Human Vaccines & Immunotherapeutics (Jan 2023)

Immunogenicity and safety of single booster dose of KD-414 inactivated COVID-19 vaccine in adults: An open-label, single-center, non-randomized, controlled study in Japan

  • Junko Terada-Hirashima,
  • Yuki Takamatsu,
  • Yosuke Shimizu,
  • Yukari Uemura,
  • Junko S. Takeuchi,
  • Noriko Tomita,
  • Kouki Matsuda,
  • Kenji Maeda,
  • Shohei Yamamoto,
  • Ami Fukunaga,
  • Norio Ohmagari,
  • Ayako Mikami,
  • Kengo Sonoda,
  • Mugen Ujiie,
  • Hiroaki Mitsuya,
  • Wataru Sugiura

DOI
https://doi.org/10.1080/21645515.2023.2193074
Journal volume & issue
Vol. 19, no. 1

Abstract

Read online

Although vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease 2019 (COVID-19) induce effective immune responses, vaccination with booster doses is necessary because of waning immunity. We conducted an open-label, non-randomized, single-arm study in adults in Japan to assess the immunogenicity and safety of a single booster dose of the KD-414 purified whole-SARS-CoV-2-virion inactivated vaccine candidate after vaccination with a primary series of BNT162b2. The primary endpoint was serum neutralizing activity at 7 days after booster injection compared with the primary series of BNT162b2. The SARS-CoV-2-structural protein-binding antibody level and T cell response against SARS-CoV-2-Spike (S) peptides were also examined as secondary endpoints, and safety profile assessments were conducted. Twenty subjects who participated in a previous study declined an injection of KD-414 (non-KD-414 group) and received a booster dose of BNT162b2 instead. The non-KD-414 group was compared to the KD-414 group as a secondary outcome. A single dose of KD-414 induced lower serum neutralizing activity against the wild-type virus within 7 days compared to after the primary series of BNT162b2 but significantly induced anti-SARS-CoV-2-S1-receptor-binding domain-binding immunoglobulin G (IgG) antibodies and SARS-CoV-2-S peptide-specific CD4+ and CD8+ T cell responses. Local or systemic symptoms were significantly lower in the participants who received KD-414 than in those who received BNT162b2 as the third COVID-19 vaccine dose. The present data indicate that a single booster dose of KD-414 induces a substantial immune response in BNT162b2-primed individuals and has a good safety profile, thereby supporting further clinical trials to identify rational targets.

Keywords