CDSCO Panel Rejects Phase II Data for Reliance's RelCoVax COVID-19 Booster Over Immunogenicity Gap
New Delhi: The Subject Expert Committee (SEC) on COVID-19 vaccines, operating under the Central Drugs Standard Control Organisation (CDSCO), has rejected the Phase II clinical trial findings submitted by Reliance Lifesciences for its protein subunit COVID-19 vaccine candidate, RelCoVax, following a detailed scientific review.
The evaluation was carried out during the 01st/25th SEC meeting held on May 6, 2025, at CDSCO Headquarters, New Delhi.
Reliance Lifesciences submitted its proposal under file numbers BIO/PostAppr/2025/37220 and BIO/CT/23/000008, presenting a Phase II trial titled:
“A prospective, multi-center, randomized, open-label, active control, Phase II clinical study to evaluate immunogenicity, safety and tolerability of single heterologous booster dose of RelCoVax® (Protein Subunit Vaccine of Reliance Life Sciences against SARS-CoV-2 Virus) with Corbevax® (Protein Subunit Vaccine of Biological E Ltd. against SARS-CoV-2 Virus).”
The objective of the trial was to assess whether RelCoVax® could elicit an immune response comparable to Corbevax® when administered as a heterologous booster.
However, after a detailed deliberation, the SEC found that the vaccine did not meet the primary immunogenicity endpoint. As a result, the SEC concluded that RelCoVax® failed to demonstrate non-inferiority when compared to the reference vaccine and thus did not recommend the trial results for further regulatory consideration. It observed that;
"Immunogenicity results of the test vaccine did not meet the primary objective of the study as compared with the reference vaccine. The lower bound of 95% CI of difference in proportion of seroconversion rate in test v/s reference group did not meet the non-inferiority criteria of -10% as defined in the protocol. Hence, the vaccine did not demonstrate non-inferiority with the comparator vaccine."
