{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,3]],"date-time":"2026-05-03T23:52:31Z","timestamp":1777852351853,"version":"3.51.4"},"reference-count":30,"publisher":"SAGE Publications","license":[{"start":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T00:00:00Z","timestamp":1774569600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"funder":[{"name":"The Mustela Foundation"},{"name":"Fabian Thylmann"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["J Hum Lact"],"abstract":"<jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>The COVID-19-pandemic prompted global vaccination campaigns, raising important questions about vaccine-induced immune responses in lactating women and the transfer of SARS-CoV-2-specific antibodies through human milk. This study investigated the presence of SARS-CoV-2-specific IgA and IgG antibodies in breastmilk for up to 6 months following COVID-19 vaccination and booster doses with either mRNA or adenoviral vector (AVV) vaccines.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Method:<\/jats:title>\n                    <jats:p>The COVALAC-study was a prospective cohort study conducted in Belgium. Women were recruited between February and March 2021, followed for 180\u2009days post-vaccination and 28\u2009days post-booster. Breastmilk samples were collected at multiple timepoints and analyzed for IgA and IgG antibodies. Participants received either mRNA (BNT162b2, mRNA-127) or AVV (ChAdOx1 nCoV-19) vaccines. Antibody concentrations were measured using an in-house immunoassay, and analyses compared responses between vaccine types.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>Of the 115 participants, 40% received BNT162b2, 4.3% mRNA-1273, and 55.7% ChAdOx1-S as their primary vaccination. Of these, 31 participants received an mRNA booster (11 homologous, 20 heterologous boosters). IgA and IgG antibody levels were monitored pre- and post-vaccination, showing a stronger antibody response after mRNA vaccination compared to AVV, after roughly 14\u2009days (IgA receptor binding domain [RBD] 1.13 BAU\/mil; 0.61\u20131.67; IgG RBD 2.56 BAU\/mil; 0.76\u20134.71, up to 1\u2009month, for most antibodies. Both homologous and heterologous boosters further increased antibody titers (IgA RBD 0,85 BAU\/ml; 1.09\u20131.72).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion:<\/jats:title>\n                    <jats:p>COVID-19 vaccination during lactating induces SARS-CoV-2 specific IgA and IgG antibodies in human milk. Antibody levels were higher following mRNA vaccination compared to AVV vaccination, with booster doses enhancing these levels further.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1177\/08903344261428225","type":"journal-article","created":{"date-parts":[[2026,3,28]],"date-time":"2026-03-28T04:40:28Z","timestamp":1774672828000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":0,"title":["The COVALAC Study: The Impact of COVID-19 Vaccination During Lactation on SARS-CoV-2-Specific Antibodies in Human Milk\u2014A Prospective Cohort Study"],"prefix":"10.1177","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9862-422X","authenticated-orcid":false,"given":"Joke","family":"Muyldermans","sequence":"first","affiliation":[{"name":"Department of Pharmacological and Pharmaceutical Sciences (FARM), Experimental Pharmacology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Jette, Belgium"},{"name":"Midwifery Education, Department of Health, University College Brussels, Jette, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stefan","family":"Embacher","sequence":"additional","affiliation":[{"name":"Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kirsten","family":"Maertens","sequence":"additional","affiliation":[{"name":"Centre for the Evaluation of Vaccination, Vaccine &amp; Infectious Diseases Institute, University of Antwerp, Wilrijk, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sereina Annik","family":"Herzog","sequence":"additional","affiliation":[{"name":"Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3521-7712","authenticated-orcid":false,"given":"Isabelle","family":"Desombere","sequence":"additional","affiliation":[{"name":"Laboratory of Immune Response, Scientific Directorate in Humans, Sciensano, Ukkel, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephane","family":"De Craeye","sequence":"additional","affiliation":[{"name":"Laboratory of Immune Response, Scientific Directorate in Humans, Sciensano, Ukkel, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joeri","family":"Aerts","sequence":"additional","affiliation":[{"name":"Neuro-Aging &amp; Viro-Immunotherapy (NAVI), Department of Pharmaceutical Sciences (FARM), Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Jette, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7598-6976","authenticated-orcid":false,"given":"Eline","family":"Tommelein","sequence":"additional","affiliation":[{"name":"Department of Pharmacological and Pharmaceutical Sciences (FARM), Experimental Pharmacology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Jette, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[2026,3,27]]},"reference":[{"key":"e_1_3_4_2_1","doi-asserted-by":"crossref","unstructured":"Atyeo C. 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