Immunogenicity of Abdala COVID-19 vaccine in Vietnamese people after primary and booster vaccinations: a prospective observational study in Vietnam.
Thanh TT., Tu NTK., Nguyet LA., Thuy CT., Thuan NLT., Ny NTH., Nhu LNT., Thanh LK., Hong NTT., Anh NT., Truong NT., Chau NVV., Yen LM., Van E P., Thuong NP., Van Truc N., Trung PH., Yap WC., Pandey R., Yee S., Weng R., Mongkolsapaya J., Dejnirattisai W., Hamers RL., Chantratita N., Screaton G., Dunachie SJ., Jones EY., Stuart DI., Dung NT., Thwaites G., Wang L-F., Tan CW., Van Tan L., SECOVARIANTS and ASSeSS Consortia None.
OBJECTIVES: We studied the immunogenicity after primary and booster vaccinations of Abdala COVID-19 vaccine, a receptor binding domain protein subunit vaccine, in Vietnamese people by determining the level of neutralization and cross-neutralization activities against the ancestral SARS-CoV-2 and its variants, and SARS-CoV-1. METHODS: We performed a prospective observational study, enrolling adults aged 19-59 years in Dong Thap province, southern Vietnam, and collected blood samples from baseline until 4 weeks post booster dose. We measured anti-nucleocapsid, anti-spike and neutralizing antibodies against SARS-CoV-2, and assessed the cross-neutralization against 14 SARS-CoV-2 variants, and SARS-CoV-1. Complementary antibody data came from Vietnamese healthcare workers fully vaccinated with ChAdOx1-S. RESULTS: After primary vaccination, anti-spike antibody and neutralizing antibodies were detectable in 98.4% and 87% of 251 study participants, respectively, with neutralizing antibody titers similar to that induced by ChAdOx1-S vaccine. Antibody responses after a homologous (Abdala COVID-19) or heterologous (mRNA BNT162b2) booster could neutralize 14 SARS-CoV-2 variants (including Omicron), and SARS-CoV-1. CONCLUSIONS: Abdala COVID-19 vaccine is immunogenic in Vietnamese people. Enhanced antibody response after a booster dose could cross-neutralize 14 SARS-CoV-2 variants and SARS-CoV-1. Our results have added to the growing body of knowledge about the contribution of protein subunit vaccine platforms to pandemic control.