We know the SARS-CoV-2 virus afflicts certain populations more than others. In the US, severe disease and death from COVID-19 more often affects individuals with underlying health conditions and the elderly. This leaves individuals living in long-term care facilities extremely vulnerable, especially when no vaccine specific to SARS-CoV-2 is currently approved for widespread use and no treatments have been developed. With nearly 1.3 million Americans living in these types of facilities, there is a sense urgency to finds some means of preventing further loss from COVID-19 in this population.
One promising posibility is the Bacille Calmette-Guerin (BCG) vaccine. Since its creation nearly a century ago, the BCG vaccine has been used to prevent upper respiratory infections, including tuberculosis. For decades, children have been vaccinated routinely with BCG to prevent tuberculosis in countries around the world, highlighting its safety and efficacy.
While vaccines for infections like the flu often don't confer immunity in adults as effectively as they do in children, there is data to suggest that BCG administered to adults is likely to have a protective effect. Studies like the ACTIVATE 1 study conducted in 2017 showed an 80% reduction in repiratory infections in individuals over the age of 65 who were vaccinated with BCG. Another study performed by a team in the Netherlands followed up with elderly individuals who had received a BCG vaccine within the last five years and found that individuals who had received a vaccine were less likely to report having had COVID-19 and, if they did have it, they reported more mild symptoms. Even from a country-level perspective, studies have shown that incidence and death rates from COVID-19 are lower in countries that routinely administer the BCG vaccine to their citizens. The sum of information like this establishes the connection between BCG vaccination and COVID-19 for researchers and lays the groundwork for new trials.
Clinical trials are underway around the world investigating the effects of BCG vaccination on COVID-19 in new high-risk populations. Many of these trials are investigating the protective effect of BCG vaccination in healthcare workers who have not previously received the vaccine. This information is valuable, but none of these trials are examining if BCG vaccination will protect those who are most vulnerable: elderly individuals in long-term care facilities.
Clinicians and researchers in The Department of Global Health and Social Medicine at Harvard Medical School are now starting a trial to answer this question. It's called BAC to the Past: BCG Against COVID-19 for the Prevention and Amelioration of Severe Disease Trial. If you are interested in learning more or would like to see if you are eligible, please visit the trial website or contact our department.