They also cautioned that the study had limitations which prevent conclusions from being drawn regarding the benefit of the BCG vaccine against COVID-19.
Scientists have compared volunteers who had received the BCG vaccine -- originally made against tuberculosis -- with those who did not, and have found that the immunised individuals "did not get sick more often, or become more seriously ill" during the ongoing COVID-19 pandemic. The study, published in the journal Cell Reports Medicine, evaluated a group of healthy volunteers who received the BCG vaccine in the five years before the ongoing pandemic, and compared their immune system function to that of healthy volunteers who were not administered the shots.
According to the scientists, including those from Radboud University in the Netherlands, the Bacille Calmette-Guerin or BCG vaccine was originally intended to treat tuberculosis, but was later proven to provide a long-lasting, general boost to the immune system. The current study determined if there was an effect of this vaccine on the symptoms attributable to infection with the novel coronavirus. It showed that those who received the vaccine did not have more symptoms, did not get sick more often, or become more seriously ill, during the first wave of the COVID-19 pandemic in the Netherlands.
"What the comparison between the groups shows is that at least those who received the vaccine did not get sick more often or become more seriously ill. It therefore does not hurt to vaccinate people with BCG," the scientists noted in a statement. The researchers noted that the country reported a lower number of sick people in the period March-May 2020 among the BCG-vaccinated group, with lower incidence of extreme fatigue among the vaccinated individuals. However, they also cautioned that the study had limitations which prevent conclusions from being drawn regarding the benefit of the BCG vaccine against COVID-19.
"It is very important to confirm that someone who has been vaccinated with BCG does not experience any increased symptoms during the COVID-19 pandemic. Although we see less sickness in the people who have had the BCG vaccination, only the ongoing prospective BCG vaccination studies can determine whether this vaccination can help against COVID-19", said study co-author Mihai Netea from Radbound University.
The scientists believe clinical randomised trials evaluating the BCG vaccine's effects against COVID-19 -- currently underway in several parts of the world -- can answer this question.
