Role of BCG and Measles vaccination in protection against COVID-19 infection and severity of the disease: A pilot case-control study

Background: The role of BCG and MMR/Measles vaccination in reducing the burden of COVID-19 has been based on ecological data mostly. We planned this explorative pilot case-control study to under-stand the role of vaccination with Bacillus Calmette–Guerin (BCG) and measles administered as part of MMR vaccine on COVID 19. Methodology: A case-control study was conducted in AIIMS Patna during December 2020 and January 2021. A total of 100 COVID-19 patients confirmed by RT-PCR test were taken as cases, and for each case, age and gender-matched SARS-COV-2 negative individual was taken as control. A study tool containing a pre-tested semi-structured questionnaire was used. Results: The unadjusted odds of COVID-19 were found to be significantly higher among BCG vaccinated [1.88(1.03-4.4)] and MMR vaccinated individuals [5.06(2.34-10.90]. BCG vaccine was not found to have an independent effect on COVID-19 after adjusting for tobacco use, MMR vaccination status, unprotected contact with SARS-COV-2 positive patients, and co-morbidities. But Measles vaccine was found to inde-pendently increase the risk of COVID-19 [AOR: 4.505(1.8-11.3)]. Conclusion: BCG vaccination status was not found to be an independent predictor of COVID-19. Further studies with large sample size and better study design (cohort, randomized trials) need to be conducted.