The head of China’s Centres for Disease Control and Prevention has said the efficacy of the country’s Covid vaccines is low, in a rare admission of weakness.
In a press conference, Gao Fu said the current vaccines “don’t have very high rates of protection” and suggested that China was considering mixing Covid-19 vaccines to boost efficacy.
China has developed four different vaccines approved for public use, though some trials abroad had suggested efficacy as low as 50%.
Mr Gao explained that steps to “optimise” the vaccine process could include changing the number of doses and the length of time. He also suggested combining different vaccines for the immunization process.
But he later appeared to backtrack on his comments, telling state media Global Times that “protection rates of all vaccines in the world are sometimes high, and sometimes low”.
“How to improve their efficacy is a question that needs to be considered by scientists around the world,” he told the paper.
He added that his earlier admission that Chinese vaccines had a low protection rate were a “complete misunderstanding”.
Mr Gao’s original comments were withdrawn by state media after criticism.
How Chinese vaccines work?
China’s vaccines though differ significantly from some vaccines, especially those developed by Pfizer and Moderna.
Developed in a more traditional way, they are so-called inactivated vaccines which means they use killed viral particles to expose the immune system to the virus without risking a serious disease response.
By comparison, the BioNtech/Pfizer and Moderna vaccines are mRNA vaccines. This means part of the coronavirus’ genetic code is injected into the body, training the immune system how to respond.
One significant advantage of the Chinese vaccines is that it can be stored in standard refrigerators at 2-8 degrees Celsius. Moderna’s vaccine needs to be stored at -20C and Pfizer’s vaccine at -70C.
China is offering its vaccines around the world and has already shipped millions to countries from Indonesia, Turkey to Paraguay and Brazil.
More than 100 million people in China have received at least one shot of the vaccine. Beijing insists the jabs are effective and said it will grant visas only to foreigners with a Chinese shot.