China could basically achieve herd immunity against COVID-19 by early 2022, said a top Chinese health expert, as the world's most populated country speeds up its vaccine roll-out.

"I hope that China's vaccination rate could reach 70 percent to 80 percent by early 2022 or even by the end of 2021, thus basically achieving herd immunity," said Gao Fu, director of the Chinese Center for Disease Control and Prevention (CDC).

Due to the nature of the virus, the country is now aiming for a vaccination rate of 70 to 80 percent based on the basic transmission index for the novel coronavirus, Gao said.

China has already launched a massive COVID-19 vaccination campaign. As of midnight March 20, the country had administered nearly 75 million doses of COVID-19 vaccines, the National Health Commission (NHC) said.

254 million people aged above 60 to get inoculated

At present, China has started vaccinations for people aged above 60, aiming to reach nearly 254 million seniors.

"Some areas have started vaccinations for people over 60 who are in good health and we will launch a mass inoculation program for this age group as soon as we have sufficient data from clinical trials," said He Qinghua, an inspector at the Bureau of Disease Prevention and Control of National Health Commission, at a press conference held in Beijing on Sunday.

Initially, only people aged between 18 and 59 can get COVID-19 jabs based on the safety and efficiency data collected by clinical trials. However, the data released by NHC showed that people aged 60 or above are the most severely damaged group as more than 80 percent of the death cases are those aged over 60.

"So far, we haven't detected any abnormalities related to the Sinovac's vaccines," said Liu Peicheng, spokesperson for Sinovac Biotech Ltd, adding that the company's vaccines have been approved for use in mass vaccinations in nearly 30 countries including Chile, where the eldest firstly take vaccinations.

With more data showing safety and efficiency of the vaccines on elderly people, more and more elderly people are expected to be inoculated with the vaccines and free from being infected with the virus.

Confidence in vaccines urged

Days ago, a man in northwest China's Xi'an City was infected again after having received two shots of the vaccine, raising questions about the vaccines' efficiency.

"As for the efficacy of the vaccine, it protects most people, especially from severe symptoms. For some individuals, it may fail to have its due effect, especially in the case in Xi'an," said Wang Huaqing, chief scientist for the Immunization Plan at CDC, adding that they will further study and investigate the reason for this incident.

On March 15, the ZF2001 vaccine, jointly developed by the Institute of Microbiology of Chinese Academy of Sciences (IMCAS) and Anhui Zhifei Longcom Biopharmaceutical, was approved for emergency use, making it the fifth approved vaccine.

"The vaccine has a simple composition, which helps it avoid possible side effects caused by other ingredients," said Gao, adding that the vaccine's early and mid-stage clinical trials prove good, and the ongoing late-stage also shows good results.

"This is the first time in human history with COVID-19 vaccine inoculations, so there are no scientific evidence showing which vaccine is the best," said Gao, urging people to have confidence in vaccines since they are the ultimate protection against the virus.