The number of deaths due to SARS was considerably higher in all of the cities, presenting increases between 493% and 5820%. Considering the cities of the case study, an average underreporting of 40.68%, varying between 25.9% and 62.7%, is estimated for deaths related to COVID-19. CONCLUSIONS: The quite significant rates of underreporting of deaths presented in our research allow us to realize that the officially released numbers to be much lower than the actual numbers, making it impossible for the authorities to take more effective actions. Considering the results and analyses carried out with different fatality rates, it can be inferred that Brazil has a growing epidemic scenario and the real number of infected would already be between 1 and 5.4 millions.