{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T09:42:19Z","timestamp":1785404539490,"version":"3.56.0"},"posted":{"date-parts":[[2026,7,18]]},"group-title":"Infectious Diseases (except HIV\/AIDS)","reference-count":30,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,7,18]],"date-time":"2026-07-18T00:00:00Z","timestamp":1784332800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"award":["R21AI191038"],"award-info":[{"award-number":["R21AI191038"]}],"id":[{"id":"https:\/\/ror.org\/043z4tv69","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,7,18]]},"abstract":"<jats:label>1.<\/jats:label>\n                <jats:title>ABSTRACT<\/jats:title>\n                <jats:p>Respiratory syncytial virus (RSV) contributes to substantial morbidity and mortality in young children each year. In 2023, two new prevention products were licensed and recommended in the United States (US), including a prefusion F protein subunit vaccine (RSVpreF) administered during pregnancy and a long-acting monoclonal antibody (mAb) administered in infants.<\/jats:p>\n                <jats:p>Although post-licensure real-world studies support the effectiveness of RSVpreF vaccine during pregnancy, existing studies have been conducted in settings where only RSVpreF vaccine is available. The real-world effectiveness of RSVpreF vaccine in settings where both RSVpreF vaccine and mAbs are available is not yet well understood. The goal of this study is to estimate the real-world effectiveness of the RSVpreF vaccine against severe infant RSV by applying causal mediation analysis with receipt of mAbs as a mediating variable. Using a national cohort of mother-infant dyads with the Optum Labs Data Warehouse (OLDW), we will model vaccine and mAb effects in a longitudinal cohort spanning the 2023-24, 2024-25, and 2025-26 RSV seasons. Results will be used to better understand the total effect of RSVpreF vaccination when it is used as one component within a hybrid infant RSV prevention program.<\/jats:p>","DOI":"10.64898\/2026.07.16.26356876","type":"posted-content","created":{"date-parts":[[2026,7,18]],"date-time":"2026-07-18T15:40:13Z","timestamp":1784389213000},"source":"Crossref","is-referenced-by-count":0,"title":["CAUSAL-RSV: A study protocol for a causal mediation analysis of RSV vaccine effects in infants using real-world data"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3879-6193","authenticated-orcid":false,"given":"Annette K.","family":"Regan","sequence":"first","affiliation":[{"name":"Department of Research & Evaluation, Kaiser Permanente Southern California, 100 S. Los Robles Ave, Pasadena CA, 91101, USA"},{"name":"Department of Epidemiology, Fielding School of Public Health, UCLA, Los Angeles, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8474-4992","authenticated-orcid":false,"given":"Matthew M.","family":"Coates","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Fielding School of Public Health, UCLA, Los Angeles, USA"},{"name":"Practical Causal Inference Lab, UCLA, Los Angeles, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0856-0294","authenticated-orcid":false,"given":"Sheena G.","family":"Sullivan","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Fielding School of Public Health, UCLA, Los Angeles, USA"},{"name":"School of Clinical Sciences, Monash University, Melbourne, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0457-7689","authenticated-orcid":false,"given":"Flor M.","family":"Mu\u00f1oz","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, and Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9226-1376","authenticated-orcid":false,"given":"Stacey L.","family":"Rowe","sequence":"additional","affiliation":[{"name":"Department of Research & Evaluation, Kaiser Permanente Southern California, 100 S. 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