Repurposing BCG and MMR Vaccines for Combating COVID-19: A Review and Opinion Based on Clinical Evidence

Abstract

Our review comprehends past and recent developments encircling the two vaccines, BCG and MMR, which have efficacy lasting 10 years and are known to trigger the production of Interferon and various cytokines. BCG has depicted long-lasting effects, reduction in mortality, and hospitalizations associated with various diseases in different age groups as per studies across Sweden, West Africa, Spain, and Indonesia. Clinical trials are in progress in Holland, Australia, and Germany to study its effects on COVID-19. Most Asian countries with childhood BCG vaccination programs have shown lower COVID-19-related per capita death rates. The MMR vaccination has shown a reduction in hospitalizations and COVID-19-related deaths in about 11 countries, and a randomized clinical trial has been proposed in New Orleans. Reasons such as inhibition of pulmonary inflammation and structural similarity have been cited for such consequences. BCG and MMR may serve to shorten the duration of infection, minimize harmful pathology, reduce hospitalization rates, and curb the spread of the disease, but more research is required to assess the associated risks, especially for the elderly and people with comorbidities who are prone to severe complications of COVID-19.