The potential impact of COVID-19 on tuberculosis trends in Japan

The COVID-19 pandemic impacted tuberculosis epidemiology worldwide, and Japan was no exception. This report analysed Japan's national tuberculosis surveillance data to explore the potential impact of COVID-19 on tuberculosis, by age group and place of birth, and to explore possible reasons behind the impact, if any. Overall since 2019, the observed number of notified cases was significantly lower than the number of expected cases. However, closer examination revealed that among Japan-born patients, this was true only for those aged 35-54 years and ≥ 65 years, while among those aged 25-34 years, the observed number of notified cases significantly exceeded the expected cases. Among foreign-born patients, the observed number of notified cases was significantly lower than that of expected cases for those aged 0-24 years and ≥ 65 years. Examination of changes in the modes of detection during the pre- and post-COVID-19 periods revealed that the impact of COVID-19 affected screening opportunities for tuberculosis among various populations differently, which in turn may partially explain the discrepancies between the observed and expected cases among those in different age groups and with different places of birth. A detailed study may be helpful in further understanding the interaction between the impact of COVID-19 on tuberculosis in the short and long-term.