People receive COVID-19 vaccine at a vaccination site in Gulou District of Nanjing, east China's Jiangsu Province, April 9, 2021.(Photo: Xinhua)

More than 1 billion people in China need to be vaccinated in order to build an immune protection barrier against COVID-19, a senior Chinese immunologist said on Sunday.

"The higher the vaccination rate is, the stronger the immune barrier will be," Wang Huaqing, the chief immunologist at the Chinese Center for Disease Control and Prevention, said in an interview with CCTV.

China is expected to vaccinate 1 billion people, accounting for about 70 percent of its total population, by the end of this year, as the country has entered the fast track of mass inoculation and more producers are joining to meet the vaccine demand, Chinese observers predicted. 

According to past experience, setting up a protection barrier requires 70 to 80 percent of the population to be vaccinated, Tao Lina, a Shanghai-based vaccine expert, told the Global Times.

In practice, realizing a protection barrier is a dynamic process that can be affected by various factors such as the transmission speed of the virus and the vaccine’s efficacy, Tao said.

Feng Duojia, president of the China Vaccine Industry Association, said in a previous media report that time is an important factor for setting up an immune protection barrier. If the vaccination campaign lasts too long and is outpaced by the virus’ transmission speed, the immune barrier will be compromised, Feng said. 

Wang appealed to more people to get vaccinated as soon as possible so that the protection barrier could arrive earlier, and noted that vaccines are now the best option for an early return to normal life.

The continuous spread of the novel coronavirus will allow it to mutate quickly, he noted. The best way to stop the virus from mutating faster is to cut its infection source, which means getting people vaccinated and building up an immunity against the virus.

Addressing concerns that people would still get infected after receiving the vaccine, Wang said that the Phase III clinical trials showed that protection has occurred among the majority of people, and the vaccine mainly protects people from severe illness or death.

"In China, about one in a million people have adverse reactions or severe allergic reactions after vaccination, while the death rate from COVID-19 is 2 percent," Wang noted, adding that vaccines will minimize the risk of infection.

Wang also addressed questions over the safety of the vaccines. The approval for marketing and use indicates that the vaccines have met the basic requirements, despite the fact that the development and research period of the vaccines was short, according to Wang.

China currently has five COVID-19 vaccines approved for conditional marketing or emergency use, and are free for the public' use.

China has set itself a vaccination target of covering about 40 percent of the population by around June, or about 560 million people and 1.1 billion doses.

As of Saturday, 164 million COVID-19 vaccine doses had been administered across the country.