This questionnaire survey was conducted at 11 hospitals in Japan to determine vaccination coverage against seasonal
influenza and the prevalence rate of
influenza among pregnant Japanese women. Of 2,808 postpartum women who gave birth at the 11 hospitals during the study period from March 1, 2014, to July 31, 2014, 1,713 (61 %) participated in this study and 876 (51 %) reported having received vaccination against
influenza in or after October 2013. Women aged <25 years had a significantly lower vaccination rate than those aged ≥25 years (31 % vs. 53 %, respectively; p = 0.0000). Eighty-seven (5.1 %) and 1,626 (94.9 %) women did and did not contract
influenza, respectively. Although prior birth did not affect overall vaccination coverage (50 % for primiparous vs. 53 % for multiparous), multiparous women had a significantly higher rate of contracting
influenza than primiparous women, irrespective of vaccination status (5.6 % vs. 2.2 % [p = 0.0216] and 9.7 % vs. 3.5 % [p = 0.0003] for women with and without vaccination, respectively). The 2013-2014 vaccination program significantly reduced the
influenza infection rate by 35 % (3.9 % vs. 6.3 % for women with and without vaccination, respectively; p = 0.0272). Seventy-two (83 %) of the 87 women took
antiviral agents for the treatment of
influenza and two (2.3 %) required hospitalization. These results suggested that pregnant Japanese women had a high level of concern regarding seasonal
influenza. However, campaigns targeting young pregnant Japanese women, as well as multiparous women, for vaccination are needed in order to further reduce the incidence of
influenza among pregnant Japanese women.