Abstract
In light of intermittent supply shortages of individual vaccines and evidence of rare but serious adverse events after vaccination, heterologous regimens for COVID-19 vaccines have gained significant interest. This study aims to assess the reactogenicity and immunogenicity of the heterologous adenoviral vector (ChAdOx1-S, AstraZeneca; hereafter referred to as AZ) and the inactivated vaccine regimen (CoronaVac; hereafter referred to as CV) in healthy Thai adults immunized between June and September 2021. Our study showed that adverse events following homologous CV-CV and AZ-AZ, and heterologous CV-AZ and AZ-CV combinations, were mild and well tolerated overall. Receptor-binding domain (RBD)-specific antibody responses and neutralizing activities against wild-type and variants of concern after two-dose vaccination were higher in the heterologous CV-AZ and homologous AZ-AZ groups compared to the CV-CV and AZ-CV groups. Conversely, the spike-specific IgA response was detected only in the CV-AZ group after two doses of vaccination. The total interferon gamma response was detected in both the CV-AZ and AZ-CV groups after the two-dose vaccination. Given the shorter completion time of two doses, heterologous CoronaVac followed by ChAdOx1-S can be considered as an alternative regimen to homologous efficacy-proven ChAdOx1-S in countries with circulating variants. Additional studies on the efficacy and durability of immune responses induced by heterologous vaccine regimens are warranted.
Keywords: COVID-19; Heterologous; adults; homologous; inactivated; vaccine; viral vectored.
【저자키워드】 COVID-19, Vaccine, Adults, homologous, Heterologous, inactivated, viral vectored., 【초록키워드】 Efficacy, COVID-19 vaccine, immune response, vaccination, immunogenicity, reactogenicity, Antibody Response, CoronaVac, variants of concern, variants, adverse events, Neutralizing activity, COVID-19 vaccines, Viral, Receptor-binding domain, Inactivated vaccine, immune responses, adverse event, Mild, group, ChAdOx1, AstraZeneca, ChAdOx1-S, interferon gamma, Evidence, dose, heterologous vaccine, regimen, supply shortage, evidence of, referred to, followed by, Serious Adverse Events, Serious Adverse Event, combinations, wild-type, neutralizing activities, doses, IgA response, circulating variants, country, immunized, heterologous adenoviral vector, healthy, groups, 【제목키워드】 COVID-19 vaccine, Safety, prospective cohort study, regimen, healthy,