Safety and adverse effects of the coronavirus disease 2019 vaccine among the general Japanese adult population

OBJECTIVES: We aimed to identify and explore the association between the characteristics of coronavirus disease 2019 (COVID-19) vaccine recipients and the types of vaccine-related adverse effects in the general Japanese adult population. METHODS: An anonymous self-report questionnaire was distributed to 4393 students and 1657 white and blue-collar workers (N=6050). Data on vaccine-related adverse effects were collected twice, once after each vaccination. The data collection was performed daily from the day of injection (D0) until the sixth day after injection (D6). The list of adverse effects comprised local reactions at the injection site (pain, redness, and swelling) and systemic symptoms (fever, fatigue, headache, myalgia, joint pain, chills, and nausea or vomiting). The Student's t-test and Mann–Whitney U test were used to analyze parametric and non-parametric data, respectively. RESULTS: The incidence of adverse reactions to the COVID-19 vaccination was higher after the second dose (e.g., redness: 47.1%; swelling: 60.6%; fever: 80.6%) of vaccination than after the first dose (e.g., redness: 16.4%; swelling: 37.2%; fever: 11.9%). Women reported adverse reactions to the vaccination more frequently. Some adverse reactions included more symptoms in younger participants, and participants with a lower body mass index were more at risk for these symptoms. CONCLUSIONS: Some adverse reactions to the COVID-19 vaccination are a greater risk of symptoms in the younger group, women, and participants with lower BMI. Care should be taken to monitor women, younger people, and individuals with a low body mass index for adverse effects after receiving the COVID-19 vaccination.