Mandated Bacillus Calmette-Guérin (BCG) vaccination predicts flattened curves for the spread of COVID-19

Abstract

Bacillus Calmette-Guérin (BCG) vaccination may reduce the risk of a range of infectious diseases, and if so, it could protect against coronavirus disease 2019 (COVID-19). Here, we compared countries that mandated BCG vaccination until at least 2000 with countries that did not. To minimize any systematic effects of reporting biases, we analyzed the rate of the day-by-day increase in both confirmed cases (134 countries) and deaths (135 countries) in the first 30-day period of country-wise outbreaks. The 30-day window was adjusted to begin at the country-wise onset of the pandemic. Linear mixed models revealed a significant effect of mandated BCG policies on the growth rate of both cases and deaths after controlling for median age, gross domestic product per capita, population density, population size, net migration rate, and various cultural dimensions (e.g., individualism). Our analysis suggests that mandated BCG vaccination can be effective in the fight against COVID-19.

Impact of Recommended Maternal Vaccination Programs on the Clinical Presentation of SARS-CoV-2 Infection: A Prospective Observational Study

“…On the other hand, and unlike Tdap and Influenza vaccines (both inactivated vaccines), it has been suggested the potential effect of live attenuated vaccines such as the Bacille Calmette-Guérin (BCG, Mycobacterium bovis vaccine) on reducing SARS-CoV-2 infection, by inducing a trained innate immune response [ 20 , 21 ]; this trained immunity is a non-specific response activated through epigenetic changes in myeloid cells and NK cells that lead to a long-term proinflammatory response and confers cross-protection against other pathogens [ 22 ]. Still, the development and administration of SARS-CoV-2 specific vaccines is crucial for limiting the COVID-19 pandemic [ 23 , 24 , 25 ], while the previous ones could be a complement to SARS-CoV-2 specific vaccines in certain settings until herd immunity is achieved with the latest.…”

Worldwide inverse correlation between Bacille Calmette–Guérin (BCG) immunization and COVID-19 mortality

“…Miller et al analyzed data of several countries as of March 21, 2020, and found a significant correlation between countries with universal BCG vaccination policy and reduced COVID-19 morbidity and mortality [ 7 ]. Berg et al have published a biweekly updated report since April 2020 analyzing the daily rates of COVID-19 case and death increase, and have shown that countries with mandated BCG vaccination policy consistently exhibit flattened curves (slower increases) [ 6 ]. A recent study by Escobar et al carried out detailed population comparisons, e.g., between former East and West Germany, and have found significant correlation BCG immunization and reduced COVID-19 deaths especially in European countries [ 18 ].…”

Immune responses during COVID-19 infection

“…Based on epidemiological reports identifying fewer confirmed cases of SARS-CoV-2 in countries implementing BCG vaccination, it has been postulated that "trained" immunity induced by BCG adjuvants could confer protection against SARS-CoV-2. [123][124][125][126][127] BCG vaccination has been shown to increase the immunogenicity of influenza virus-based vaccine and reduce acute lower respiratory tract infections in children. 127,128 Across 55 countries, BCG significantly mitigated the spread and severity of the COVID pandemic-19 109 .…”