Fig. 1

Times of observations. After a COVID-19 vaccination, participants received a short-term survey 14 days after the vaccination and a long-term survey 40 days after the vaccination. Additionally, everyone received a follow-up survey 124 days after the vaccination. If the interval between the two doses was less than 6 weeks, the participant did not receive the first long-term survey to avoid confusion by receiving two surveys in a short period regarding two different vaccinations. If the interval between the two doses was 10 weeks or longer, they did not receive the second long-term survey for the same reason. If the follow-up survey was sent 40 days after the second vaccination, this survey represents the second long-term as well as the follow-up survey