Tests on mixing vaccines and the effectiveness of a single dose of Covishield will begin soon in the government's new strategy at a time the shortage of Covid shots has slowed down vaccinations.
Sources say a study on mixing two different vaccines will start in a month and will likely be completed in two to two and a half months.
The centre will assess vaccine data recorded on a new App, which will make it easier to report adverse events after vaccination. The platform, which is to be linked to CoWin, will allow people to flag their worries after a shot, after which a district officer will follow up on the cases.
Recently, after 20 people were accidentally injected with two different vaccines, the centre had ruled out any cause for concern.
VK Paul, NITI Aayog member and the head of India's Covid task force, had said in-depth research was needed to check whether mixing vaccines is effective.
This is a key aspect of the new vaccination strategy devised in line with the target of one crore inoculations daily by mid-July.
The government will also review the impact of its decision to extend the gap between Covishield doses, which will also help decide on a possible single-dose plan for the vaccine produced by Serum Institute of India.
Single dose vaccination will help the government cover a much wider base of the population, sources say.
They also point out that Oxford-Astrazeneca's vaccine - which is Covishield in India - started out as a single dose option before effectiveness studies recommended two shots.
There is a view that a single shot is enough protection from the virus, says NK Arora, chairman of the COVID-19 working group under the National Technical Advisory Group on Immunization (NTAGI).
Vaccines like Johnson & Johnson and Sputnik Light, which are based on a similar principle as Astrazeneca, are single dose, sources point out, so Covishield should work as one too.
"We are evaluating how effective is a single shot of Covishield. All these vaccines, Johnson and Johnson, Sputnik Light, Covishield are based on the same principle," Dr Arora said.
Serum's Covishield and Bharat Biotech's Covaxin are the two main shots used in the nationwide vaccination drive that started in January.
Russia's Sputnik is the third vaccine to be cleared for use.
The government is trying to procure 30-32 crore vaccine doses a month to tide over the current shortage.
These include 25 crore doses of Covishield and Covaxin.
The government is also banking on more vaccines in the coming months, including Biological E's Johnson & Johnson, Serum's Novovax, Genova mRNA and Zydus Cadila's DNA vaccine besides Sputnik.