A top Chinese health official has voiced caution about new vaccine technology used in coronavirus shots authorised in the United States and Britain.
George Gao Fu, director of the Chinese Centre for Disease Control and Prevention, said mRNA vaccines were being administered to healthy people for the first time and such a roll-out came with risks.
“Western countries adopted the mRNA technology, which was developed for cancer patients,” state news agency Xinhua quoted Gao as saying on Tuesday. “I don’t know whether it will have side effects in the future, but the risk cannot be ruled out.
“There are safety concerns when mRNA vaccines are administered to healthy people for the first time. As professionals, we must have a scientific attitude and analyse the results.”
The mRNA technology tricks the body into making the viral protein itself which, in turn, triggers an immune response, while traditional vaccines, such as most flu shots, use inactivated viruses to set off the immune system.
There have been human trials of mRNA cancer vaccines since at least 2011 but only now has the technology been approved for general use, with regulators in the US and Britain authorising Pfizer-BioNTech and Moderna to distribute their vaccines.
The US and Germany lead the development of mRNA vaccines, while France does not use it because of safety concerns, according to the Pasteur Institute.
China is betting on old and new technologies by developing Covid-19 vaccines in five categories – inactivated vaccines, recombinant (subunit) protein vaccines, live attenuated influenza vaccines, adenovirus vaccines, and nucleic acid-based vaccines.
Safety issues that would affect significant numbers of vaccines mostly appear within two months, according to Michel Goldman, professor of immunology at the Université Libre de Bruxelles in Belgium.
In an interview with the European Union research magazine Horizon, Goldman said that after a vaccine was given to millions of people, very rare unanticipated side effects might develop.
As a result, researchers and regulators would be keeping a close eye on how the vaccine roll-out went, he said.
Gao said China’s three inactivated vaccines were nearing the end of clinical trials and showing good results. Another vaccine – a subunit vaccine, composed of protein or glycoprotein components of a pathogen that are capable of inducing a protective immune response – had also entered the final phase of clinical trials, he said.
“We are not in a race with other countries to produce vaccines,” Gao said. “We are in a race with the virus. We should be united to combat it.”
The official also said China had not found an animal source of the coronavirus.
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“I’ve been to Wuhan to look for the origin in animals and failed to find [the same virus],” Gao said, referring to the central Chinese city where the coronavirus was first detected. “It may take a long time to find the virus. It’s also possible that the virus will disappear before we find the origin.”
Wuhan was ground zero of the pandemic, with the first cases linked to a local wet market selling various exotic animals from peacocks to masked palm civets. Scientists suspect the virus was first carried by an animal host before being transmitted to humans.
A team of 10 international scientists will travel to Wuhan next month to investigate the origins of the disease, the World Health Organization has said.
The US, which has accused China of covering up the extent of the outbreak, has criticised the terms of the investigation, which allowed Chinese scientists to do the first phase of preliminary research.
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This article was first published in South China Morning Post.