The country managed to control local transmission through firm lockdowns after the virus first emerged in the central city of Wuhan late last year.
But a new surge has been driven by infections in the far-western region of Xinjiang.
Mainland China reported 105 new coronavirus cases in the mainland for July 29, up from 101 cases a day earlier, officials said.
Of the new infections, 96 were in the far western region of Xinjiang, five were in the northeastern province of Liaoning, one was in Beijing, and three were imported cases, according to a statement by the National Health Commission.
China also reported 21 new asymptomatic patients, down from 27 a day earlier.
As of Wednesday, mainland China had 84,165 confirmed coronavirus cases, the health authority said.
The Covid-19 death toll remained at 4,634.
Concerns are mounting about China facing a second wave of the deadly disease.
The Xinjiang region has begun mass testing and introduced quarantine measures due to the spike of infections, the Express reports.
The current outbreak in Liaoning, which began on July 22, centred mostly on the port city of Dalian, east of Beijing.
The first case in Dalian worked at a seafood processing company and had not travelled out of the city in recent weeks.
To contain the spread of the virus, Xinjiang and Dalian have tested millions of people for Covid-19, but the coronavirus is already believed to be spreading.