81% Efficacy For Bharat Biotech’s Covaxin

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What has happened?

Hyderabad-based vaccine manufacturing company Bharat Biotech on Wednesday announced phase 3 clinical results of its indigenously-made Covid-19 vaccine candidate, Covaxin.
In the trial results, the company says that Covaxin demonstrates an interim clinical efficacy of 81% against novel coronavirus.

The efficacy of a vaccine is a way to show how much the jab protects people against a virus or bacteria compared with if they would not have been vaccinated.
More specifically, it looks at the ability of the vaccine to protect the population inoculated using various parameters.
These range from the ability of the shot to prevent mild to severe symptoms from showing even if you’ve been infected to preventing you from getting infected with the disease altogether.
In the case of Covid-19, several companies have primarily been focused on bringing down the number of symptomatic cases —
Even if you’re infected by the SARS-CoV-2, you may not present with the symptoms and fall as sick as you would have without a vaccine.
Bharat Biotech, through its Phase 3 clinical trials involving 25,800 volunteers across the country, has also been focused on understanding Covaxin’s efficacy to prevent symptomatic, including severe symptomatic Covid-19 cases.

According to the interim results, the vaccine has an efficacy of 80.6%.
This means the vaccine was able to bring down the number of symptomatic Covid-19 cases by nearly 81% in those vaccinated in the trial as compared to the group that received a placebo.
The results were collected by studying 43 participants in the trial who had tested positive for Covid-19 two weeks after receiving their second dose and had presented with either mild, moderate or severe symptoms.
The trials were unblinded at this point to check how many of these participants had received Covaxin and how many got a placebo.
It was found that 36 out of these 43 participants had received a placebo, while seven had received Covaxin.

Covaxin is one of the two vaccines being used in India’s mass vaccination programme against Covid-19.
A higher efficacy would mean a higher chance at protecting the vulnerable population against the disease.
The findings are expected to add value to the vaccine and ease hesitancy related to it.
The vaccine had earlier come under fire for having received emergency approval without Bharat Biotech recruiting and vaccinating enough participants in its phase 3 trial to even provide an idea of its efficacy.
This meant, until now, no one knew how much protection this vaccine would actually be able to provide to those receiving it.

Covishield, the other vaccine being used in the government’s campaign, has an efficacy of around 53% when the second dose is given less than six weeks after the first dose, according to its product insert.
However, the efficacy of this vaccine, which is based on the AstraZeneca-University of Oxford jab AZD1222, varies based on the duration between the first and second shots.
Serum Institute of India, which manufactures Covishield, will also be making Covovax — a version of the Covid-19 vaccine developed by Maryland, US-based Novavax Inc.
In January, this vaccine demonstrated an efficacy of around 3% in the UK, and around 60% in South Africa.
Pfizer and BioNTech’s BNT162b2, which is currently not available in India, has demonstrated an efficacy of around 95%

There is disagreement over this point. But most experts feel it may not be fair to compare vaccines using different platforms and different clinical trial designs.
In the case of Covaxin, the data released is based on only 43 cases of Covid-19;
Bharat Biotech expects to get a clearer picture of its efficacy once 130 cases are accumulated among its participants.

There is still a lot left to know about Covaxin’s safety and aspects related to its efficacy, according to experts.
These results have so far not been published in a scientific journal or have been peer-reviewed.

Q) Which of the following statements regarding Zika virus is correct?