A booster dose of China's first ever mRNA-based Covid vaccine may be potent against Omicron, according to a study.
However, two doses of the vaccine called ARCoV has seen a significant drop in its ability to neutralise the Omicron strand of the coronavirus compared to its effectiveness against a wild-type strain with no major mutations, the South China Morning Post reported.
ARCoV is being jointly developed by the Academy of Military Medical Sciences, Suzhou Abogen Biosciences, and Walvax Biotechnology, and is at the final stage of a multiregional phase 3 clinical trial.
The vaccine is being developed using the same revolutionary mRNA technology, as the Pfizer-BioNTech and Moderna products.
The study analysed serum samples from 11 vaccinated people, eight of whom "retained low but detectable neutralisation activity against Omicron", researchers said in a letter published in the journal Cell Research.
A third dose was given to a group of lab mice that had already received two doses of ARCoV, and it readily induced the production of neutralising antibodies against Omicron and a wild-type strain, the letter said.
The study highlighted the benefits of a homologous booster vaccination and supported further validation of the vaccine in clinical trials.
"Our data presented here clearly demonstrate that a third dose of ARCoV would probably lead to a sharp increase in neutralisation antibodies not only against the wild type SARS-CoV-2 but also the new Omicron variant," the letter said.
"Homologous booster vaccination with ARCoV represents a rational strategy in response to the Omicron emergency," it added.
China has, so far, relied on traditional "inactivated" vaccines, which have been proved less effective against the Omicron and Delta variants.
The ArCoV vaccine is the first mRNA vaccine candidate against the Omicron variant that has been validated in animals, the report said.
Chinese researchers are approaching clinical trials to test its safety and efficacy, according to the study.
Chinese regulators have also not approved any vaccine developed overseas.
In July, last year, Shanghai-based Fosun Pharmaceuticals came closest by earning a recommendation from the government's expert panel for the Pfizer/BioNTech vaccine, the report said.