Animal trials of Bharat Biotech International Limited's Covid-19 vaccine candidate, Covaxin, have been successful and the results showed the shot's "remarkable immunogenicity and protective efficacy" in the Phase I clinical trials in India, the drugmaker has said.
Covaxin, developed by the Indian Council of Medical Research (ICMR) and Bharat Biotech, is being tested at 12 institutes across India. The Hyderabad-based firm said the data from the study on primates substantiate the immunogenicity of the vaccine candidate.
"Bharat Biotech proudly announces the animal study results of COVAXIN - These results demonstrate the protective efficacy in a live viral challenge model," Bharat Biotech tweeted on Friday.
Bharat Biotech has said in a release that it developed and assessed the protective efficacy and immunogenicity of an inactivated Sar-CoV-2 vaccine (BBV152) or Covaxin in rhesus macaques. Twenty macaques were divided into four groups of five animals each, it said.
"One group was administered a placebo while three groups were immunised with three different vaccine candidates at 0 and 14 days. All the macaques were challenged with SARS-CoV-2 14 days after the second dose. The protective response was observed with increasing SARS-CoV-2 specific IgG and neutralising antibody titres from third week post-immunisation," the drug company said.
It added that viral clearance was observed from "bronchoalveolar lavage fluid, nasal swab, throat swab, and lung tissues at 7 days post-infection in the vaccinated groups."
"No evidence of pneumonia was observed by histopathological examination in vaccinated groups, unlike the placebo group which showed features of interstitial pneumonia and localisation of viral antigen in the alveolar epithelium and macrophages by immunohistochemistry," it added.
"To summarize, the vaccine candidate was found to generate robust immune responses. Thus, preventing infection and disease in the primates upon high amounts of exposure to live SARS-CoV-2 virus," it added.
Bharat Biotech had received approval from the Central Drugs Standard Control Organisation to conduct the Phase-II trials earlier this month. It had announced in June that it successfully developed Covaxin in collaboration with ICMR and the National Institute of Virology (NIV).
The SARS-CoV-2 strain was isolated in NIV, Pune and transferred to Bharat Biotech. The indigenous, inactivated vaccine candidate has been developed and manufactured in Bharat Biotech's high containment facility located in Genome Valley, Hyderabad.
Covaxin is one of the frontrunners in the race for a Covid-19 vaccine in India. It is an "inactivated" vaccine — it works by injecting doses of the virus that have been killed aiming to prompt the body to build antibodies against it without the virus posing a threat.
Each stage of a vaccine's clinical trial tests its safety and ability to develop an effective immune response. Phase 1 focuses on determining safety and dosage in a small group of healthy participants, while Phase 2 looks at the vaccine's effectiveness. Phase 3 looks into these aspects in a much larger population that would represent a wider demographic.