NEW DELHI: A heat-stable Covid-19 vaccine being developed in India that doesn’t require cold chain storage has generated a strong antibody response against coronavirus variants including Delta and Omicron, according to a study in mice.
The vaccine candidate, developed by the Indian Institute of Science (IISc) in Bengaluru and biotech startup Mynvax, uses a part of the viral spike protein called the receptor-binding domain (RBD), which allows the virus to attach to the host cell to induce them to infect.
The team, which included researchers from Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), found that most vaccines need to be refrigerated to remain effective. The heat-tolerant Covid-19 vaccine candidate can be stored at 37 degrees Celsius for four weeks and at 100 degrees Celsius for up to 90 minutes.
In comparison, the Oxford-AstraZeneca vaccine, known as Covishield in India, needs to be stored between 2 and 8 degrees Celsius, and Pfizer’s preventative requires special cold storage at minus 70 degrees Celsius.
The latest study, recently published in the journal Viruses, looked at sera (blood samples) from vaccinated mice for their effectiveness against key coronavirus variants, including Delta and Omicron.
The study found that mice immunized with different formulations of the vaccine elicited high titers (units used to measure amount or concentration) of antibodies targeting SARS-CoV-2 variants VIC31 (reference strain), delta and omicron Neutralizing variants of the coronavirus.
Compared to VIC31, there was an average 14.4-fold reduction in neutralization against the Omicron variant for one formulation of Mynvax vaccine and a 16.5-fold reduction for another formulation.
The corresponding values for the reduction in neutralization compared to the Delta variant were 2.5 and 3, according to the researchers.
“The average 14.4 and 16.5 fold reduction in neutralization against Omicron BA.1.1 for the monomeric and trimeric formulations, respectively, compare favorably to the corresponding reductions observed with leading Covid-19 vaccines” , the authors of the study noted.
“Our results suggest that monomeric formulations are amenable to upcoming Phase I human clinical trials and that there is potential to increase efficacy through vaccine customization to improve responses to emerging variants,” they wrote in the journal .
Monomeric and trimeric formulations refer to different forms and combinations that can be used to develop the vaccine.
CSIRO’s evaluation of the various Mynvax formulations will assist in the selection of the most appropriate candidate and dosage for planned human clinical trials in India.
The vaccine’s heat tolerance and its ability to withstand transient thermal shocks hold particular promise for addressing vaccine inequality affecting most low- and middle-income countries, the researchers added.
Over 10 billion doses of Covid-19 vaccines have been administered worldwide and 51 countries have reached more than 70 percent of their populations. In low-income countries, however, this is only 11 percent.
