Covaxin, the vaccine candidate being developed by Bharat Biotech and ICMR-National Institute of Virology, is "safe" and induced "robust" immune response among Phase 1 trial participants. Bharat Biotech has sought emergency approval for Covaxin from the drug regulator. The application is under consideration as the subject expert committee has asked for additional data, health ministry has said.
According to the pre-print of the trial results published on December 15, the firm conducted a double-blind randomised controlled Phase 1 clinical trial to evaluate the safety and immunogenicity of BBV152, its whole-virion inactivated vaccine. The trial was done on 375 participants. The participants were randomised to receive one-two doses of the intramuscular vaccine with different adjuvants, and adjuvant-only, two weeks apart.
The outcomes being measured were reactogenicity and safety (primary); and the secondary outcome being measured was immune response. "Reactogenicity was absent in the majority of participants, with mild events. The majority of adverse events were mild and were resolved. One serious adverse event was reported, which was found to be unrelated to vaccination," authors report in the pre-print article. The article has not been peer-reviewed.
Authors of the interim analysis of the trial results include Dr Raches Ella, head of business development, Dr Balram Bhargava, director general, ICMR, Dr Randeep Guleria, director, AIIMS, Dr Pragya Yadav, National Institute of Virology, among others. In the article, they state that after the first vaccination, "local and systemic adverse events were predominantly mild or moderate in severity and resolved rapidly without any medication". A similar trend was observed after the second vaccination. Pain at the injection site was the most common local adverse event. One serious adverse event was reported where a participant was vaccinated on July 30, and after reporting symptoms, tested positive for SARS-COV2. "The symptoms were mild in nature, but the patient was admitted to the hospital on August 15. The participant was discharged on August 22..." the article reads. "The event was not causally associated with the vaccine," the authors conclude.
The authors also state the limitations of the study— as this is an interim report, no data on the persistence of vaccine-induced antibody responses or safety outcomes is being reported. Results reported in this study do not permit efficacy assessments, and evaluating safety outcomes requires more extensive Phase 3 trials, they state. This trial only evaluates accelerated schedule (vaccination occurred 2 weeks apart) and did not include a routine schedule (vaccination occurring 4 weeks apart). The latter schedule is being evaluated in Phase 2, the article reads.
Covaxin had been in the news recently after Haryana Health Minister Anil Vij, who had gone public with his participation in the Phase 3 trial, reported testing positive for COVID-19. In response to his diagnosis, the health ministry had said the minister had received only one dose of the vaccine. Concerns were raised by experts about the fact that since the trial was double blinded and randomised (participants and investigators don't know whether they are receiving or administering the vaccine) how the Union health ministry knew whether the minister was in the vaccine or control arm.