Safety and immunogenicity of Thailand Government Pharmaceutical Organization (GPO) produced, COVID-19 vaccine, 10 μg HXP-GPOVac: A Phase III, double-blind, randomized trial in comparison with VAXZEVRIA.
Kriengkrai Prasert, Sutthichai Nakphook, Jiraphut Kittiwatanachod et al.
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In 30 seconds
This phase III, double-blind, randomized active-controlled trial compared a single dose of Thailand-produced HXP-GPOVac with VAXZEVRIA in healthy or clinically stable Thai adults who had completed a two-dose COVID-19 vaccine primary series. Among 4,000 participants, solicited adverse events were reported by 43.7% of HXP-GPOVac recipients and 53.5% of VAXZEVRIA recipients; most were mild, and no vaccine-related serious adverse events were reported. At day 14, HXP-GPOVac met prespecified non-inferiority criteria for neutralizing antibody responses and seroconversion.
Key findings
- Solicited adverse events occurred in 43.7% with HXP-GPOVac versus 53.5% with VAXZEVRIA (p = 0.01); most were mild.
- No vaccine-related serious adverse events were reported.
- At day 14, the neutralizing antibody GMC ratio was 0.83 (95% CI lower bound: 0.74), meeting the prespecified non-inferiority criterion.
- The day-14 seroconversion rate difference was -2.35% (95% CI lower bound: -8.72%), also meeting non-inferiority criteria.
Why it matters
The trial provides comparative safety and short-term immunogenicity data for a locally produced vaccine in adults previously vaccinated against COVID-19. Demonstrating non-inferior antibody responses against an authorized comparator supports further evaluation of HXP-GPOVac, while the study does not establish its clinical efficacy in preventing COVID-19.
What to keep in mind
The reported immunogenicity comparison was at day 14, and the trial assessed antibody responses rather than clinical efficacy; the authors call for larger studies to assess efficacy.