Covaxin’s Phase 1 study data shows a robust response: Bharat Biotech

Indigenous vaccine candidate Covaxin, developed by Hyderabad-based Bharat Biotech International (BBIL), appeared to be nearing approval as the results of the Phase 1 clinical trial showed a “robust” immune response with no serious adverse events, a research paper.

Bharat Biotech recently requested accelerated regulatory approval based on Phase 1 and 2 studies. The company is currently conducting a phase 3 study with 22,000 subjects. The Serum Institute of India, which works with Astra Zeneca and Oxford University on Covid vaccines, has also applied for an emergency permit. Pfizer-BioNTech has also applied for this.

Only one serious adverse event that was not causally related to the investigational drug was reported around August, Bharat Biotech said in the publication.

For the first time, the company outlined its efforts, saying that the phase 1 study was conducted with 375 volunteers in 11 hospitals. In an interim report, BBIL said that all three vaccine formulations (different dosages) produced “robust immune responses comparable to a group of convalescent serum”. In other words, the responses induced by the vaccine were comparable to those seen in the convalescent serum of patients who had recovered from Covid-19.

One serious adverse event was reported in the group that received the 6 micrograms dose. “The participant was screened on July 25 and vaccinated on July 30. Five days later, the participant reported symptoms of Covid-19 and found positive for SARS-CoV-2 (by a nucleic acid test). Symptoms were mild in of nature, but the patient was hospitalized on Aug. 15, “the company said in the report.

It added that the participant was discharged on August 22nd after a negative nucleic acid result. “The event was not causally related to the vaccine,” said BBIL.

Most of the adverse events following the first vaccination were mostly mild or moderate and were “quickly resolved” without prescribed medication. Covaxin is tested in two doses about 28 days apart. After the second shot was administered, injection site pain was the most common localized adverse event.

No significant differences between the volunteers were found for the two dose arms, one 3-microgram and another 6-microgram. All vaccinated persons showed neutralizing reactions to Sars-CoV-2 strains.


However, this is an interim report and BBIL said it did not report any data on persistence of vaccine-induced antibody responses or safety results. The results reported here do not allow any effectiveness assessments. The evaluation of the safety results requires more extensive phase 3 clinical studies.

Krishna Ella, CMD of Bharat Biotech, said at an event that the company had already recruited 8,000 people for the Phase 3 clinical trials.

BBIL ​​began Phase 3 trials on November 17th.

The company has applied for a marketing authorization based on Phase 1 and 2 data, he added. Ella believed that since data from monkeys showed the vaccine’s effectiveness, and Phase 1 and 2 data in humans showed it is safe, a marketing authorization application could be made. Commenting on the vaccine development process, Ella said, “Everything was done to international standards.”

“We are not inhuman people, we are sensitive to our volunteers. We cannot reveal their names for reasons of confidentiality. Transparency means whether we report events to the regulator, the data and security monitoring body and the ethics committee,” Ella had said .

“The vaccine is safe, based on tried and tested technology. It can be given to a six-month-old or a 60-year-old,” he said.

BBIL ​​noted in the research report that vaccines inactivated with the whole virus have been used for decades and have a well-established safety profile. “Bharat Biotech manufactures several Vero cell-derived, inactivated, all-virion-approved vaccines (5-7) and two investigational candidates (Zika and Chikungunya). We have collected safety data from 4,700 participants in Phase 1-3 clinical trials and conducted pharmaceutical collaborations. Vigilance reports on all approved vaccines (approximately 100 million doses administered), “he added.