Safety and immunogenicity of a third dose of COVID-19 protein subunit vaccine (CovovaxTM) after homologous and heterologous two-dose regimens
Sitthichai Kanokudom, Jira Chansaenroj, Nungruthai Suntronwong, Suvichada Assawakosri, Ritthideach Yorsaeng, Pornjarim Nilyanimit, Ratchadawan Aeemjinda, Nongkanok Khanarat, Preeyaporn Vichaiwattana, Sirapa Klinfueng, Thanunrat Thongmee, Apirat Katanyutanon, Wichai Thanasopon, Jirawan Arayapong, Withak Withaksabut, Donchida Srimuan, Thaksaporn Thatsanatorn, Natthinee Sudhinaraset, Nasamon Wanlapakorn, Sittisak Honsawek, Yong Poovorawan
Abstract
ObjectivesTo report the safety and immunogenicity profile of a protein subunit vaccine (CovovaxTM) given as a third (booster) dose to individuals primed with different primary vaccine regimens.MethodsA third dose was administered to individuals with an interval range of 3-10 months after the second dose. The four groups were classified according to their primary vaccine regimens, including two-dose BBIBP-CorV, AZD1222, BNT162b2, and CoronaVac/AZD1222. Immunogenicity analysis was performed to determine binding antibodies, neutralizing activity, and the T-cell responses.ResultsOverall, 210 individuals were enrolled and boosted with the CovovaxTM vaccine. The reactogenicity was mild to moderate. Most participants elicited a high level of binding and neutralizing antibody against Wild-type and Omicron variants after the booster dose. In participants who were antinucleocapsid immunoglobulin G-negative from all groups, a booster dose could elicit neutralizing activity to Wild-type and Omicron variants by more than 95% and 70% inhibition at 28 days, respectively. The CovovaxTM vaccine could elicit a cell-mediated immune response.ConclusionThe protein subunit vaccine (CovovaxTM) can be proposed as a booster dose after two different priming dose regimens. It has strong immunogenicity and good safety profiles.