SANTA BARBARA, Calif. — From hydroxychloroquine to azithromycin, there is a growing list of medications that may or may not help patients with coronavirus. A new study is debating whether the Bacille Calmette-Guerin (BCG) vaccine is keeping severe symptoms of COVID-19 away or if it’s just a coincidence. Researchers say adults who received the common tuberculosis injection as children are no better off than those who have not.
UC Santa Barbara’s Clément de Chaisemartin and his cousin, Luc de Chaisemartin of Paris-Saclay University, find health records in Sweden show children vaccinated in 1975 are just as susceptible to the virus as children who were not given BCG.
Previous studies, including one in the Netherlands, finds patients given the BCG shot receive a long-term boost to their immune system. Vaccinated patients in that study are also suffering less severe symptoms during the COVID-19 outbreak.
De Chaisemartin’s investigation began after the UC Santa Barbara assistant professor of economics realized he was vaccinated with BCG in his native France, but his youngest brother was not. Many countries phased out BCG vaccinations and booster shots recently with tuberculosis becoming a rare illness.
“I just went onto Wikipedia and tried to find a country were the BCG interruption was less recent, so that the people affected would be older and at higher risk of COVID-19,” Chaisemartin explains in a university release.
Sweden’s vaccination dividing line
The study reveals Sweden stopped requiring BCG vaccines for children on April 1, 1975. The cousins look at Swedish residents born in March and April of that year, to see how each group is handling the pandemic 45 years later.
The results show COVID-19 cases, hospitalizations, and deaths per capita are very similar between the vaccinated and unvaccinated groups. Although countries that had BCG vaccine mandates seem to be faring better during the pandemic, the study suggests other health factors are responsible.
“Our study shows that this correlation is probably not due to the BCG vaccination, but rather to some omitted variable,” the researcher contends. “This raises the question as to what this omitted variable is, because if it is something that policymakers can act upon, then maybe we would have something actionable against COVID-19.”
Is it the BCG vaccine or something else?
Study authors theorize countries with a history of using BCG are benefiting more because of their focus on public health, rather than the strength of the vaccine.
“Countries that have many mandatory vaccinations may be countries where public health agencies are more powerful,” de Chaisemartin adds. “So maybe those public health agencies are also able to implement effective policies against COVID-19.”
The assistant professor also believes communities which regularly live with mandatory vaccination policies may have a tendency to avoid risky behavior. De Chaisemartin adds the public in these countries may be adhering to lockdown orders better, lowering their risk of contracting COVID.
While childhood vaccinations seem to have no direct link to protecting against the coronavirus, researchers say studies are still examining if a recent BCG shot can make a difference.
“Without sound evidence that BCG protects against COVID-19, it is important to wait for the results of the ongoing trials, rather than deplete stocks of a vaccine already difficult to get for those who really need it, namely children in countries with a high prevalence of tuberculosis.”
The study appears in the journal Clinical Infectious Diseases.