This study investigated the implementation status, attitudes, and practices regarding maternal pertussis vaccination in delivery facilities in Kanagawa, Japan. We conducted a questionnaire survey of pertussis vaccination during pregnancy at 125 delivery service facilities, excluding midwifery clinics, in Kanagawa Prefecture from June 18 to July 20, 2020. The questionnaire comprised multiple-choice items, with single or multiple answers depending on the question. Of the 125 facilities surveyed, valid responses were obtained from 72 facilities (58%). There were 41 primary clinics with birthing facilities (57%), 16 general hospitals (not designated perinatal centers) (22%), 10 regional perinatal centers (14%), and five tertiary perinatal centers (7%). None of the facilities administered pertussis vaccination during pregnancy. Forty facilities (56%) reported knowledge of the severity of neonatal and infant pertussis infections. Twenty-three facilities (32%) reported knowledge of the prevention of pertussis infection by vaccination during pregnancy. All facilities reported willingness to consider vaccination if included in the Japanese guidelines. In Japan, the pertussis vaccination during pregnancy is not highly practiced by obstetricians; thus, it is not as popular as in other countries. Further studies are needed to promote strategies to prevent pertussis infection in the neonatal and infant periods.

Background/Objective: Maternal immunization is highly recommended, particularly in developed countries. However, its awareness among pregnant women in Japan remains low. This study aimed to assess the awareness and attitudes toward maternal immunization among pregnant women in Japan and to identify the factors that may promote its acceptance. Methods: We conducted a cross-sectional questionnaire survey among pregnant women attending antenatal checkups at nine facilities in Kanagawa Prefecture, Japan, from August 2024 to January 2025. The survey assessed knowledge and intention regarding maternal immunization for influenza, pertussis, respiratory syncytial virus (RSV), and group B streptococcus (GBS) as well as attitudes toward vaccination costs and information sources. Results: Overall, 523 respondents were included in this study. The overall awareness of maternal immunization was 16%. Willingness to receive vaccinations during pregnancy was reported for influenza (68%), pertussis (58%), RSV (59%), and GBS (71%). A common reason for vaccine hesitancy included uncertainty about its effects on the fetus. The key factors associated with vaccine acceptance were higher educational attainment and prior knowledge of maternal immunization. Regarding costs, most respondents were willing to pay up to JPY 5000 (approximately USD 35). The most frequently prioritized sources were explanations from physicians, followed by explanations from midwives. Conclusions: Despite low awareness, vaccination intention was comparable to that reported in other countries. Points that may contribute to improved vaccine uptake were also identified. These findings may lead to the prevention of infectious diseases in newborns and infants in Japan and possibly improve public health.

Maternal pertussis immunization prevents severe infection in early infancy. In Japan, the diphtheria-tetanus-acellular pertussis (DTaP) vaccine is available during pregnancy, whereas the tetanus-diphtheria-acellular pertussis (Tdap) vaccine is not approved. Although they share antigens, DTaP includes higher antigen levels than Tdap. Evidence on maternal DTaP immunization and antibody transfer remains limited. This study evaluated transplacental pertussis antibody transfer after maternal DTaP immunization. This single-center observational study included pregnant women who delivered at a tertiary perinatal center (May 2023 and February 2025) classified as antibody-positive (maternal PT-IgG ≥10 EU/mL), unvaccinated (PT-IgG <10 EU/mL without immunization), or vaccinated (PT-IgG <10 EU/mL with DTaP). Maternal and cord blood samples were analyzed for pertussis toxin IgG (PT-IgG) and filamentous hemagglutinin IgG (FHA-IgG). We included 240 women (80/group). Cord blood antibody positivity rates were 70%, 94%, and 14% in the antibody-positive, vaccinated, and unvaccinated groups (P<0.0001). PT-IgG titers were 14.8, 30.0, and 4.41 EU/mL, and FHA-IgG titers were 18.9, 75.3, and 9.52 EU/mL (P<0.0001). Gestational week at immunization and antibody titers were not correlated, and no serious vaccine-related adverse events occurred. Maternal DTaP immunization demonstrated efficient transplacental transfer. These findings support maternal DTaP use in Japan to enhance neonatal protection against pertussis where Tdap is unavailable.