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‘Encouraging Findings’: Covaxin has 81% Efficacy in Phase 3

Covaxin has an interim clinical efficacy of 81 per cent against COVID-19 said the company on Wednesday.

Updated
Covaxin Phase 3 results: 81 percent efficacy, says interim analysis
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On Wednesday, 3 March, Hyderabad-based vaccine manufacturer Bharat Biotech announced the phase 3 clinical results of their indigenously-made COVID-19 vaccine candidate Covaxin. As per the trial results, Covaxin has an interim clinical efficacy of 81 per cent against COVID-19 in those without prior infection after the second dose.

The data has come from 25,800 trial participants who received a vaccine or placebo in a 1:1 ratio that showed that the vaccine candidate was well-tolerated, said a report by the company. The first interim analysis is based on 43 cases.

These trials were conducted in partnership with the Indian Council of Medical Research (ICMR) and National Institute of Virology (NIV). More data is expected as the clinical trial will continue through to the final analysis at 130 confirmed cases to further evaluate the efficacy of the vaccine.

FIT speaks to ex-Head Scientist of Epidemiology and Communicable Diseases at ICMR, Dr Gangakhedkar and Dr Swapneil Parikh, Internal medicine specialist in Mumbai and author of ‘The Coronavirus: What You Need to Know About the Global Pandemic’ to find out more.

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“The efficacy sounds to be good as a point estimate. The numbers are small but its good news for the vaccine. We need to wait for subsequence results as they have indicated. The point estimate currently is very much in favour of the vaccine. It puts covaxin in the league of other vaccines around the world.”
Dr Gangakhedkar

When asked if the prelim data was based on a very small number, he added, "Pfizer and Moderna also released prelim data based on small numbers. In a pandemic like situation, it is important to study initial data set. You can then proceed to add more data to the findings."

“These are encouraging findings,” says Dr Gangakhedkar.

Dr Parikh said, “It’s wonderful news that interim analysis from the COVAXIN phase 3 trial suggests the vaccine is efficacious. We need to wait for the pre-print to see the confidence in this data but this is great news for our country!”

Bharat Biotech's chairperson, Dr Krishna Ella, said,

“Today is an important milestone in vaccine discovery, for science and our fight against coronavirus. With today’s results from our Phase 3 clinical trials, we have now reported data on our COVID-19 vaccine from Phase 1, 2, and 3 trials involving around 27,000 participants. Covaxin demonstrates high clinical efficacy trend against COVID-19 but also significant immunogenicity against the rapidly emerging variants.”
Dr Krishna Ella, Chairman & Managing Director, Bharat Biotech.

Meanwhile, ICMR’s Director-General, Dr Balram Bhargava added, “The bench-to-bedside journey of completely indigenous COVID-19 vaccine in less than 8 months’ time showcases the immense strength of Atmanirbhar Bharat [self-reliant India] to fight the odds and stand tall in the global public health community. It is also a testament to India’s emergence as a global vaccine superpower.”

Covaxin has been developed on the WHO prequalified vero cell platform.

In a press release by ICMR, Dr Samiran Panda, Head, Epidemiology and Communicable Disease, ICMR and Director, National AIDS Research Institute added,

“The development and deployment of COVAXIN ensures that India has a powerful weapon in its arsenal in a continually evolving pandemic situation and will go a long way in helping us win the war against COVID-19. The need of the hour is to ensure that people in India continue to receive the vaccine and break the chain of virus transmission.”
Dr Samiran Panda, ICMR

Study Details

The Phase 3 study enrolled 25,800 participants between 18-98 years of age, including 2,433 over the age of 60 and 4,500 with comorbidities.

The primary endpoint of Phase 3 clinical trial is based on the first occurrence of PCR-confirmed symptomatic (mild, moderate, or severe) of COVID-19 with the onset at least 14 days after the second study vaccination in serologically negative (to SARS-CoV-2) adult participants at baseline.

The first interim analysis is based on 43 cases, of which 36 cases of COVID-19 were observed in the placebo group versus 7 cases observed in the Covaxin group, resulting in a point estimate of vaccine efficacy of 80.6%.

The phase III study of the Covaxin, which initially spanned at 25 clinical sites across the country, inducted several more sites in the last week of December since many sites were unable to find the volunteers for the study.

Dr Dhananjay Lad, co-investigator of the trial at Redkar Hospital, Goa, told IANS that the trial was extended to around 30 clinical sites

"A few sites were also removed in the process because of several reasons. One of the reasons was the inability to enrol a bare minimum number of participants," he said.

The trial was started with three sites each in Uttar Pradesh (Aligarh Muslim University), West Bengal (ICMR-National Institute of Cholera and Enteric Diseases), and Tamil Nadu (Directorate of Public Health and Preventive Medicine) on November 10.

Adverse Events:

The company said that the interim analysis included a preliminary review of the safety database, which showed that severe, serious, and medically attended adverse events occurred at low levels and were balanced between vaccine and placebo groups.

Early Trials

Previously, pre-clinical studies in small animals and hamsters showed promising results in terms of safety and immunogenicity and further studies conducted in the rhesus macaques also established the safety and protective efficacy of COVAXIN.

“Phase 1 and Phase 2 clinical trials conducted in 755 participants demonstrated a high safety profile of the candidate vaccine with seroconversion rates of 98.3% and 81.1% on day 56 and 104 respectively,” said the ICMR pres release.

Covaxin & the UK Strain

Analysis from the National Institute of Virology indicates that vaccine-induced antibodies can neutralize the UK variant strains and other heterologous strains, which has been published in bioRxiv. This is a pre-print and has not been peer-reviewed.

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