“Mortality due to COVID-19 is reduced in countries where the vaccination of newborns with BCG, a vaccine to prevent tuberculosis, has been compulsory since the first half of the 20th century.”, said dr. Mihály Ruppert, PhD student explained while presenting a recently published epidemiological study.
Based on the results of the study, Hungary is one of these countries with possibly favourable circumstances, where the vaccine was introduced in 1954. Clinical trials proving the epidemiological observations will be launched in the following days and weeks all around the world.
The epidemic caused by COVID-19 has grown into a pandemic in a few weeks. Although the infection is present in every continent, there are significant differences between countries regarding the number of people infected and the death rates. Recent research suggests that the diverse methods of vaccination may contribute to the phenomenon, apart from the differences in cultural norms and the quality of health care.
According to a recent epidemiological study there is a correlation between the use of the BCG vaccine (Bacille Calmette-Guérin) developed to prevent tuberculosis and COVID-19 infections and the course of the disease. Data suggest that COVID-19 infection leads less likely to the death of patients in countries where neonatal BCG vaccination has been compulsory since the first half of the 20th century, including Brazil and Japan administering vaccinations since 1920 and 1937 respectively. On the other hand, in countries where BCG vaccination has been suspended (eg. Spain, France) or compulsory vaccination has never been introduced (eg. Italy) the mortality rate of the viral infection is high. Given that COVID-19 is a major threat to the elderly, the benefits of the BCG vaccine are also less pronounced in countries, where it was introduced relatively late (eg. in 1984 in Iran). In Hungary, neonatal BCG vaccination has been compulsory since 1954, thus Hungary is among the countries with more favourable conditions.
The exact molecular mechanism which activates the BCG vaccination against tuberculosis, COVID-19 and other upper respiratory tract infections is very little known. Data from some animal studies suggest that the pleiotropic protective effect of the BCG vaccine enhances the formation of inflammatory mediators, which boost non-specific antiviral immunity. Further basic research is needed to prove this.
Knowledge is also limited regarding the amount of time that has to elapse between the administration of the BCG vaccine and the development of protection against COVID-19. Partly in response to this question and partly to prove the epidemiological observation itself, several clinical trials are to be launched in the next couple of days and weeks all around the world. The Australian BRACE study is of particular note as nearly 4,000 health care workers are to be vaccinated.
Dr. Mihály Ruppert
Translation: Ágnes Raubinek
Source: Correlation between universal BCG vaccination policy and reduced morbidity and
mortality for COVID-19: an epidemiological study. Aaron Miller, Mac Josh Reandelar, Kimberly Fasciglione, Violeta Roumenova, Yan Li, and Gonzalo H. Otazu
doi:https://doi.org/10.1101/2020.03.24.20042937.
