Comparison of safety and immunogenicity of CoronaVac and ChAdOx1 against the SARS-CoV-2 circulating variants of concern (Alpha, Delta, Beta) in Thai healthcare workers

Nasikarn Angkasekwinai; Jaturong Sewatanon; Suvimol Niyomnaitham; Supaporn Phumiamorn; Kasama Sukapirom; Sompong Sapsutthipas; Rujipas Sirijatuphat; Orasri Wittawatmongkol; Sansnee Senawong; Surakameth Mahasirimongkol; Sakalin Trisiriwanich; Kulkanya Chokephaibulkit

doi:10.1016/j.jvacx.2022.100153

Comparison of safety and immunogenicity of CoronaVac and ChAdOx1 against the SARS-CoV-2 circulating variants of concern (Alpha, Delta, Beta) in Thai healthcare workers

Vaccine X. 2022 Mar 5:10:100153. doi: 10.1016/j.jvacx.2022.100153. eCollection 2022 Apr.

Authors

Affiliations

¹ Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.
² Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.
³ Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.
⁴ Siriraj Institute of Clinical Research (SICRES), Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.
⁵ Department of Medical Sciences, Ministry of Public Health, Thailand.
⁶ Biomedical Research Incubator Unit, Department of Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.
⁷ Siriraj Center of Research Excellence in Microparticle and Exosome in Disease, Thailand.
⁸ Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.
⁹ Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.

Abstract

Background: Inactivated vaccine (CoronaVac) and chimpanzee adenovirus-vector vaccine (ChAdOx1) have been widely used in resource-limited settings. However, the information on the reactogenicity and immunogenicity of these two vaccines in the same setting are limited.

Methods: Healthy health care workers (HCWs) aged 18 years or older were randomly assigned to receive either two doses of CoronaVac at 4 weeks interval or two doses of ChAdOx1 at 10 weeks interval. Self-reported adverse events (AEs) were collected for 7 days following each vaccination. Immunogenicity was determined by IgG antibodies levels against receptor binding domain (RBD) of the SARS-CoV-2 spike protein (S1 subunit) and the 50% plaque reduction neutralization titers against various strains.

Results: Of the 360 HCWs, 180 in each vaccine group, the median (interquartile range: IQR) age was 35 (29-44) years old and 84.2% were female. Participants who received ChAdOx1 reported higher frequency of AEs than those received CoronaVac after both the first dose (84.4% vs. 66.1%, P < 0.001) and second dose (75.6% vs. 60.6%, P = 0.002), with more AEs in those younger than 30 years of age for both vaccines. The seroconversion rates were 75.6% and 100% following the first dose of CoronaVac and ChAdOx1, respectively. All participants were seropositive at 2 weeks after the second dose. The anti-SARS-CoV-2 RBD IgG levels induced by CoronaVac was lower than ChAdOX1 with geometric means of 164.4 and 278.5 BAU/mL, respectively (P = 0.0066). Both vaccines induced similar levels of neutralizing antibodies against the Wuhan strain, with the titers of 337.4 and 331.2; however, CoronaVac induced significantly lower GMT against Alpha (23.1 vs. 92.5), Delta (21.2 vs. 69.7), and Beta (10.2 vs. 43.6) variants, respectively.

Conclusion: CoronaVac induces lower measurable antibodies against circulating variants but with lower frequency of AEs than ChAdOx1. An earlier boosting to prevent breakthrough infections may be needed.

Keywords: ChAdOx1; CoronVac; Heath care workers; Immunogenicity; Thailand; Variant of concern.