Hyderabad-based vaccine manufacturing company Bharat Biotech on Wednesday announced that its indigenously-made Covaxin is 81% effective in preventing Covid-19 infections.
The results came after the third round of clinical trials that were conducted in partnership with the Indian government's medical research body ICMR.
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India's drug regulator committee had earlier last month asked Bharat Biotech to submit Covaxin's efficacy data. However, emergency use authorisation to the vaccine candidate was granted by the country's drug regulator back in January.
The vaccine was then rolled out, along with Serum Institute of India's Covishield, when India kicked off its inoculation drive on 16 January. It has since also been administered to the central government leaders after the second phase of the drive started.
In spite of this, several states and healthcare workers had shown reservation about giving and taking Covaxin until its efficacy becomes publicly available.
The hesitancy resulted in the government getting only about half the 30 million frontline workers it wanted to be vaccinated in the first phase of the programme.
Experts say that with the results out now, doubts related to the vaccine are expected to settle.
Here's all you need to know about Covaxin now
What is Covaxin's interim analysis based on?
The phase 3 trial involved 25,800 people between 18 and 98 years of age.
The analysis is based on 43 Covid-19 cases, of which 36 were in the placebo group and seven among those that received the vaccine.
The company expects to get a clearer picture of its efficacy once 130 cases are accumulated among its participants. "The clinical trial will continue through to final analysis at 130 confirmed cases in order to gather further data and to evaluate the efficacy of Covaxin in additional secondary study endpoints," the company said.
How effective is the vaccine when compared to Covishield?
Covaxin showed to be 81% effective in an early analysis of phase 3 trial, Covishield has an efficacy of 70.4% on average in preventing Covid-19 when its two doses are taken 28 days apart.
The efficacy of Covishield varies based on the duration between the first and second shots. According to Covishield’s product insert, this efficacy changes to nearly 79% if the second dose is administered at 12 weeks or longer.
But are both the vaccines' platforms similar?
The experimental vaccine, scientifically known as BBV152, contains inactivated whole SARS-CoV-2 virion.
The shot has been developed on the World Health Organization’s (WHO’s) prequalified vero cell platform, with a well-established track record of safety.
Vero cells are derived from the kidney of the African green monkey and are commonly used for developing vaccines.
On the other hand, Covishield is based on the viral vector platform. A chimpanzee adenovirus called ChAdOx1 is the vector that has been modified to carry the coronavirus spike protein into human cells.
The adenovirus vector platform for vaccines gained traction during the battle to stop Ebola.
How do they fare when it comes to new variants?
Bharat Biotech announced that Covaxin is effective against some of the new and more dangerous variants of the coronavirus.
An analysis from the National Institute of Virology (NIV), ICMR indicated that the vaccine can neutralize the UK variant and some other strains, ICMR said in a separate statement.
When it comes to Covishield, the vaccine has also been found to be effective against the UK variant of coronavirus. However, it only has 10% efficacy against South African variant N501Y.
Covaxin is yet to be tested on this strain.
India has reported more than 210 cases of the UK variant, four cases of the South African variant and one case of the Brazil strain.
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