vaccine Photo:VCG

COVID-19 vaccines are able to protect people from infections for more than half a year, but whether people can achieve life-long or 5-10 years immunity via vaccination is not yet certain, said a senior Chinese health official on Saturday.

Some findings from animal tests, clinical trials and medical follow-ups with discharged patients indicate that there is basically no doubt over the protection period of more than half a year, Zeng Yixin, a deputy director of China's National Health Commission, said during a press conference.

Animal tests that began from February show monkeys, which had been vaccinated and then attacked with coronavirus, have been protected sufficiently from being infected by the coronavirus.

Moreover, antibodies are still present in subjects who attended the Phase II clinical trials launched in March. Medical institutions' follow-ups on recovered patients found antibodies present for up to 10 months in some patients, Zeng said. 

Zeng holds an optimistic view that people don't have to receive COVID-19 vaccines every six months or a year like flu vaccines.

The immunity caused by the coronavirus is not durable, so the COVID-19 vaccine cannot make someone immune for life, a Beijing based expert on immunology told the Global Times.

"Coronavirus is a common cold virus, like rhinovirus and adenovirus, which are less threatening pathogens. The human immune system will not be permanently immune to such viruses," he said, adding "That's why people catch colds repeatedly."

The immunity period depends on the characteristics of the virus' genes, experts said. 

The "human body's immunity for the flu virus is generally about one year, so we have to get the vaccine every year, but for the polio virus, the body can form a lifelong immunity," Yang Zhanqiu, a deputy director of the pathogen biology department at Wuhan University, told the Global Times.

It is generally believed that human body's immunity to novel coronaviruses, including other coronavirus infections, could last for two to four years, therefore people may need to receive vaccines against COVID19 again two to three years later, Yang said.

China announced on Saturday it will give key populations COVID-19 vaccines in winter and spring, aiming to build up herd immunity, and include more in the program afterwards.

So far, more than 1 million doses of COVID-19 vaccines have been administered in China as the country kicked off vaccinations for emergency use in July, and no severe adverse reactions have been reported, China's health authority announced at the conference.