Bharat Biotech's Covaxin Has 81% Efficacy. Here's How it Compares to Serum Institute's Covishield

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Bharat Biotech in a statement said that Covaxin vaccine was 81 per cent effective in preventing Covid-19 after a third round of clinical trials. Covaxin demonstrated 81 per cent interim efficacy in preventing Covid-19 in those without prior infection after the second dose, said the statement.

Here is what this data means and how it stacks up against India’s second vaccine option:

What is the meaning of efficacy?

Efficacy is calculated in percentage form and denotes the measure of how much protection the vaccine provides against the virus, compared with the situation in which they were not vaccinated. Efficacy is calculated on parameters such as the ability of the shot to prevent mild to severe symptoms from showing even if you have been infected, to preventing you from getting infected with the disease altogether.

In the case of Covid-19 vaccines, pharma companies have primarily focused on bringing down the number of symptomatic cases.

How does Covaxin’s efficacy stack up against Covishield?

In the case of Covaxin, data from 25,800 participants received a vaccine or placebo in a 1:1 ratio showed that the vaccine candidate was well tolerated.

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 percent.

Covishield, on the other hand, has an efficacy of 70.4 per cent on an average in preventing Covid-19, as per the interim analysis of its late-stage clinical trials conducted in the UK and Brazil.

In Brazil, two full doses of the vaccine were given one month apart, involving 8,895 participants, and the vaccine appeared to be 62 percent effective.

What is Covaxin’s platform?

Covaxin is based on an inactivated whole SARS-CoV-2 virion, an old platform that is also used to make polio vaccines. A virus’s disease-producing capacity is inactivated under this method.

How efficient is Covaxin against South Africa and UK variant of the virus?

Covaxin is yet to be tested on this strain. However, in theory, the inactivated vaccines, such as Covaxin, provide broader protection against mutating variants.

What are its supply requirements?

Covaxin is stable at 2 to 8 degree Celsius (refrigerator temperature) and are shipped in a ready-to-use liquid formulation that permits distribution using existing vaccine supply chain.

What is the approval parameter of Covaxin?

On January 3, the Drugs Controller General of India (DCGI) had approved Covaxin for ‘emergency use’ under ‘clinical trial mode’.