A three-dose mRNA COVID-19 vaccine regime produces both suitable immunogenicity and satisfactory efficacy in patients with solid cancersJanžič, Urška (Avtor) Bidovec, Urška (Avtor) Korošec, Peter (Avtor) Mohorčič, Katja (Avtor) Mrak, Loredana (Avtor) Čakš, Marina (Avtor) Ravnik, Maja (Avtor) Škof, Erik (Avtor) Rijavec, Matija (Avtor) solid cancerCOVID-19 vaccinationbooster third doseBackground: The recommended booster third dose of vaccination against COVID-19 in cancer patients seems reasonable to protect them against a severe disease course. A prospective study was designed to assess the immunogenicity, efficacy, and safety of COVID-19 vaccination in this cohort. Methods: Patients with solid malignancies on active treatment were followed up after the primary course and booster third dose of vaccination to assess their anti-SARS-CoV-2 S1 IgG levels, efficacy in the case of SARS-CoV-2 infection, and safety. Results: Out of 125 patients receiving the primary course of vaccination, 66 patients received a booster third dose of mRNA vaccine, with a 20-fold increase in median anti-SARS-CoV-2 S1 IgG levels compared to Ab levels six months post-primary course of vaccination (p < 0.0001). After the booster third dose, anti-SARS-CoV-2 S1 IgG levels were comparable to healthy controls (p = 0.113). There was a decline in Ab levels 3 (p = 0.0003) and 6 months (p < 0.0001) post-third booster dose. No patients had either a severe disease course or a lethal outcome in the case of SARS-CoV-2 infection after the third booster dose. Conclusion: The third booster vaccination dose against COVID-19 in solid cancer patients triggers substantial immunogenicity and is safe and effective for preventing a severe COVID-19 disease course.MDPI AG, 2013- 20232026-02-25 09:09:18Neznano27793Vaccinessl© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).