Vaccines (Aug 2023)

Immunogenicity of Mix-and-Match CoronaVac/BNT162b2 Regimen versus Homologous CoronaVac/CoronaVac Vaccination: A Single-Blinded, Randomized, Parallel Group Superiority Trial

  • Samar Samoud,
  • Jihene Bettaieb,
  • Mariem Gdoura,
  • Ghassen Kharroubi,
  • Feriel Ben Ghachem,
  • Imen Zamali,
  • Ahlem Ben Hmid,
  • Sadok Salem,
  • Ahmed Adel Gereisha,
  • Mongi Dellagi,
  • Nahed Hogga,
  • Adel Gharbi,
  • Amor Baccouche,
  • Manel Gharbi,
  • Chadha Khemissi,
  • Ghada Akili,
  • Wissem Slama,
  • Nabila Chaieb,
  • Yousr Galai,
  • Hechmi Louzir,
  • Henda Triki,
  • Melika Ben Ahmed

DOI
https://doi.org/10.3390/vaccines11081329
Journal volume & issue
Vol. 11, no. 8
p. 1329

Abstract

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(1) Background: This study aimed to compare the immunogenicity of the mix-and-match CoronaVac/BNT162b2 vaccination to the homologous CoronaVac/CoronaVac regimen. (2) Methods: We conducted a simple-blinded randomized superiority trial to measure SARS-CoV-2 neutralization antibodies and anti-spike receptor binding domain (RBD) IgG concentrations in blood samples of participants who had received the first dose of CoronaVac vaccine followed by a dose of BNT162b2 or CoronaVac vaccine. The primary endpoint for immunogenicity was the serum-neutralizing antibody level with a percentage of inhibition at 90% at 21–35 days after the boost. A difference of 25% between groups was considered clinically relevant. (3) Results: Among the 240 eligible participants, the primary endpoint data were available for 100 participants randomly allocated to the mix-and-match group versus 99 participants randomly allocated to the homologous dose group. The mix-and-match regimen elicited significantly higher levels of neutralizing antibodies (median level of 96%, interquartile range (IQR) (95–97) versus median level of 94%, IQR (81–96) and anti-spike IgG antibodies (median level of 13,460, IQR (2557–29,930) versus median level of 1190, IQR (347–4964) compared to the homologous group. Accordingly, the percentage of subjects with a percentage of neutralizing antibodies > 90% was significantly higher in the mix-and-match group (90.0%) versus the homologous (60.6%). Interestingly, no severe events were reported within 30 days after the second dose of vaccination in both groups. (4) Conclusions: Our data showed the superiority of the mix-and-match CoronaVac/BNT162b2 vaccination compared to the CoronaVac/CoronaVac regimen in terms of immunogenicity, thus constituting a proof-of-concept study supporting the use of inactivated vaccines in a mix-and-match strategy while ensuring good immunogenicity and safety.

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