▲BCG vaccine might be an opportunity to fight against COVID-19 (sources: Freepik)
Research teams around the world are now fully dedicated in vaccine and drug development as COVID-19 disease continues to spread. Meanwhile, they also seek to find the weakness of the virus by comparing the epidemic status in different countries. Researchers in the U.S.A. and Japan published a paper, “Association of BCG vaccination policy with prevalence and mortality,” on medRxiv discussing the relation between tuberculosis vaccine Bacillus Calmette-Guérin (BCG) and COVID-19. They found that the BCG vaccine can suppress the spread of COVID-19 to some degree.
Dr. Salal and Dr. Miyakawa collected information from 136 countries and categorized them into three groups: the country currently administers the BCG; the country used to administer the BCG and currently does not; the country has never administered the vaccine. The researchers used linear regression to analyze whether the total cases, deaths, and the death rates of COVID-19 are related to BCG vaccine policy.
According to the research, the rate of total cases per one million populations and the rate of death per one million populations were associated with the BCG vaccine policy in the country. The result shows the correlation of BCG vaccine and COVID-19 cases and deaths after excluding other factors, such as average temperature and life expectancy.
The team also conducted a chi-square test to check the significant impact of BCG vaccine on the COVID-19 spreading status. They found that there were significant differences in the spread of COVID-19 when considering the BCG policy (p=0.0002). Besides, the result still shows significant differences after excluding countries with low life expectancy, which would influence the analysis. Therefore, the research team concluded that there is a certain relation between BCG vaccine and the prevalence and mortality of COVID-19.
The research team explained that it might be resulted from the vaccine’s ability to enhance the human immune system. This hypothesis is supported by past clinical researches which indicate that tuberculosis vaccine BCG can trigger human immune B cells and T cells and stimulate innate immunity for a prolonged period to strengthen our immune system.
Finally, the team recommended further research to take into account of other factors that might affect the COVID-19 cases and mortality, such as policy and culture, to provide more solid evidence on the hypothesis of BCG’s positive effect on combating COVID-19.
Sala, G. and Miyakawa T. (2020) Association of BCG vaccination policy with prevalence and mortality of COVID-19. MedRxiv. Available from: https://www.medrxiv.org/node/75332.external-links.html [Accessed 17 April 2020]