The number of people infected and killed by the new coronavirus varies greatly from country to country.As an explanation for this fact, it is argued that the BCG vaccination obligation system may be involved.However, at present, the conclusion is not clear from the methodical problems associated with the analysis of international comparative data.

　In this study, we focused on the rate of increase in the number of infected people and the number of deaths in the first 30 days of the epidemic in each country.This eliminates the effects of reporting bias, and after statistically controlling various confounding factors, attempts to compare countries that have required BCG vaccines until at least 2000 and those that do not, for a total of 130 countries. Was done.

　As a result, the rate of increase in both the number of infected people and the number of deaths was significantly lower in countries that required BCG vaccination until at least 2000, compared to those that did not.In addition, similar results were seen when the period was set to the first 15 days of the epidemic.

　In addition, the effect of the obligation to inoculate the BCG vaccine seen here is quite large.For example, the United States has never institutionally mandated BCG vaccination, but if vaccination was institutionalized decades ago, the total number of deaths on March 2020, 3 could be estimated at 30. ..This is about 667% of the actual number (2467).

　This result suggests that the institutionalization of BCG vaccination obligations may suppress the epidemic of the new coronavirus in the future.In the future, it will be necessary for each country to discuss how to adopt and maintain such a system.

Paper information:[Science advances] Mandated Bacillus Calmette-Guérin (BCG) vaccination predicts flattened curves for the spread of COVID-19