Even as China struggles to contain the Covid outbreak, it is racing to develop its own messenger RNA vaccine, media reports said.
China’s pharmaceutical companies have used traditional inactivated virus technology in vaccines, and a progress towards a domestic mRNA vaccine has been slow in the country, Financial Times reported.
Chinese pharmaceutical companies had opted for the “old-fashioned [inactivated] vaccine” because the “existing technology was easily available and had been used in vaccines that had inoculated billions of people”, Jerome Kim, Director-general of the International Vaccine Institute in South Korea, was quoted as saying.
But researchers maintain that inactivated vaccine technology produces a weaker immune response. On the other hand, mRNA and viral-vector vaccines induce a targeted response to the virus’ spike protein as it enters human cells, compared with the inactivated vaccine, which attacks many viral proteins.
China’s pandemic strategy – strict lockdown measures on communities with local cases – has proved effective at preventing the large number of deaths suffered in some western countries. But the recent outbreak in Xi’an, with more than 1,758 cases, has underscored officials’ lack of confidence in domestic jabs, the FT report said.
“The lower efficacy of the Chinese vaccines indicates that most people lack the necessary neutralising antibodies to prevent infection or severe cases,” Jin Dong-yan, a virologist at the University of Hong Kong, was quoted as saying.
Research from the university showed that two jabs and a booster of Sinovac’s vaccine provided insufficient protection against the Omicron variant, while another study demonstrated that both Chinese vaccines’ efficacy declined quickly. China has so far administered 2.8bn doses of Sinopharm and Sinovac’s inactivated virus vaccines to 1.2bn people.
As China was slow to develop mRNA technology, its pharmaceutical companies lacked the scientific knowhow and specialised machinery to deliver the jab at scale, Dong-yan said.
He added that there were significant technical barriers to making lipid nanoparticles, the fatty shield that protects fragile mRNA molecules when entering human cells, which are difficult to create safely and in large quantities, the report said.
But even if China rolls out an mRNA vaccine as a booster, experts warned that it may not be a silver bullet that gives authorities the confidence to end its zero-Covid policy.
An immunology professor from Beijing, who did not want to be named, said that even if China rolled out its own mRNA vaccine, “it wouldn’t have a big impact on China’s pandemic control measures” since evidence from existing versions of the jab showed that breakthrough infections are still possible, the report said.