Tracking excess deaths associated with the COVID-19 epidemic as an epidemiological surveillance strategy-preliminary results of the evaluation of six Brazilian capitals

Abstract

Introduction: In March 2020, the World Health Organization declared the coronavirus disease (COVID-19) outbreak a pandemic. In Brazil, 110 thousand cases and 5,901 deaths were confirmed by the end of April 2020. The scarcity of laboratory resources, the overload on the service network, and the broad clinical spectrum of the disease make it difficult to document all the deaths due to COVID-19. The aim of this study was to assess the mortality rate in Brazilian capitals with a high incidence of COVID-19.

Methods: We assessed the weekly mortality between epidemiological week 1 and 16 in 2020 and the corresponding period in 2019. We estimated the expected mortality at 95% confidence interval by projecting the mortality in 2019 to the population in 2020, using data from the National Association of Civil Registrars (ARPEN-Brasil).

Results: In the five capitals with the highest incidence of COVID-19, we identified excess deaths during the pandemic. The age group above 60 years was severely affected, while 31% of the excess deaths occurred in the age group of 20-59 years. There was a strong correlation (r = 0.94) between excess deaths and the number of deaths confirmed by epidemiological monitoring. The epidemiological surveillance captured only 52% of all mortality associated with the COVID-19 pandemic in the cities examined.

Conclusions: Considering the simplicity of the method and its low cost, we believe that the assessment of excess mortality associated with the COVID-19 pandemic should be used as a complementary tool for regular epidemiological surveillance.

FIGURE 1:. Location of the six Brazilian capitals studied.

FIGURE 2:. Weekly mortality observed in 2020 (black line); expected (dotted) 95% confidence interval (gray area) for respiratory causes (right) and for all causes (left) by city. The dotted arrow indicates the date of confirmation of the first case and the black arrow indicates the date of the first confirmed death in the city. The yellow area represents the period for which the mortality data are still incomplete.

FIGURE 3:. On the left (A), correlation between mortality officially confirmed by COVID-19 in the cities examined and the estimated excess mortality; the equation suggests that for each notified patient, there were 2.5 excess deaths by week 16. On the right (B), officially confirmed deaths by COVID-19 and excess deaths per epidemiological week. Data for the cities of São Paulo, Recife, and Fortaleza are shown according to the date of death.