Signal Transduction and Targeted Therapy (Feb 2024)

Safety, immunogenicity and protective effectiveness of heterologous boost with a recombinant COVID-19 vaccine (Sf9 cells) in adult recipients of inactivated vaccines

  • Wenxin Luo,
  • Jiadi Gan,
  • Zhu Luo,
  • Shuangqing Li,
  • Zhoufeng Wang,
  • Jiaxuan Wu,
  • Huohuo Zhang,
  • Jinghong Xian,
  • Ruixin Cheng,
  • Xiumei Tang,
  • Yi Liu,
  • Ling Yang,
  • Qianqian Mou,
  • Xue Zhang,
  • Yi Chen,
  • Weiwen Wang,
  • Yantong Wang,
  • Lin Bai,
  • Xuan Wei,
  • Rui Zhang,
  • Lan Yang,
  • Yaxin Chen,
  • Li Yang,
  • Yalun Li,
  • Dan Liu,
  • Weimin Li,
  • Lei Chen

DOI
https://doi.org/10.1038/s41392-024-01751-1
Journal volume & issue
Vol. 9, no. 1
pp. 1 – 9

Abstract

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Abstract Vaccines have proven effective in protecting populations against COVID-19, including the recombinant COVID-19 vaccine (Sf9 cells), the first approved recombinant protein vaccine in China. In this positive-controlled trial with 85 adult participants (Sf9 cells group: n = 44; CoronaVac group: n = 41), we evaluated the safety, immunogenicity, and protective effectiveness of a heterologous boost with the Sf9 cells vaccine in adults who had been vaccinated with the inactivated vaccine, and found a post-booster adverse events rate of 20.45% in the Sf9 cells group and 31.71% in the CoronaVac group (p = 0.279), within 28 days after booster injection. Neither group reported any severe adverse events. Following the Sf9 cells vaccine booster, the geometric mean titer (GMT) of binding antibodies to the receptor-binding domain of prototype SARS-CoV-2 on day 28 post-booster was significantly higher than that induced by the CoronaVac vaccine booster (100,683.37 vs. 9,451.69, p < 0.001). In the Sf9 cells group, GMTs of neutralizing antibodies against pseudo SARS-CoV-2 viruses (prototype and diverse variants of concern [VOCs]) increased by 22.23–75.93 folds from baseline to day 28 post-booster, while the CoronaVac group showed increases of only 3.29–10.70 folds. Similarly, neutralizing antibodies against live SARS-CoV-2 viruses (prototype and diverse VOCs) increased by 68.18–192.67 folds on day 14 post-booster compared with the baseline level, significantly greater than the CoronaVac group (19.67–37.67 folds). A more robust Th1 cellular response was observed with the Sf9 cells booster on day 14 post-booster (mean IFN-γ+ spot-forming cells per 2 × 105 peripheral blood mononuclear cells: 26.66 vs. 13.59). Protective effectiveness against symptomatic COVID-19 was approximately twice as high in the Sf9 cells group compared to the CoronaVac group (68.18% vs. 36.59%, p = 0.004). Our study findings support the high protective effectiveness of heterologous boosting with the recombinant COVID-19 vaccine (Sf9 cells) against symptomatic COVID-19 of diverse SARS-CoV-2 variants of concern, while causing no apparent safety concerns.