Decoding Covaxin's Final Phase 3 Trial Data With Dr Shahid Jameel


Reporter, Producer: Anoushka Rajesh

Video Editor: Mohd. Irshad Alam


Covaxin, India's first fully home-grown COVID-19 vaccines has an overall efficacy of 77.8 percent, announced the vaccine's developer, Bharat Biotech on 3 July.

The final phase 3 clinical trial results released by the company also says that the vaccine is 65.2 percent effective against the Delta variant.

The long awaited phase 3 data is currently in the preprint stage and is yet to be peer reviewed.

What does this data mean? How was the vaccine's efficacy against the delta variant determined? How does Covaxin compare to other vaccines in India? FIT speaks to virologist, Dr Shahid Jameel.

Below are excerpts from the interview.

What do you make of this final data that has been released? The efficacy is a bit lower than what was released in the preliminary data.

As far as as the vaccine is concerned, the results are very similar to what was expected and what is seen in other vaccines.

It is very normal that the efficacy may go down a little bit (as compared to the interim results) and this is largely because t happened when India was going through a very bad second wave.

That's not good for efficacy but it's good in a sense because the vaccine protection got tested during the second wave.

This final data is as of yet a company claim and still needs to be peer-reviewed. What does that mean, why is it important?

Peer review is a process where other scientists look at the paper and give their comments before it is published in a regular journal.

This process is important because other scientists in the field can give their assessment of if the work is being done properly and if it is being reported properly.

In the meantime, can we take this final data at face value?

I don't think the numbers are going to change, unless peer reviewers find some drastic errors in the calculations which is unlikely. What could change is some details of the paper.

So yes, I think we can take this data at face value.


The data also says that Covaxin is 65.2 percent affective against the delta variant. How is this determined?

As you know we went through a second wave which was largely driven by the Delta variant.

The procedure is that everyone who tested positive were recorded and they would have sequenced the virus. On the basis of they would have well the vaccine protects against the delta variant in those who took the vacine compared to the placebo group.

So in a way it was good that the vaccine got tested during the second wave when Delta was raging through the country.

Do you think this data could lead to a WHO approval soon?

You have to understand that WHO approval doesn't come automatically. The company has to apply.

My understanding is that WHO and Bharat Biotech are in some pre-approval discussion.

But certainly, putting out the data in the public domain is going to help.

How does Covaxin compare to Covishield and Sputnik V? Should we be making the comparison at all?

I don't think we should be making these comparisons because no vaccine is tested against each other.

In every trial, the conditions are slightly different and therefore, to compare the efficacy of one vaccine to another is not the right move.

The most important thing is that all vaccines irrespective of their efficacy re protecting against severe disease and hospitalisation.

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