Given the systemic immunogenic effects of Bacillus Calmette-Guérin (BCG) therapy in patients with bladder cancer and its non-specific immunogenic effects in viral respiratory diseases, we aimed to study severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in bladder cancer patients with a history of BCG therapy. In the present study, all bladder cancer survivors with a history of BCG therapy were identified and included in the study according to the data recovered from the UORC (Uro-Oncology Research Center) registry database. These patients were followed up in terms of acquiring coronavirus disease 2019 (COVID-19). Among the studied patients, 102 eligible bladder cancer patients with a history of BCG therapy entered the study. The males constituted the majority of the patients (86.3%), and more than half of the study population (55.9%) were above 65 years old. Among the understudy patients, 12.7% were confirmed for COVID-19. The study results did not show a statistically significant association between the time and number of BCG therapy courses and SARS-CoV-2 infection. Although no statistically significant association was observed between receiving BCG therapy and developing COVID-19, the infection rate in patients who had recently received BCG therapy was lower than those who had received therapy more than a year ago.

Mycobacterium tuberculosis has infected more than two billion individuals worldwide, of whom 5%–10% have clinically active disease and 90%–95% remain in the latent stage with a reservoir of viable bacteria in the macrophages for extended periods of time. The tubercle bacilli at this stage are usually called dormant, non-viable, and/or non-culturable microorganisms. The patients with latent bacilli will not have clinical pictures and are not infectious. The infections in about 2%–23% of the patients with latent status become reactivated for various reasons such as cancer, human immunodeficiency virus infection, diabetes, and/or aging. Many studies have examined the mechanisms involved in the latent state of Mycobacterium and showed that latency modified the expression of many genes. Therefore, several mechanisms will change in this bacterium. Hence, this study aimed to briefly examine the genes involved in the latent state as well as the changes that are caused by Mycobacterium tuberculosis. The study also evaluated the relationship between the functions of these genes.