(Yicai Global) Dec. 21 -- There have been no severe side effects in the more than one million people who have received the Covid-19 jab since July and results show that protection is conferred for at least half a year, officials from the National Health Commission said.

China started emergency use of novel coronavirus vaccines in June to protect high-risk populations, Zheng Zhongwei from the NHC’s Development Center for Medical Science & Technology said on Dec. 19. Over 60,000 people who received the jab have since traveled to high-risk areas outside of China and none of them have come down with the disease, demonstrating that the period of protection is at least six months.

Another 75,000 overseas volunteers have been inoculated with two vaccine candidates developed by the China National Pharmaceutical Group and one by Sinovac Biotech in Phase III clinical trials and there have also been no serious adverse reactions, he said.

“It is not yet possible to know how long the vaccine will offer protection for,” said Deputy Director Zeng Yixin. Based on Phase I and Phase II clinical trials that started in March, it will be valid for more than half a year, he added.

The flu vaccine is given once a year because the flu virus mutates very quickly. It does not mean that the duration of immunity is just one year, Deputy Director Cao Yixin said. It should not be necessary to revaccinate for Covid-19 every six months or one year, he added.

Common side effects observed from earlier Covid-19 vaccine candidates were headache and fever, cough, loss of appetite, vomiting, diarrhoea and local redness and swelling at the injection location, said Jiao Yahui, a NHC inspector.

Editor: Kim Taylor