COVID-19 Incidence and Mortality in Patients Recovered from Tuberculosis: a Retrospective Cohort Analysis of the National Health Insurance in the Republic of Korea.

Tuberculosis (TB) is an endemic respiratory disease in several countries, including South Korea. The coronavirus disease 2019 (COVID-19) may pose greater risks to individuals with pre-existing respiratory diseases, but there are few reports on how the state after recovery from TB affects COVID-19 infection and mortality. This study aimed to investigate the susceptibility and mortality of COVID-19 in patients with a history of TB. We retrospectively analyzed data from the National Health Insurance Service of Korea. We extracted individuals with TB from 2011 to 2019 and matched them with a population-based control group. The main outcomes were COVID-19 incidence and death within 30 days of infection. The study included 138,278 matched pairs of individuals with and without a history of TB. COVID-19 incidence was slightly lower in the TB group (38.0% vs. 38.4%, P = 0.023). Subgroup analysis showed significantly lower COVID-19 incidence in the pulmonary TB group compared to controls (P = 0.001). However, the mortality rate was higher in the TB group (0.9% vs. 0.7%, P < 0.001). This study showed that TB has a slightly protective effect against COVID-19 infection but increases the mortality rate. These findings may guide future research on the interaction between TB and COVID-19.