NEW DELHI - "Just to be clear, this is what our (Covid-19) vaccine looks like," Dr Sean Tucker, the chief scientific officer at Vaxart, an American biotechnology firm, said last week while on a Zoom call with The Straits Times.

In his hand was not a vial with a solution that has to be injected into the muscle, the way currently available Covid-19 vaccines are given.

Instead, he showed a single tablet in a blister pack - a tantalising prospect that people could soon pop a Covid-19 vaccine the way they would any ordinary pill.

It is this unprecedented challenge in vaccine storage and delivery that San Francisco-based Vaxart hopes to resolve with its tablet vaccine against Covid-19 that could be used across the world without the limitations of needle-based ones.

That is a huge advantage." Vaxart's tablet vaccine candidate is currently undergoing Phase II trials.

This is where warm vaccines such as IISc-Mynvax's, which is expected to be sold more cheaply than vaccines currently being used in India, could prove especially helpful in the campaign against Covid-19.

This is why, it said, heat-tolerant vaccines were never prioritised by vaccine developers, industries and funding entities despite their demand from low- and middle-income countries.

In May, its Covid-19 vaccine candidate reported encouraging Phase I results, showing higher CD8+ T-cell responses than the Pfizer and Moderna vaccines.

The firm expects to produce millions - potentially even billions of doses of its vaccine - every year at a price that Dr Tucker described as "cost-effective".

"Our technology can handle and attack the virus at multiple fronts that are different from the injected vaccines," Dr Tucker said.

Even today, there are not many warm vaccines in the pipeline.

BBC reported this week that Iconovo, a Swedish firm that produces inhaler devices and dry powder formulations for pharmaceutical companies, is collaborating with an immunology research start-up in Stockholm, ISR, which has developed a dry-powder vaccine against Covid-19.

The company is currently testing its vaccines on the Beta and Alpha variants of Sars-CoV-2.