Bharat Biotech's coronavirus vaccine Covaxin has been found to be well-tolerated and produced an immune response, says the Phase-1 interim data published by the company in the peer-reviewed British medical journal Lancet.
The findings come at a time amid reports that some healthcare workers, including doctors, were not turning up to take the indigenously developed jab, which was given the emergency approval under the "trial mode", over safety concerns. India rolled out its vaccination drive on January 16 and will innoculate frontline workers first.
In Phase-1, potential vaccines are tested on healthy human volunteers to check for the safety or potential side-effects of the vaccine and the immunogenicity, or the immune response that enables the body to fight an infection.
Covaxin has been developed by the Hyderabad-based biotechnology firm in collaboration with the Indian Council of Medical Research and the National Institute of Virology. The vaccine is now undergoing phase-3 trials. Phase 2 trials are being analysed.
Also read: Healthcare workers feel used as ‘guinea pigs’, hesitate to take Covaxin: Report
Bharat Biotech conducted the Phase-1 study between July 13 and 30, 2020. The company said it screened 897 individuals but ended up enrolling 375. The participants were between 18 and 55 years of age.
The duration of the study is 12 months, which means that all the participants will be followed-up during this period.
The most common adverse event was pain at the injection site followed by headache, fatigue, and fever, the study said.
The overall incidence of solicited local and systemic adverse events in this study was 14–21 percent in all vaccine-treated groups. The company said the incidence of adverse events were noticeably lower than the rates for other SARS-CoV-2 vaccine platform candidates.
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Among the enrolled participants, 100 each were randomly assigned to the three vaccine groups and 75 to the control group (Algel only).
After both doses, solicited local and systemic adverse reactions were reported by 17 percent participants in the 3 µg with Algel-IMDG group, 21 percent in the 6 µg with Algel-IMDG group, 14 in the 6 µg with Algel group, and ten in the Algel-only group. Five percent participants complained of pain at the injection site. Headache and fatigue were reported by 3 percent, while fever and nausea in 2 percent.
Algel and IMDG are adjuvants that help to boost the vaccine efficacy.
Of the adverse events, 69 percent were mild and 31 percent moderate. These were more frequent after the first dose.
One serious adverse event of viral pneumonitis was reported in the 6 µg with Algel group, unrelated to the vaccine, the study said.
Immune response
According to the study, Covaxin has induced binding and neutralising antibody responses. On Day 28 or 14 days after the second dose, all subjects who received the vaccine intramuscularly had significantly elevated spike binding IgG antibodies and neutralising antibody titers.
The inclusion of the Algel-IMDG adjuvant helped the vaccine to induce a Th1-biased response or T-Cell response, that provides adaptive immunity.
The vaccine has been approved for restricted emergency use under clinical trial mode. The government has procured 55 million doses of the vaccine, and has begun vaccination rollout.
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