{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T10:02:14Z","timestamp":1772704934108,"version":"3.50.1"},"reference-count":0,"publisher":"South African Medical Association NPC","license":[{"start":{"date-parts":[[2025,9,2]],"date-time":"2025-09-02T00:00:00Z","timestamp":1756771200000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["S Afr Med J"],"abstract":"<jats:p>Background. Rapid COVID\u201019 vaccine development occurred during the pandemic and vaccine\u2010related complications such as thrombosis with thrombocytopenia syndrome were discovered. Clinical trials and treating facilities included D\u2010dimer testing in COVID\u201019 vaccine trials and COVID\u201019 disease\u2010severity assessments, respectively. D\u2010dimer testing and result interpretation is complex and its use in isolation is controversial.\nObjectives. To evaluate D\u2010dimer levels in healthy adult participants regardless of HIV status, prior to and 2 weeks after receipt of fractional and full\u2010dose Ad26.COV2.S or Comirnaty booster COVID\u201019 vaccination, after a full dose Ad26.COV2.S prime, stratified by booster vaccination arm, age and HIV status.\nMethods. BaSiS, a prospective open\u2010label trial, enrolled 289 healthy adults. Participants with controlled comorbidities, HIV infection with no immunological or virological exclusions, and no prior thrombosis enrolled at four sites in South Africa (SA). Participants previously received a single Ad26.COV2.S prime vaccination through the Sisonke phase IIIB open\u2010label implementation study or the COVID\u201019 vaccine programme in SA. Participants were randomised 1:1:1:1 to receive one of four boosters: full\u2010dose Ad26.COV2.S, half\u2010dose Ad26.COV2.S, full\u2010dose Comirnaty or half\u2010dose Comirnaty. D\u2010dimer testing (INNOVANCE D\u2010dimer assay), as a coagulopathy marker, was conducted before the booster (baseline) and 2 weeks after the booster. The primary objectives previously reported included safety and immunogenicity of booster vaccination and fractional dosing with Ad26.COV2.S or Comirnaty in Ad26.COV2.S\u2010vaccinated participants. An exploratory objective evaluating clotting profiles, measured by D\u2010dimers, is reported here.\nResults. The median age among 285 evaluable participants included in this analysis was 42.2 (interquartile range (IQR): 35.5 \u2010 48.7) years; 82.5% (235\/285) were female and 94.4% (269\/285) were black African. Of the 40.4% (115\/285) of people living with HIV, 79.1% (91\/115) were well controlled on antiretroviral therapy. At baseline, 39.3% (112\/285) of participants had elevated D\u2010dimer levels \u2012 all asymptomatic. Females and obese participants were significantly more likely to have elevated baseline D\u2010dimer levels (adjusted odds ratio (aOR): 3.14, 95% confidence interval (CI): 1.32 \u2010 7.48 and aOR: 2.20, 95% CI: 1.22 \u2010 3.96, respectively). Of 276 participants with D\u2010dimer results available at 2 weeks after the booster, 109 (39.5%) had elevated D\u2010dimer levels. Those with elevated levels at baseline and female participants (aOR: 14.75, 95% CI: 7.64 \u2010 28.48 and aOR: 3.24, 95% CI: 1.14 \u2010 9.22, respectively) were significantly more likely to have elevated D\u2010dimer levels at 2 weeks.\nConclusion. Elevated D\u2010dimer levels in asymptomatic, low\u2010risk adults were unexpectedly common and not associated with thromboembolism. This supports the rationale of including D\u2010dimer testing in conjunction with other coagulopathy markers, only if clinically indicated in both COVID\u201019 vaccine clinical trials and the general population.<\/jats:p>","DOI":"10.7196\/samj.2025.v115i8.3121","type":"journal-article","created":{"date-parts":[[2025,9,2]],"date-time":"2025-09-02T14:39:11Z","timestamp":1756823951000},"page":"e3121","source":"Crossref","is-referenced-by-count":0,"title":["Clot twist \u2013 D-dimer analysis of healthy adults receiving heterologous or homologous booster COVID-19 vaccine after a single prime dose of Ad26.COV2.S in a phase II randomised open-label trial, BaSiS"],"prefix":"10.7196","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1503-2016","authenticated-orcid":false,"given":"F","family":"Patel","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-7229-3031","authenticated-orcid":false,"given":"J","family":"Le Roux","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3845-4863","authenticated-orcid":false,"given":"S","family":"Sawry","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"R","family":"Kieser","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9353-4295","authenticated-orcid":false,"given":"M","family":"Dhar","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"K","family":"Gill","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"E","family":"Lazarus","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A","family":"Nana","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"N","family":"Garrett","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"P L","family":"Moore","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A","family":"Sigal","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"G","family":"Gray","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1442-6734","authenticated-orcid":false,"given":"H V","family":"Rees","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"B F","family":"Jacobson","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5327-1734","authenticated-orcid":false,"given":"L","family":"Fairlie","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"4425","published-online":{"date-parts":[[2025,9,2]]},"container-title":["South African Medical Journal"],"original-title":[],"link":[{"URL":"https:\/\/samajournals.co.za\/index.php\/samj\/article\/download\/3121\/1505","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/samajournals.co.za\/index.php\/samj\/article\/download\/3121\/1505","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T09:06:53Z","timestamp":1772701613000},"score":1,"resource":{"primary":{"URL":"https:\/\/samajournals.co.za\/index.php\/samj\/article\/view\/3121"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,2]]},"references-count":0,"URL":"https:\/\/doi.org\/10.7196\/samj.2025.v115i8.3121","relation":{},"ISSN":["2078-5135","0256-9574"],"issn-type":[{"value":"2078-5135","type":"electronic"},{"value":"0256-9574","type":"print"}],"subject":[],"published":{"date-parts":[[2025,9,2]]}}}