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Bharat Biotech an Indian Pharmaceutical company recently shared the results of their COVID-19 vaccine candidate safety trials in animals. The experimental shot, called 'COVAXIN', was found to be safe in rhesus monkeys that were vaccinated and exposed to the SARS-CoV-2.
Bharat Biotech has got approval from Drugs Controller General of India (DCGI), Indian regulatory agency for phase 1, and phase 2 trial of the vaccine in June 2020. In collaboration with the Indian Council of Medical Research (ICMR) and National Institute of Virology (NIV), designed an inactivated vaccine to produce unique elements of the SARS-CoV-2 virus, which are used by the immune system to recognize a threat. Phase 1 human trials were conducted at 12 sites across the country. The principal investigator of trials Dr. Savita Verma at Post Graduate Institute (PGI) of Medical Sciences said that no adverse events were reported in subjects and the vaccine is safe and ready to proceed to phase 2 trials are likely to begin in the first week of September, as per the report.
The animal trials demonstrated 'COVAXIN' protected SARS-CoV-2, and amped up two kinds of antibodies needed for a strong immune response against the virus.
Bharat Biotech had tested its vaccine candidate, was found to generate robust immune responses. Thus, preventing infection and disease in the macaques upon high amounts of exposure to live SARS-CoV-2 virus.
The vaccine was tested in 20 rhesus macaques. The primates were administered a “two dose vaccination regimen of inactivated SARS-CoV-2 vaccine”. One group was administered with placebo, while three groups were immunized with three different vaccine candidates at 0 and 14 days. All the macaques were exposed to viral challenge 14 days after the 2nd dose, the vaccine-maker said.
“The results showed protective efficacy, increasing SARS-CoV-2 specific IgG and neutralizing antibodies,” the company said, adding that it reduced the replication of the virus in the nasal cavity, throat, and lung tissues of the monkeys. Here are ten things we learned about the COVAXIN animal trials
Safety and protection against SARS-CoV-2 tested in monkeys. The animal trial (part of Phase I) was a test of how safe (three different formulations of) the inactivated COVID-19 vaccine was in rhesus macaques. Also measured was the shot's ability to offer protection against exposure to the SARS-CoV-2 virus.
Robust immune response was produced. The experimental COVAXIN shots reportedly prompted "robust" immune responses in monkeys. It worked in preventing SARS-CoV-2 infection and COVID-19 in all the monkeys given the vaccine. The vaccinated monkeys didn't fall ill with COVID-19 even when exposed to high levels of live SARS-CoV-2 virus in an artificial challenge.
Live virus challenge in monkeys. The vaccine was tested in 20 rhesus macaques, which were divided into 4 groups of 5 each. One group was given a placebo, while the other three groups were immunized with 3 different vaccine candidates on day 0 and day 14. Fourteen days after the macaques were given the second shot, scientists challenged them with live SARS-CoV-2 virus.
Two-dose regimen. COVAXIN is intended as a 2-dose vaccination and was tested in monkeys at two different concentrations – 3 µg and 6 µg doses, along with an adjuvant that enhances immune response. This regimen produced a "significant immune response" and offered protection against the SARS-CoV-2 virus, experts said in the trial report.
Two kinds of protective antibodies. The results from animal trial show that COVAXIN protected monkeys against the SARS-CoV-2 virus. There was an increase in two kinds of antibodies needed for a strong immune response – antibodies that can neutralize SARS-CoV-2 virus, and an important class of antibodies used to fight infection (SARS-CoV-2-specific IgG). This indicates that the experimental vaccine could similarly bring down the amount of virus replicating in the respiratory tract and organs like the nasal cavity, throat, and lung tissues.
Protection kicks in 3 weeks after vaccination. The protective response of COVAXIN seems to be much better in the third week of immunization, as per the report. This was when the levels of SARS-CoV-2-specific IgG and neutralizing antibodies were considerably higher than other time points in the trial.
No pneumonia after virus challenge. There was no evidence of pneumonia in the vaccinated macaques. Pneumonia has proven to be a key indicator in severe COVID-19 cases. When the placebo group was challenged with the SARS-CoV-2 virus, the monkeys showed interstitial pneumonia and virus particles in the lung tissue, showing that the infection continued.
Adverse events. The trial report claims that no adverse effects were seen in the animals with the two-dose vaccination regimen, which is an encouraging finding for the ongoing human safety trials.
Phase I human trials still underway. The information collected from the Phase I study substantiate the immunogenicity of the vaccine candidates and BBV152 is being evaluated in Phase I clinical trials in India (NCT04471519). The Phase I study involves 375 volunteers at 12 sites across the country, including PGI and All India Institute of Medical Sciences (AIIMS), Delhi. It is expected to be completed by the end of this month.
The report is under peer-review. The study has been pre-published in Nature Research and is still awaiting peer-review.