The Third dose of CoronVac vaccination induces broad and potent adaptive immune responses that recognize SARS-CoV-2 Delta and Omicron variants

• Published in: Emerging microbes & infections Vol. 11; no. 1; pp. 1524 - 1536
• Main Authors: Chen, Yuxin, Chen, Lin, Yin, Shengxia, Tao, Yue, Zhu, Liguo, Tong, Xin, Mao, Minxin, Li, Ming, Wan, Yawen, Ni, Jun, Ji, Xiaoyun, Dong, Xianchi, Li, Jie, Huang, Rui, Shen, Ya, Shen, Han, Bao, Changjun, Wu, Chao
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01.12.2022; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: Antibodies, Neutralizing; Antibodies, Viral; booster; CD8-Positive T-Lymphocytes; coronavac; Coronaviruses; COVID-19 - prevention & control; COVID-19 vaccine; COVID-19 Vaccines; Humans; Immune response; Immunity, Humoral; Lymphocytes; neutralization; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; T cell responses; Vaccination; COVID-19 vaccine; coronavac; neutralization; booster; T cell responses
• ISSN: 2222-1751; 2222-1751
• DOI: 10.1080/22221751.2022.2081614

The waning humoral immunity and emerging contagious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants resulted in the necessity of the booster vaccination of coronavirus disease 2019 (COVID-19). The inactivated vaccine, CoronaVac, is the most widely supplied COVID-19 vaccine globally. Whether the CoronaVac booster elicited adaptive responses that cross-recognize SARS-CoV-2 variants of concern (VoCs) among 77 healthy subjects receiving the third dose of CoronaVac were explored. After the boost, remarkable elevated spike-specific IgG and IgA responses, as well as boosted neutralization activities, were observed, despite 3.0-fold and 5.9-fold reduced neutralization activities against Delta and Omicron strains compared to that of the ancestral strain. Furthermore, the booster dose induced potent B cells and memory B cells that cross-bound receptor-binding domain (RBD) proteins derived from VoCs, while Delta and Omicron RBD-specific memory B cell recognitions were reduced by 2.7-fold and 4.2-fold compared to that of ancestral strain, respectively. Consistently, spike-specific circulating follicular helper T cells (cTfh) significantly increased and remained stable after the boost, with a predominant expansion towards cTfh17 subpopulations. Moreover, SARS-CoV-2-specific CD4 + and CD8 + T cells peaked and sustained after the booster. Notably, CD4 + and CD8 + T cell recognition of VoC spike was largely preserved compared to the ancestral strain. Individuals without generating Delta or Omicron neutralization activities had comparable levels of CD4 + and CD8 + T cells responses as those with detectable neutralizing activities. Our study demonstrated that the CoronaVac booster induced broad and potent adaptive immune responses that could be effective in controlling SARS-CoV-2 Delta and Omicron variants.