Bharat Biotech's Covaxin succeeds in challenge trials on Rhesus monkeys

The results showed protective efficacacy, increasing Sars-CoV-2 specific IgG and neutralising antibodies reducing the replication of the virus in the nasal cavity, throat and lung tissues of monkey

Hyderabad-based Bharat Biotech has released the data from the animal trials of its vaccine candidate, which showed that Covaxin was able to generate 'robust immune responses'. 

The firm said that the vaccine prevented infection and disease in the primates upon high amounts of exposure to live virus Sars-CoV-2. This is called a challenge trial where a participant is exposed deliberately to the pathogen after being given the vaccine shot. 

The company tweeted "Bharat Biotech proudly announces the animal study results of Covaxin–-these results demonstrate the protective efficacy in a live viral challenge model." 

The indigenously-developed vaccine by Bharat Biotech and the Indian Council of Medical Research (ICMR), the country's apex health research organisation. It is now undergoing trials at 12 sites across India. 

 

Bharat Biotech noted on its website that the vaccine was given (as a two dose vaccination regimen) to 20 rhesus macaques who were divided into four groups. One group was given placebo, while three groups were immunised with three different vaccine candidates at zero and 14-days. "All the macaques were exposed to viral challenge 14 days after the second dose," the company said. 

The results showed protective efficacy, increasing Sars-CoV-2 specific IgG and neutralising antibodies reducing the replication of the virus in the nasal cavity, throat and lung tissues of the monkeys. Bharat Biotech also noted that no evidence of pneumonia was observed in the vaccinated groups unlike the placebo group.  "Adverse events were not seen in animals immunized with a two-dose vaccination regimen," it added. 

Summary of the outcomes: 

. A 2-dose vaccination regimen of inactivated SARS-CoV-2 vaccine candidates was administered in 20 rhesus macaques (divided into four groups equally)

. One group was given placebo, while three groups were immunised with 3 different vaccine candidates at zero and 14 days

. All the macaques were exposed to viral challenge 14 days after the second dose

. The results showed protective efficacy, increasing SARS-CoV-2 specific IgG and neutralising antibodies

. Reduced replication of the virus in the nasal cavity, throat, and lung tissues of monkey

. No evidence of pneumonia was observed in vaccinated groups, unlike the placebo group

. Adverse events were not seen in animals immunised with a two-dose vaccination regimen