About 200 million doses of COVID-19 vaccine have been administered so far inside China, with an emphasis on frontline workers, university students and people living in border areas, health officials say.
China is ramping up vaccination efforts after a slow start that was due in part to the virtual elimination of domestic transmission of the coronavirus.
Just two local cases were reported on Wednesday, both in the city of Ruili, which borders Myanmar.
China has approved five domestically produced vaccines and exported millions of doses, although some scientists believe they provide less protection than those by Pfizer, Moderna and AstraZeneca.
The Chinese vaccines have an efficacy range of 50.7 per cent to 79.3 per cent, based on company data, lower than their foreign peers but still effective.
It was not immediately clear how many people had received both their first and second shots of vaccine.
"At present, vaccination efforts in key areas and key population groups are progressing smoothly overall," Cui Gang, an official with the Center for Disease Control, told reporters at a news conference on Wednesday.
Already, 80 per cent of workers in the health sector had received at least one injection of vaccine, Cui said.
Cities across China had reported shortages, with some people saying they could not get an appointment to get a second dose, National Health Commission spokesman Mi Feng said.
Health officials acknowledged the difficulties and said local governments should aim to make sure the second shot was provided within eight weeks.
China is giving millions of shots a day, and its goal is vaccinating 560 million of the country's 1.4 billion people by mid-June.
Australian Associated Press