Medical workers administer COVID-19 vaccines to college students in Nanchang, capital of east China's Jiangxi Province, June 4, 2021. A temporary vaccination site is newly set at a stadium, with daily inoculation capacity of about 5,000. Photo: Xinhua

Half a year after the start of mass vaccination in China, researches are planning on giving recipients a booster dose to enhance protection.

The Global Times learned the disease control and prevention authorities in East China's Jiangsu Province (Jiangsu CDC) are conducting clinical trials on a booster injection. It comes amid roaring discussions over the necessity of a booster shot half a year after the beginning of the inoculation drive - a timing some experts consider proper for giving additional injection. 

Booster shots will be provided to more people who have already taken the vaccine. China has administered more than 820 million shots of COVID-19 vaccines as of Wednesday, according to the National Health Commission. 

An official with the Jiangsu CDC confirmed to the Global Times on Thursday that clinical researches on the booster shot are being carried out in the province involving CanSinoBIO's vaccine, without providing more details. 

According to information published on clinicaltrials.gov, researchers in Jiangsu launched the trial in May. 

A total of 300 healthy volunteers aged 18-59 years who have accepted at least one dose of inactivated vaccines will be recruited in the trial. They will be divided into two groups to receive a booster dose of inactivated vaccine or recombinant vectored vaccine 3-6 months or 1-3 months after their first dose. The occurrence of adverse events within 28 days and serious adverse events within six months after vaccination will be observed, according to the website.

About one month before the launch of the trial, Gao Fu, head of China's CDC, had revealed at a forum that Chinese authorities were studying on booster shots to enhance vaccine's protection for recipients.  

China kicked off mass vaccinations on December 15, 2020. 

It is proper to administer a booster vaccine dose "after 6-12 months" following normal vaccination procedure to enhance protection against the virus, a Beijing-based vaccine expert told the Global Times under the condition of anonymity on Thursday. 

The expert believes that booster shots will be provided to more people receiving vaccines in the long run. Similar to previous mass inoculation, the booster dose vaccination may also start with high-risk groups including medical workers and border inspection staff, he said.

The anonymous expert said it is better to give a booster shot developed using the same technique as the previous shots the recipients got, but Tao Lina, a Shanghai-based vaccine expert, believes that mixture of shots of different techniques will be safe and effective. 

"Possible side effects and adverse reactions would be very limited," Tao said, noting that experiments of mixing vaccines conducted overseas could also serve as reference for China, where booster injection is not an urgent issue as the epidemic is under effective control. 

CanSinoBIO and another Chinese producer Sinovac have already conducted trials on booster shots. The results showed antibody levels of recipients increased by more than 10 times after getting the booster shots in six months after finishing normal vaccination procedure. 

Ren Chao, a Wuhan-based volunteer who received the CanSinoBIO vaccine in March 2020 and then a booster shot in September, previously told the Global Times that his personal antibody level increased more than 20 times after the booster dose.

Ren said his sense of security dramatically increased after the booster shot. "I feel I am no longer afraid of COVID-19 at all," he said.