Impact of routine infant BCG vaccination in young generation on prevention of local COVID-19 spread in Japan

Kinoshita, Masako; Tanaka, Masami

OBJECTIVES: In Japan, the first case of coronavirus disease 2019 (COVID-19) was diagnosed on January 15, 2020 and subsequent infections rapidly increased. The Bacillus Calmette-Guérin (BCG) vaccination program is the principal element of tuberculosis control in Japan. We investigated the impact of routine infant BCG vaccination on prevention of local COVID-19 spread. METHODS: Data on the prevalence of SARS-CoV-2 infection, annual routine infant BCG vaccine coverage (represented by the number of BCG vaccinations per live births), and other candidate factors in each prefecture were obtained from the official notifications database in Japan. We analysed the association of vaccine coverage with the prevalence of SARS-CoV-2 infection. RESULTS: The BCG vaccine coverage in 1999–2002, 2004, and 2012 in five prefectures with no COVID-19 infections was significantly higher than that in five prefectures with a high prevalence of infections (Mann-Whitney U test, p<0.05). The prevalence of SARS-CoV-2 infection was significantly negatively correlated with BCG vaccine coverage in 2004 and was significantly positively correlated with age groups 20–34 and 40–54 years (Spearman's rank correlation, p<0.01). CONCLUSIONS: Our findings suggest that routine infant BCG vaccination coverage in young generation had a significant impact on prevention of local COVID-19 spread in Japan.