BEIJING -- A group of Chinese virologists have developed a technique that helps store mRNA-based COVID-19 vaccines at normal temperature for more than half a year.

Most current mRNA vaccines require to be stored at minus 20 to 70 degrees Celsius due to their poor stability, thus restricting their availability.

The study published in the journal Cell Discovery this week showed that a kind of freeze-dry lipid nanoparticle vaccine prepared via an optimized lyophilization technique with precise temperature control and lower residual water content can remain physiochemically stable at 25 degrees Celsius over six months while eliciting potent humoral and cellular immunity in mice, rabbits, or rhesus macaques.

In the human trial, administration of lyophilized Omicron mRNA vaccine as a booster shot also engendered strong immunity, and the titers of neutralizing antibodies against multiple Omicron variants are seen to increase by at least 253-fold after a booster shot following two doses of the commercial inactivated vaccine, according to the study.

The technique overcomes the instability of mRNA vaccines without affecting their bioactivity and significantly improves their accessibility, particularly in remote regions, said the researchers.