Researchers at the Indian Institute of Science (IISc) have designed a “heat-tolerant” Covid-19 vaccine candidate that can ease the requirement for a cold chain for a vaccination programme. The design was recently published in the Journal of Biological Chemistry.
It is a protein subunit vaccine that uses a part of the virus’ spike protein called the receptor-binding domain (RBD) — the part that allows the virus to connect with the host cell to enter it. It differs from other vaccine candidates being developed as it only uses a specific part of the RBD — a string of 200 amino acids, instead of the entire spike protein. The researchers found that it was effective in getting an immune response in the guinea pigs but remained stable at higher temperatures.
When tested on guinea pig models, the vaccine candidate triggered a strong immune response.
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The vaccine candidate remained stable for a month at 37°C, and freeze-dried versions could tolerate temperatures as high as 100°C. This will be a boon for mass vaccination campaigns, especially in lower-and middle-income countries, as expensive cooling mechanisms would not be needed to transport the vaccine to remote areas.
Compared to newer types such as mRNA vaccines, making a protein-based vaccine like this can also be scaled up easily in India where manufacturers have been making similar vaccines for decades.
The vaccine candidate was developed by a team led by Raghavan Varadarajan from Molecular Biophysics Unit at IISc and Mynvax, a startup incubated at IISc.
“Now we have to get funds to take this forward to clinical development,” said Varadarajan. This would include safety and toxicity studies in rats along with process development and GMP manufacture of a clinical trial batch before they are tested on humans. “Those studies can cost about Rs 10 crores. Unless the government funds us, we might not be able to take it forward.”