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New Delhi: A heat-stable COVID-19 vaccine that is being developed in India and does not require cold chain storage has generated strong antibody responses against coronavirus variants, including Delta and Omicron, according to a study on mice. The vaccine candidate by the Indian Institute of Science (IISc) in Bengaluru and biotech start-up company Mynvax uses a part of the viral spike protein called the receptor-binding domain (RBD), which allows the virus to bind to the host . cell to infect it.

The team, including researchers from Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), noted that most vaccines require refrigeration to remain effective. The heat-tolerant COVID-19 vaccine candidate can be stored at 37 °C for up to four weeks and at 100 °C for up to 90 minutes. In comparison, the Oxford-AstraZeneca vaccine, known in India as Covishield, needs to be stored between 2-8°C and the Pfizer preventative requires special cold storage at minus 70°C.

The latest study, recently published in the journal Viruses, assessed vaccinated mice sera (blood samples) for efficacy against major coronavirus variants, including Delta and Omicron. The study found that immunized mice with different formulations of the vaccine elicited high titres (unit for measuring quantity or concentration) of antibodies that could bind to the SARS-CoV-2 variant VIC31 (reference strain), the delta and omicron variants of the coronavirus. neutralize. Compared to VIC31, there was an average 14.4-fold reduction in neutralization against the Omicron variant for one formulation of the Mynvax vaccine and a 16.5-fold reduction for the other formulation.

According to the researchers the respective values ​​for the reduction in neutrality against the delta variant were 2.5 and 3. The study authors noted that the average 14.4- or 16.5-fold reduction in neutralization against Omicron ba.1.1 for the monomeric and trimeric formulations, respectively, is consistent with similar reductions seen with the major COVID-19 vaccines. Our findings suggest that the monomeric formulations are suitable for upcoming phase I human clinical trials and have the potential to increase efficacy with vaccine matching to improve responses against emerging variants, they wrote in the journal.

Monomeric and trimeric formulations refer to the different shapes and combinations that can be used to develop a vaccine. CSIRO’s evaluation of the various Mynvax formulations will aid in the selection of the most suitable candidate and dosage regimen for planned human clinical trials in India. The vaccine’s heat tolerance and ability to withstand transient thermal shock are particularly promising to address the vaccine disparity that plagues most low- and lower-middle-income countries, the researchers said. Globally more than 10 billion doses of COVID-19 vaccines have been given and 51 countries have reached more than 70 percent of their population. However, it is only 11 per cent in low-income countries.

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