The necessity of urgent low-cost epidemiological studies with short duration about the role of BCG vaccine in preventing and controlling of COVID-19 in Iran

Abstract

The 2020] Objective (s ) : Currently there is no effective treatment and vaccine for COVID-19. However, several studies showed that BCG vaccine has long lasting positive non-specific effects on several infectious and autoimmune diseases via ‘trained immunity’ mechanisms. Along with these exceptional properties of this vaccine, few ecological studies showed controversial association between the national vaccination policies and morbidity and mortality rate of COVID-19. Methods: This Article, reviewed the immunological mechanisms that explain the enhanced immunity by BCG vaccine against COVID-19. Also the conducted ecological studies and the clinical trials that are being conducted by few countries were reviewed. Results: Considering Iran’s national BCG vaccination program and the low evidence level of ecological studies, we suggest to Iranian universities of medical sciences to conduct low-cost but better epidemiological studies with short duration, using tuberculin test. These studies including case-control, historical cohort and survival analysis studies, which will assess the association between immunity against tuberculosis and COVID-19 and its prognosis. The results of these studies may guide researchers about the necessity of conducting clinical trials among high risk groups like hospital staffs. Conclusion: Also as few studies have shown BCG vaccine has therapeutic effects on patients with type 1 diabetes and multiple sclerosis, conducting clinical trials among Iranian patients can measure not only the preventive effect of BCG vaccine against COVID-19 but also the therapeutic effect on these two chronic diseases