Factors associated with seasonal influenza vaccine uptake among children in Japan

Background: Seasonal influenza vaccine was once part of the routine immunization schedule that is routinely offered to all children in Japan, but it is now excluded from the schedule. This study aimed to investigate factors influential to parents' decision to have their children receive seasonal influenza vaccine, as well as types of seasonal influenza vaccine information that is given to parents. Methods: We conducted a cross-sectional online survey of 555 participants who have at least one child younger than 13 years of age. Respondents were asked to categorize the history of influenza vaccination of their youngest child as either 'annual', 'sometimes', or 'never'. Participants were also asked about potentially influential factors in their decision to have their children receive a seasonal influenza vaccine. Results: A total of 75% of respondents answered that their youngest child had received a seasonal influenza vaccine, and 57% of respondents answered that their child receives the vaccine every year. The higher income group was more likely than the lowest income group to have a history of influenza vaccine uptake. A recommendation from a pediatrician or school/nursery to have their child vaccinated was also positively associated with a history of influenza vaccine uptake. The most common reason for a pediatrician's recommendation was 'it leads to milder symptoms if infected'. Conclusions: The main finding of the study is a significant association between household income and influenza vaccination of the youngest child in the household. We also found that cost could be a barrier to vaccinating children in low income households and that information from pediatricians and schools/nurseries could motivate parents to have their children vaccinated.