China has approved its fifth Covid-19 vaccine, made from hamster ovary cells.
The vaccine was developed by Anhui Zhifei Longcom Biopharmaceutical Co. and the Chinese Academy of Sciences. It was developed by a team led by George Gao, head of the Chinese Center for Disease Control and Prevention.
The Chinese Academy of Sciences said in a statement on Tuesday that the Chinese government gave the injection authorization for emergency use on March 10. This is the fourth vaccine that China has approved for emergency use after two vaccines made by Sinopharm, a state-owned vaccine manufacturer and one developed by Sinovac, a private Beijing company. It also approved a fifth vaccine, made by the Chinese company CanSino Biologics in partnership with the military, for general use.
Neither the company nor the institute behind the last vaccine to be approved has published efficacy data from its Phase 3 tests, which are taking place in China, Ecuador, Indonesia, Pakistan and Uzbekistan.
Uzbekistan has approved the vaccine. The Chinese Academy of Sciences said that Phase 3 clinical trials, which involve 29,000 volunteers, are “progressing smoothly.”
In Phase 1 and 2 tests in China, the Chinese Academy of Sciences said, there were no serious adverse reactions among the volunteers and the vaccine produced neutralizing antibodies at levels equivalent to those of other coronavirus vaccines. These results have not been peer-reviewed.
The vaccine manufacturing process begins when the genetic code for the coronavirus spike protein is placed in the cells of the ovaries of hamsters, commonly subjects of medical research.
The cells begin to produce the protein and, when they reach a considerable volume, are harvested and purified. The vaccine is completed with an adjuvant, an ingredient that strengthens the immune system.
The Chinese Academy of Sciences said that vaccine production could easily be expanded in China and elsewhere, and that it would be convenient for storage and transportation.
But the vaccine has several disadvantages. One is that it does not produce many T cells, which help to clear infected cells and prevent them from spreading.
Without these cells, a person’s antibody levels may not be high enough to clear the infection, said Ooi Eng Eong, professor of microbiology and immunology at the National University of Singapore. “You are more likely to get an invasive infection,” he said.
Elsie Chen contributed research.