Does having received the BCG vaccine in childhood have a protective effect?

An important public health message

Most of the studies published to date 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 those who received the BCG vaccine were also those who had the best survival, nor did they take into account certain factors that could have biased the analyzes.

“Our study convincingly showed that BCG, a potent booster of innate immunity, does not provide very long-term protection against COVID-19. This is not the result we were hoping for, but at least this question, which is particularly relevant for countries in the South, can be taken off the table ”, explains Dr Jacques Pépin, first author of the study and associate professor at University of Sherbrooke and the CHUS Research Center.

“Even if our results turned out to be negative, it is important to communicate them to the public, as they contrast with those obtained in previous studies, which had significant methodological weaknesses. Our results are therefore the most valid available on this subject to date ”, says Marie-Claude Rousseau, professor and researcher in epidemiology at INRS and corresponding author of the study.

The researcher recalls that a potential protective effect of the BCG vaccine against COVID-19 was the subject of great scientific and media interest very early in the pandemic.

“Over the past year, we have had 25 times more requests from the public to verify if they had received the BCG vaccine in their childhood,” explains Professor Rousseau, who is also scientific manager of the Quebec vaccination registry. BCG hosted by INRS, a unique computerized resource organization that lists 4.2 million vaccination certificates issued in the province between 1956 and 1992.

No long-term protection

The research team recruited 920 people who tested positive for the PCR test for COVID-19 at the Maisonneuve-Rosemont Hospital (HMR) of the CIUSSS de l’Est-de-l’ÃŽle-de-Montréal and the University Hospital Center of Sherbrooke (CHUS) between March and October 2020. In parallel, the control group consisted of 2,123 people who did not have COVID-19, but had another sample analyzed in microbiology laboratories during the same period.

“This project involved around twenty medical students from the University of Sherbrooke and the University of Montreal. They contacted participants by phone to complete a questionnaire. We would like to thank everyone who agreed to participate in this study, ”said Dr. Annie-Claude Labbé, study co-author and microbiologist and infectious disease specialist at HMR.

Only individuals born in Quebec between 1956 and 1976 were recruited. Their vaccination status was verified in the BCG vaccination registry of Quebec based on the information they provided to the research team. Of those who tested positive for COVID-19, 54% had received the BCG vaccine in childhood. This proportion was 53% in the control group.

Researchers have not found any long-term protective effect of BCG. Their analyzes checked for other factors such as the person’s type of job, biological sex, age, an index of material deprivation, and whether they lived in a rural or urban area.

“Although we expected to see a small protective effect, we were not surprised by the results. After all, the participants had received the vaccine decades ago. Of those who had received the vaccine more recently, at At the beginning of the 1970s, no protective effect was also However, the number of people was limited, considerably reducing the possibility of detecting a small effect, ”explains Professor Rousseau.

A vaccine of great interest

Professor Rousseau notes that some studies have suggested a short-term protective effect of BCG against COVID-19 and that clinical trials are underway internationally, which looks promising.

“It is interesting to see the renewed interest in this century-old vaccine, especially with regard to its effects that are not linked to tuberculosis, over the past five to ten years,” she concludes.

About the study

The article is “Does BCG provide long-term protection against SARS-CoV-2 infection? A case-control study in Quebec, Canada“by Jacques Pépin, Annie-Claude Labbé, Alex Carignan, Marie-Elise Parent, Jennifer yu, Cynthia Grenier, Stéphanie Beauchemin, Philippe De Wals, Louis Valiquette, Marie-Claude Rousseau (DO I: 10.1016 / j.vaccine.2021.08.019). It appears in Vaccine, (August 2021, online ahead of print), published by Elsevier.

The study received financial support from the CHUS Foundation.

Copies of this document are available on request for accredited journalists; please contact the Elsevier press room at [email protected] or +31 20 485 2719.

About the vaccine
Vaccine is the journal par excellence for those interested in vaccines and immunization. It is the official journal of the Edward Jenner Society and the Japanese Society for Vaccinology and is published by Elsevier

About INRS

INRS is a university dedicated exclusively to research and graduate training. Since its creation in 1969, INRS has actively participated in the economic, social and cultural development of Quebec and ranks first for the intensity of research in Quebec and in Canada. INRS is made up of four interdisciplinary research and training centers in Quebec City, Montreal, Laval, and Varennes, with expertise in strategic sectors: Water Earth Environment, Energy Materials Telecommunications, Urbanization Culture Society, and Armand-Frappier Health Biotechnology. The INRS community has more than 1,500 students, postdoctoral fellows, teachers and staff.


About the University of Sherbrooke

The University of Sherbrooke is at the heart of one of the of Quebec three major research centers. Recognized for its sense of innovation, the University of Sherbrooke is a key partner of higher and regional governments in promoting economic, cultural and social development. It has carved out a reputation for itself due, among other things, to the strong growth of its research activities in recent years, its success in technology transfers, as well as its initiatives in entrepreneurship and open innovation in collaboration with the industry and social circles.

SOURCE National Institute for Scientific Research (INRS)

For further information: Julie Robert, INRS Communications Department, 514 971-4747, [email protected]

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