Most COVID-19 vaccines under development need cold temperature handling. They must be kept under sub-zero temperatures from transporting to distributing in a handling process called 'cold chain'. There is a pictorial from a BBC site at the bottom of the post.
Here is a quote from the link below:
"Most vaccines need to be stored within 1-degree Fahrenheit of their ideal temperature. Traditional vaccines are usually stored between 35 degrees Fahrenheit and 46 degrees Fahrenheit, but some of the leading COVID-19 vaccines need to be stored at much colder temperatures. Moderna’s vaccine requires a storage temperature of minus 4 degrees Fahrenheit, whereas Pfizer’s vaccine candidate requires a storage temperature of minus 94 degrees Fahrenheit. These are not easy temperatures to maintain accurately."
https://www.discovermagazine.com/health/keeping-coronavirus-vaccines-at-subzero-temperatures-during-distribution
While this is not a such serious issue for most urban locations it could be a problem in rural, or isolated communities. It is all the more restrictive for semi-developed, or under developed regions of the world. For example, certain regions in India can have temperature that can exceed +50 deg C. The same can be said of many African and Latin American Countries.
There is therefore a need for vaccines that can retain their effect at higher temperatures that need no cold chain.
An Indian team at the Indian Institute of Science have tested a vaccine on animals that can be stored at 37 deg C for more than a month.
https://en.wikipedia.org/wiki/Raghavan_Varadarajan
Their paper has been peer reviewed and according to the link below,
" ...paper has been accepted for publication in Journal of Biological Chemistry, a peer-reviewed scientific journal, published by the American Society for Biochemistry and Molecular Biology.
You can find more details here:
https://www.bbc.com/news/world-asia-india-54792287
Pictorial of cold-chain:
