{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T07:03:39Z","timestamp":1790060619648,"version":"4.0.1"},"reference-count":28,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T00:00:00Z","timestamp":1787529600000},"content-version":"vor","delay-in-days":23,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T00:00:00Z","timestamp":1785542400000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Eur J Immunol"],"published-print":{"date-parts":[[2026,8]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>Correlates of protection against symptomatic and severe breakthrough SARS\u2010CoV\u20102 infections are well characterized. However, correlates of protection against virus transmission are poorly defined due to a lack of evidence in well\u2010designed prospective clinical trials. We studied a Croatian cohort of individuals with documented household exposure to SARS\u2010CoV\u20102 in late 2022\/early 2023. Sera were acquired at the time of the COVID\u201019 diagnosis of the index case and before symptom onset of the test case. Samples were comprehensively analyzed for predictors of protection against virus transmission. PCR\u2010negative participants at day 0 were recalled 14 days later and re\u2010tested by PCR and IgM ELISA to identify any virus transmission, including asymptomatic ones. Out of nearly 200 tested serological parameters, several serological features differed between the participants that became PCR\u2010positive during the study period and those that remained PCR\u2010negative, although none remained significant after correction for multiple testing in the full cohort. Titers of variant\u2010specific neutralizing antibody showed the biggest difference and were higher in the uninfected subgroup. Since recent antigenic exposure may confound results, we identified the recipients exhibiting IgM seroconversion and censored them from the study. This refinement clearly separated infected and uninfected individuals by variant\u2010specific neutralization titers and IgA1 responses to BA4\/5 RBD, which remained significant after correction. Therefore, our data indicate that high IgA1 and neutralizing titers may be predictive serum correlates of protection against SARS\u2010CoV\u20102 transmission in intense contacts among household members, but only if variant\u2010specific antigen is used in serological assays.<\/jats:p>","DOI":"10.1002\/eji.70269","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T12:53:03Z","timestamp":1787575983000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Serological Predictors of Protection from Infection Upon Household Exposure to SARS\u2010CoV\u20102"],"prefix":"10.1002","volume":"56","author":[{"given":"Henrike","family":"Maa\u00df","sequence":"first","affiliation":[{"name":"Department of Viral Immunology Helmholtz Center for Infection Research  Braunschweig Germany"},{"name":"Centre For Individualised Infection Medicine (CiiM) a joint venture of Helmholtz Centre for Infection Research and Hannover Medical School  Hannover Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Imke","family":"Hinrichs","sequence":"additional","affiliation":[{"name":"Laboratory of Anti\u2010Viral Antibody\u2010Omics, TWINCORE\u2010Institute for Experimental Infection Research Helmholtz Center for Infection Research (HZI) and Medical School Hannover (MHH)  Hannover Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martina","family":"Pavletic","sequence":"additional","affiliation":[{"name":"Emergency Department Clinical Hospital Center Rijeka  Rijeka Croatia"},{"name":"Department for Anesthesiology and Reanimatology Emergency and Intensive Care Medicine, Medical Faculty Rijeka  Rijeka Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manuela","family":"Harries","sequence":"additional","affiliation":[{"name":"Department of Epidemiology Helmholtz Center for Infection Research  Braunschweig Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tatjana","family":"Prinke","sequence":"additional","affiliation":[{"name":"Department of Viral Immunology Helmholtz Center for Infection Research  Braunschweig Germany"},{"name":"Centre For Individualised Infection Medicine (CiiM) a joint venture of Helmholtz Centre for Infection Research and Hannover Medical School  Hannover Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Najat","family":"Bdeir","sequence":"additional","affiliation":[{"name":"Department of Viral Immunology Helmholtz Center for Infection Research  Braunschweig Germany"},{"name":"Centre For Individualised Infection Medicine (CiiM) a joint venture of Helmholtz Centre for Infection Research and Hannover Medical School  Hannover Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard","family":"Egelkamp","sequence":"additional","affiliation":[{"name":"Public Health Agency of Lower Saxony (NLGA)  Hannover Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Berit","family":"Lange","sequence":"additional","affiliation":[{"name":"Department of Epidemiology Helmholtz Center for Infection Research  Braunschweig Germany"},{"name":"German Centre for Infection Research (DZIF) Partner Site Hannover\/Braunschweig  Braunschweig Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yannic C.","family":"Bartsch","sequence":"additional","affiliation":[{"name":"Laboratory of Anti\u2010Viral Antibody\u2010Omics, TWINCORE\u2010Institute for Experimental Infection Research Helmholtz Center for Infection Research (HZI) and Medical School Hannover (MHH)  Hannover Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mate","family":"Lerga","sequence":"additional","affiliation":[{"name":"Emergency Department Clinical Hospital Center Rijeka  Rijeka Croatia"},{"name":"Department for Anesthesiology and Reanimatology Emergency and Intensive Care Medicine, Medical Faculty Rijeka  Rijeka Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luka","family":"Cicin\u2010Sain","sequence":"additional","affiliation":[{"name":"Department of Viral Immunology Helmholtz Center for Infection Research  Braunschweig Germany"},{"name":"Centre For Individualised Infection Medicine (CiiM) a joint venture of Helmholtz Centre for Infection Research and Hannover Medical School  Hannover Germany"},{"name":"German Centre for Infection Research (DZIF) Partner Site Hannover\/Braunschweig  Braunschweig Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,8,24]]},"reference":[{"issue":"7","key":"e_1_2_9_2_1","first-page":"28","article-title":"Long COVID: Long\u2010Term Impact of SARS\u2010CoV\u20102","volume":"14","author":"Makhluf H.","year":"2024","journal-title":"Diagnostics 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