China Developing Its Own mRNA Vaccine To Fight COVID-19 Infection: Know All About It

How do mRNA vaccines work? How different are they from regular vaccines? Read on to find out.

China, the country where the first trace of COVID-19 virus was detected, remains one of the few not to have imported one of the exceptionally effective mRNA COVID vaccines developed by Pfizer and Moderna. Instead, the country has so far depended only on the vaccines which are developed by two Chinese companies, Sinovac and Sinopharm. However, this may be set to change, as the country is now developing its own mRNA vaccine.

To start with, both the Sinovac and Sinopharm vaccines are made with a traditional design, in which the vaccine containing whole forms of the coronavirus that have been inactivated a tried-and-tested way of making vaccines that work. However, while these vaccines were initially quite good at stopping people from getting symptomatic COVID, this protection waned significantly over time. These vaccines also offer poor protection against infection with omicron. This has put pressure on China to develop more effective vaccines, as it is pursuing a strict containment policy with the virus.

mRNA Vaccines: How Do They Work?

The mRNA vaccines work in a different way.

1. First, they deliver a snippet of the coronavirus's genetic code into the body, housed inside a lipid droplet.
2. Then, once this gets inside cells, the code gets read and the cells produce copies of a key part of the coronavirus, its spike protein.
3. Now, the immune system sees these spike proteins and mounts a response to them, generating immunity against the full virus should it be encountered in the future.

Why mRNA vaccines? The mRNA vaccines are usually generated with high levels of protection against getting COVID. And while the protection offered by two doses wanes over time and offers little protection against infection with omicron, the mRNA vaccines appear to offer the best protection against an omicron infection when used as boosters. They also continue to offer very impressive protection against severe disease. Early results suggest the third dose of Sinovac, in comparison, is unable to stop infection with the new variant (though these results are still in preprint, meaning they're awaiting review by other scientists).

ARCoV Vaccine Development

Therefore, according to the experts, the mRNA vaccine technology will offer the best protection against COVID in the future hence China's development of such a vaccine. But it hasn't just jumped on the bandwagon. Development of ARCoV, China's candidate mRNA vaccine, commenced in March 2020.

What is it? The technology used is very similar to that in the Pfizer and Moderna vaccines, using modified messenger RNA from the virus, housed in a lipid droplet, to stimulate immunity.

How do ARCoV works? rather than getting the immune system to respond to the full spike protein of the virus-like the Pfizer and Moderna vaccines do, ARCoV gets the body to make copies of the receptor-binding domain (RBD), a key subpart of the virus's spike protein that it uses to attach to and enter cells. This part of the virus seems to be especially recognisable by the immune system, which suggests that targeting it could have a particularly good protective effect.

What are the advantages? Another potential advantage ARCoV has over the earlier mRNA vaccines is that it is stable at 2-8 C for at least a month, which would make transporting, storing, and delivering the vaccine much easier.

China's COVID Vaccine: How Well Does It Work?

The results of an initial study of the vaccine in humans were published in January 2022 in The Lancet. The vaccine was found to be safe, but there was a higher rate of fever after vaccination, especially at higher doses, than was seen in early studies of the other mRNA vaccines. However, these fevers were short-lived.

(With inputs from Agencies)