A team of scientists from the National Institute for Scientific Research (INRS), the Université de Sherbrooke, the Université de Montréal and the Université Laval conducted the very first study on the Quebec population to compare childhood vaccination status in people with COVID-19 and in a control group. The works, published in the review Vaccine, shed new light on the possible link between the BCG vaccine (Calmette-Guérin bacillus) and COVID-19.
To date, most published studies have shown a correlation between BCG vaccination in the population and a lower death rate from COVID-19. However, according to the team of Quebec scientists, the methodology of these studies did not make it possible to determine whether the people who received the BCG vaccine were those who had a better survival rate or to consider whether certain factors could have biased the analyzes.
“Even if our results are negative, it is important, from a public health point of view, to communicate them to the public, since they go against those obtained in previous studies, which had methodological weaknesses. important. To date, they are therefore the most valid available on this subject ”, specifies Marie-Claude Rousseau, professor-researcher in epidemiology at INRS and principal author of the study.
The researcher recalls that the potential protective effect of the BCG vaccine against COVID-19 was the subject of great scientific and media enthusiasm very early in the pandemic.
The research team recruited 920 people who had obtained a positive result in a PCR test for COVID-19 at the Maisonneuve-Rosemont Hospital, part of the Integrated University Health and Social Services Center of the East. de-l’Île-de-Montréal, and at the Center hospitalier universitaire de Sherbrooke between March and October 2020. In parallel, the control group included 2123 subjects who were not affected by COVID-19, but who had at minus one other analysis performed in the microbiology laboratory during the same period.
“This project was carried out thanks, among other things, to the participation of some twenty medical students from the University of Sherbrooke and the University of Montreal. They communicated by telephone with the participants so that they could answer a questionnaire. We are also very grateful to all these people who agreed to take part in this study, ”says Dr.re Annie-Claude Labbé, co-author of the study, professor in the Department of microbiology, infectiology and immunology at UdeM and doctor at Hôpital Maisonneuve-Rosemont.
A few studies have also talked about a short-term protective effect of the BCG vaccine against COVID-19 and clinical trials are underway internationally, sparking renewed interest in this century-old vaccine.