{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T10:11:01Z","timestamp":1789035061744,"version":"build-2803163510"},"reference-count":11,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,6]],"date-time":"2026-09-06T00:00:00Z","timestamp":1788652800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100009619","name":"AMED","doi-asserted-by":"publisher","award":["JP26fk0108710"],"award-info":[{"award-number":["JP26fk0108710"]}],"id":[{"id":"10.13039\/100009619","id-type":"DOI","asserted-by":"publisher"}]},{"award":["JP26fk0108710"],"award-info":[{"award-number":["JP26fk0108710"]}],"id":[{"id":"https:\/\/ror.org\/004rtk039","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background\/Objectives: The approval of Abrysvo, a maternal bivalent respiratory syncytial virus (RSV) prefusion F (pre-F) vaccine, marked a major milestone in pediatric prophylaxis. However, real-world serological data on transplacental antibody transfer in Asian populations remains limited. This brief report evaluated serum RSV pre-F immunoglobulin G (IgG) geometric mean titers (GMTs) across three distinct Japanese cohorts. Methods: This single-center, comparative study analyzed neonates born to Abrysvo-vaccinated mothers (n = 12), neonates born to unvaccinated mothers (n = 40), and infants aged &lt;6 months hospitalized with laboratory-confirmed RSV infection (n = 18) using enzyme-linked immunosorbent assay (ELISA). Results: Neonates of vaccinated mothers exhibited significantly higher pre-F IgG GMTs (4.74; 95% CI: 4.30\u20135.18) than those of unvaccinated mothers (3.80; 95% CI: 3.50\u20134.14). Conversely, infants requiring hospitalization for RSV infection demonstrated critically low pre-F IgG GMTs (1.08; 95% CI: 0.65\u20132.15), revealing statistically significant differences across all three groups (p &lt; 0.001). Conclusions: Maternal immunization with Abrysvo significantly enhances passive humoral immunity in Japanese neonates compared to natural background immunity. Given the severe antibody deficiency observed in hospitalized infants, expanding maternal vaccination coverage is a high-priority public health strategy to mitigate the pediatric RSV burden in the post-pandemic era.<\/jats:p>","DOI":"10.3390\/vaccines14090780","type":"journal-article","created":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T12:12:25Z","timestamp":1788783145000},"page":"780","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Evaluation of Respiratory Syncytial Virus Prefusion F IgG Antibodies in Japanese Mother\u2013Infant Pairs Following Maternal Abrysvo Vaccination and in Infants Hospitalized with RSV Infection"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3842-3044","authenticated-orcid":false,"given":"Tomohiro","family":"Oishi","sequence":"first","affiliation":[{"name":"Department of Clinical Infectious Diseases, Kawasaki Medical School, 577, Matsushima, Kurashiki 701-0192, Okayama, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takashi","family":"Nakano","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Kawasaki Medical School, 577, Matsushima, Kurashiki 701-0192, Okayama, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1451","DOI":"10.1056\/NEJMoa2216480","article-title":"Bivalent prefusion F vaccine in pregnancy to prevent RSV illness in infants","volume":"388","author":"Kampmann","year":"2023","journal-title":"N. Engl. J. Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"946","DOI":"10.1016\/S0140-6736(17)30938-8","article-title":"Global, regional, and national disease burden estimates of acute lower respiratory tract infections due to respiratory syncytial virus in young children in 2015: A systematic review and modelling study","volume":"390","author":"Shi","year":"2017","journal-title":"Lancet"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"418","DOI":"10.1016\/j.idnow.2021.05.004","article-title":"Pediatric Infectious Disease Group (GPIP) position paper on the immune debt of the COVID-19 pandemic in childhood: How can we fill the immunity gap?","volume":"51","author":"Cohen","year":"2021","journal-title":"Infect. Dis. Now"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"168","DOI":"10.7883\/yoken.JJID.2025.119","article-title":"Ongoing shift toward earlier RSV season in children: The case of Saitama after the COVID-19 pandemic","volume":"79","author":"Fujii","year":"2026","journal-title":"Jpn. J. Infect. Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2077","DOI":"10.1093\/infdis\/jiab505","article-title":"Safety and immunogenicity of a respiratory syncytial virus prefusion F vaccine in pregnant individuals and their infants","volume":"225","author":"Peterson","year":"2022","journal-title":"J. Infect. Dis."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1665","DOI":"10.1007\/s40121-024-01000-6","article-title":"Cost-effectiveness analysis of maternal respiratory syncytial virus vaccine in protecting infants from RSV infection in Japan","volume":"13","author":"Ishiwada","year":"2024","journal-title":"Infect. Dis. Ther."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Lee, G., Hyun, J., Jang, A.Y., Choi, Y.J., Nham, E., Yoon, J.G., Choi, M.J., Noh, J.Y., Cheong, H.J., and Song, J.Y. (2026). Limited protective immunity to respiratory syncytial virus and pertussis among adults and healthcare workers in South Korea: A seroepidemiologic study. Hum. Vaccines Immunother., 22.","DOI":"10.1080\/21645515.2026.2650846"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Kachikis, A.B., Rumfelt, K., Pike, M., Sosa, M., Stolarczuk, J.E., Cho, H., Eckert, L.O., Martin, E.T., and Englund, J.A. (2024). Transfer of respiratory syncytial virus prefusion F protein antibody in high-risk and low birthweight infants. Open Forum Infect. Dis., 11.","DOI":"10.1093\/ofid\/ofae314"},{"key":"ref_9","first-page":"543","article-title":"Risk of primary respiratory syncytial virus infection and associated febrile illness in infants","volume":"140","author":"Glezen","year":"1986","journal-title":"Am. J. Dis. Child."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Palmeira, P., Quinello, C., Silveira-Lessa, A.L., Zago, C.A., and Carneiro-Sampaio, M. (2012). IgG placental transfer in healthy and pathological pregnancies. J. Immunol. Res., 2012.","DOI":"10.1155\/2012\/985646"},{"key":"ref_11","first-page":"715","article-title":"Enhanced placental antibody transfer efficiency with longer duration between maternal RSV vaccination and delivery","volume":"232","author":"Gurtman","year":"2025","journal-title":"Am. J. Obstet. Gynecol."}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/9\/780\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T09:37:32Z","timestamp":1789033052000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/9\/780"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,6]]},"references-count":11,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["vaccines14090780"],"URL":"https:\/\/doi.org\/10.3390\/vaccines14090780","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,6]]}}}