Effectiveness of Booster Doses of the SARS-CoV-2 Inactivated Vaccine KCONVAC against the Mutant Strains

Viruses. 2022 Sep 12;14(9):2016. doi: 10.3390/v14092016.

Abstract

As the COVID-19 epidemic progresses with the emergence of different SARS-CoV-2 variants, it is important to know the effectiveness of inactivated SARS-CoV-2 vaccines against the variants. To maximize efficiency, a third boost injection of the high-dose SARS-CoV-2 inactivated vaccine KCONVAC was selected for investigation. In addition to the ancestral strain, KCONVAC boost vaccination induced neutralizing antibodies and antigen-specific CD8 T cells to recognize several variants, including B.1.617.2 (Delta), B.1.1.529 (Omicron), B.1.1.7 (Alpha), B.1.351 (Beta), P.3, B.1.526.1 (Lota), B.1.526.2, B.1.618, and B.1.617.3. Both humoral and cellular immunity against variants were lower than those of ancestral variants but continued to increase from day 0 to day 7 to day 50 after boost vaccination. Fifty days post-boost, the KCONVAC-vaccinated CD8 T-cell level reached 1.23-, 2.59-, 2.53-, and 1.01-fold that of convalescents against ancestral, Delta, Omicron and other SARS-CoV-2 variants, respectively. Our data demonstrate the importance of KCONVAC boosters to broaden both humoral and cellular immune responses against SARS-CoV-2 variants.

Keywords: SARS-CoV-2; cellular immune responses; inactivated vaccine KCONVAC; variants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 Vaccines
  • COVID-19* / prevention & control
  • Humans
  • SARS-CoV-2 / genetics
  • Vaccines, Inactivated
  • Viral Vaccines*

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 Vaccines
  • SARS-CoV-2 inactivated vaccines
  • Vaccines, Inactivated
  • Viral Vaccines

Supplementary concepts

  • SARS-CoV-2 variants

Grants and funding

This work was supported by grants from the Natural Science Foundation of China (U1801285 and 92169102), the Fundamental Research Funds for the Central Universities (21622108), the fellowship of China Postdoctoral Science Foundation (2021M701417), the Guang Dong Basic and Applied Basic Research Foundation (2021A1515110734), and the Initial Startup Fund of Jinan University.