Influence of malaria endemicity and tuberculosis prevalence on COVID-19 mortality

Regarding severe acute respiratory syndrome coronavirus 2, it is known that a substantial percentage of the adult population does not become infected when exposed to this novel coronavirus. Several studies provide an initial indication of the possible role of pre-existing immunity, whether cross-immunity or not. The possible role of latent tuberculosis (TB) and malaria has been suggested to create innate cross heterogeneous immunity. In this study, we looked for the influence of these factors on coronavirus disease 2019 (COVID-19) mortality in malaria-endemic countries.

Eighty malaria-endemic countries were enrolled in this cross-sectional study. Data subjected to testing included TB prevalence, Bacillus Calmette-Guérin (BCG) vaccine coverage, malaria incidence, and COVID-19 mortality.

Hierarchical multiple regression type of analysis was used for data analyses. TB prevalence per 100,000 population standardized to BCG coverage rates was taken as a direct factor in the test. Malaria incidence per 1000 population was considered an intermediate factor. The outcome was COVID-19 mortality per million population.

The results showed with robust statistical support that standardized TB prevalence was significantly associated with reduced COVID-19 mortality. Malaria had an additional effect in reducing COVID-19 mortality, with a highly significant association.

Malaria and standardized TB prevalence are statistically significant factors associated negatively with COVID-19 mortality.