According to the study published in the journal Clinical Microbiology and Infection, the BCG vaccine, which is used to prevent tuberculosis, does not shield older patients with co-morbid conditions from coronavirus-related disease symptoms. 

In the early stages of the pandemic, there was a critical medical and societal need for a vaccine that could guard against the COVID infection. The Bacillus Calmette-Guerin (BCG) vaccine was one potential treatment to fill the gap until corona vaccines and antivirals became available that were effective. The BCG vaccine also has the added benefit of triggering a broader innate immune system defense than just against TB.

The placebo-controlled BCG-PRIME trial was conducted between September 2020 and December 2021 on a total of 6,112 older adults with co-morbidities who were 60 years of age or older. Through hospital wards, outpatient clinics, and anticoagulant services, participants were gathered. Following vaccination, patients underwent six months of hospital-based monitoring.

The study′s findings revealed that elderly individuals with co-morbidities who received the BCG vaccine experienced COVID-19 infection at the same rate as those who received a placebo (129 vs. 115). Additionally, they discovered that there was no difference between the two groups in terms of mortality, the number of significant adverse events, the number of COVID-19-related hospitalizations, or the number of respiratory infections requiring medical attention.