Although COVID-19 vaccination was approved for younger children in Japan in October 2022, uptake rates remain critically low. This study aimed to investigate Japanese parents' intentions, hesitators' probability of positive intention change, and factors that motivate COVID-19 vaccination. Parents with a 6-month to 4-year-old child living in Japan participated in this internet-based, cross-sectional survey conducted from December 19, 2022, to January 4, 2023. The modified Poisson regression analysis was used to assess the probabilities of changing intention by each motivator when comparing the degree of hesitancy among hesitators, and the Poisson generalized estimating equations were used to compare the probabilities of changing intentions by potential motivators within hesitant individuals. Among 12,502 participants, 10,008 (80.1%) were hesitators. Parents with lower hesitancy levels were more likely to be motivated to vaccinate their children through potential motivators. Vaccine hesitators were motivated to vaccinate their children, particularly by proven vaccine effectiveness (including "protecting children from getting sick" with a probability ratio [PR] of 3.7 [95% confidence interval (CI) 3.5-3.9] and "less likely to infect adults" with a PR of 2.9 [95% CI 2.8-3.1]), as well as vaccine safety (including "safe vaccination of millions of children" with a PR of 3.1 [95% CI 3.0-3.3]) compared to injunctive norm (including "community leader recommendation"). Therefore, initially addressing parents with low hesitancy levels is an effective strategy that motivates COVID-19 vaccination. Also, providing evidence-based information about COVID-19 vaccine efficacy and safety that is consistent with parents' needs is crucial.
Keywords: COVID-19; Japan; Vaccine hesitancy; children; motivator; parents; social norm.