Reasons for unvaccinated booster dose of COVID-19, adverse reaction after vaccination, and COVID-19 infection status among those with COVID-19 booster vaccination hesitancy

Background

We have previously reported reasons for vaccine hesitance among those who did not receive the coronavirus disease 2019 (COVID-19) vaccination. However, the detailed causes of hesitancy related to booster vaccinations remain largely uninvestigated. This study aimed to describe why individuals who received one or two vaccine doses avoided booster shots.

Methods

In March 2023, a cross-sectional Internet survey was conducted to investigate the reasons for vaccine hesitancy and the extent of adverse reactions following vaccination among individuals who had not received a booster dose in Japan. Survey items included social demographics, comorbidities, history of SARS-CoV-2 infection, history of COVID-19 vaccination, adverse reactions to COVID-19 vaccines, and reasons for vaccination decline. The reasons for avoiding vaccination were summarized.

Results

In this study, 545 individuals were included: 262 did not receive vaccination, 21 received one dose, and 263 received two doses by March 2023. The most common reason for avoiding subsequent booster doses among individuals who received one or two doses of the vaccine was concerns about adverse reactions (n[%] = 192 [67.8 %]), followed by concerns about vaccine safety (n[%] = 154 [54.4 %]). The proportion of vaccine safety concerns was lower in the booster vaccination hesitant group than in the non-vaccination group (p < 0.001). The group that avoided booster vaccination due to adverse reactions experienced all types of adverse reactions more severely than those for which adverse reactions were not a reason for vaccine hesitancy.

Conclusions

The most prominent reason for avoiding booster doses after receiving one or two doses of the COVID-19 vaccine was related to concerns regarding associated side effects. To prevent vaccine hesitancy regarding booster doses, including COVID-19, the strategy for reducing discomfort caused by these adverse reactions should involve the first and second doses.