Covaxin phase 3 interim trial reveals 78% efficacy

The second interim Phase 3 analysis of the first make-in-India Coronavirus disease (Covid-19) vaccine, Covaxin, has shown 78% efficacy, its maker Bharat Biotech announced on Wednesday.

The company first released its preliminary Phase 3 analysis results in March, showing 81% efficacy based on 43 cases. In this round, a vaccine efficacy of 78% was recorded against mild, moderate, and severe symptoms of Covid-19 based on 127 cases.

The efficacy against asymptomatic Covid-19 infections was 70%, suggesting decreased transmission in Covaxin recipients, the analysis showed. The efficacy against severe Covid-19 disease was 100%, along with a reduction in the number of hospitalisations. “[The vaccine’s] efficacy against Sars-CoV-2 has been established. Covaxin has demonstrated an excellent safety record in human clinical trials and in emergency-use... The efficacy data against severe Covid-19 and asymptomatic infections is highly significant, as this helps reduce hospitalisations and disease transmission, respectively,” said Krishna Ella, chairman and managing editor, Bharat Biotech.

“The tireless efforts of our scientists at ICMR and BBIL have resulted in a truly effective international vaccine of the highest standards and efficacy. I am also happy to note that Covaxin works well against most variants of Sars-CoV-2. These findings together consolidate the position of our indigenous vaccine in the global vaccine landscape,” said Dr Balram Bhargava, director general, Indian Council of Medical Research (ICMR).

Bharat Biotech has co-developed Covaxin with ICMR.

ICMR said: “Covaxin neutralises against multiple variants of Sars-Cov-2, and effectively neutralises the double mutant strain as well.” Safety and efficacy results from the final analysis will be available in June, and the final report will be submitted to a peer-reviewed publication. Based on the achievement of the success criteria, placebo recipients have now become eligible to receive two doses of the vaccine.

A total of 25,800 participants, between the ages of 18 and 98 (including 10% over the age of 60), were enrolled in the Phase 3 study. The analysis was conducted 14 days after the second dose. Covaxin was developed with seed strains received from the National Institute of Virology, and the Phase 3 clinical trial was co-funded by ICMR, making it a public-private partnership effort towards public health.

“Covaxin’s evidence-based development has proved its suitability for global access, with excellent efficacy results against symptomatic, asymptomatic, and severe disease. The interest from countries worldwide has quietly validated our efforts,” said Suchitra Ella, joint managing director, Bharat Biotech.

“For a respiratory vaccine, 78% efficacy is good,” Dr GC Khilnani, former head, pulmonology department, AIIMS, Delhi, said.