"When I got the news of the rollout of booster shots in Harbin, I immediately came to the nearest health community center to get a third shot," said a 39-year-old taxi driver surnamed Zhao. "Due to frequent interactions with different passengers, I hope to build stronger immunity against the virus, to protect myself as well as make my passengers feel more secure."

Since mid-September, Tianjin and several cities in the provinces of Fujian, Hainan, Guangdong, Anhui, Hubei and Heilongjiang have announced rollouts of booster shots.

As of Sunday, 40,771 people in Hubei had received an additional shot, China News Service reported on Wednesday.

Key groups in the provincial city Wuhan have been prioritized during the initial stage, such as workers at the Jinyintan Hospital and the airport.

Nationwide, China had administered more than 2.22 billion doses as of Tuesday, according to the National Health Commission.