BCG vaccination and its possible effects on the acceleration of incidence and mortality by the new coronavirus: second step

Introduction: The pandemic caused by the new coronavirus brought difficulties to global health and the economy. The race for an effective therapy to control the disease is launched, and an understanding of the pathophysiology is necessary. The BCG (bacillus Calmette–Guérin) vaccine activates and modulates innate immunity, and its protective effect against the new coronavirus should be investigated. Objective: To compare the incidence, mortality, and lethality rates of COVID-19 according to the vaccination program for BCG of the main countries affected by the pandemic. Methods: The second of three phases of a data survey was carried out from official sources on the number of cases and number of deaths by COVID-19 between April 11 and May 11, 2020, and the incidence, mortality and lethality rates were calculated and compared among predefined groups according to their BCG vaccination programs. In the same way, the acceleration rate between the groups in the period under analysis was performed. Results: Similar to the results found in the first phase in April, the countries without an active BCG vaccine program had, on average, 3.96, 9.34, and 2.35 (p < 0.001) higher ratios in the incidence, mortality and lethality rates, respectively. Conclusion: There is a protective connection between the presence of active BCG vaccination programs and the number of cases and deaths per inhabitant in the countries studied, showing a possible cross effect of innate immunity against the new coronavirus.