Vaccines are the most effective means for preventing infectious diseases. Achieving high vaccine coverage is crucial for mitigating the negative effects of diseases that can be prevented using a vaccine. However, as with any pharmaceutical product, no vaccine is entirely free from the adverse events, which contributes to vaccine hesitancy [1]. Vaccine hesitancy refers to a “delay in acceptance or refusal of vaccination despite availability of vaccination services [2].” It is recognized as one of the top 10 substantial threats to global health [3].

The COVID-19 pandemic has profoundly impacted global health since 2020. Although the fatality rate has decreased with the emergence and spread of the Omicron variant, the disease burden still remains significant for both children and adults due to its high disease incidence rate [4,5]. Similarly, influenza is another major respiratory infectious disease. While the global incidence of influenza decreased during the first two years of the emergence of the COVID-19 pandemic [6], surges in its incidence have been observed in multiple countries since the 2022–2023 season [7,8].

Both COVID-19 and influenza are preventable through the use of vaccines, yet vaccine hesitancy remains a challenge. Parents or caregivers usually decide whether children should receive vaccinations and parental vaccine hesitancy has also been reported for both COVID 19 and influenza vaccines [9,10]. Some studies have reported that providing appropriate information about vaccine benefits (e.g., effectiveness) and risks of vaccination improve parental willingness to vaccinate their children [11,12]. Therefore, transparent communication about both the benefits and risks of influenza and COVID-19 vaccines is crucial. Given the considerable burden posed by both diseases, evaluating the factors influencing the intention of parents to vaccinate their children and the reasons behind vaccine hesitancy is essential for improving vaccine confidence and potential interventions to address this issue.

In Japan, since 2024, both COVID-19 and influenza vaccines have been voluntarily administered, and the vaccinees are required to pay the total vaccination cost, except for the elderly, for whom these vaccinations are provided as routine vaccinations, whereas part of the vaccination cost is subsidized. Thus vaccine costs can be another barrier to receiving these vaccines in the Japanese population, especially for children and young adults who may be under financial constraints. Evaluating parental willingness to pay for COVID-19 or influenza vaccination of their children is valuable not only for analyzing health economic factors related to these two respiratory diseases but also for guiding governments and local public health sector policies on potential subsidization of these vaccines (if needed).

The primary objective of this study was to evaluate the intention of parents to vaccinate their children against COVID-19 and influenza during the 2024–2025 season by providing them with vaccine information. The secondary objective was to assess the willingness of parents to pay for their children to receive COVID-19 and influenza vaccinations.