We appreciate the reviewer's comment to our article on the correlation between the national BCG vaccination policy and coronavirus disease 2019 among Organisation for Economic Co-operation and Development countries as of April 20, 2020. In this letter, we further updated the data up to November 1, 2020, and found that the updated results also arrive at the similar conclusion as the accepted article.
Keywords: COVID-19; OECD; bacillus Calmette–Guerin vaccine; coronavirus infections; epidemiology; trained immunity.
© The Author(s) 2022.