Shanghai reported 983 new COVID-19 infections on Wednesday, with 979 of them being asymptomatic, the city's health authority announced on Thursday.

Wu Jinglei, director of municipal health commission, told a news conference that 81 hospitalized COVID patients have been discharged from the hospital after recovering and 230 asymptomatic cases have completed their medical observation period.

"Some communities in Shanghai are still undergoing grid quarantine and testing," he said, adding that the city is still at a critical stage of curbing the spread of the virus.

Zhang Wenhong, head of the infectious disease department at Huashan Hospital, wrote on his Weibo account on Thursday that the current strategy adopted by the city is aimed at breaking the transmission chains by rotating grid testings and lockdowns of areas with higher risk exposure to the virus.

"Statistics have shown that new infections among people not in quarantined areas now account for around 10 percent of the total, which is a sign that the current outbreak is gradually coming under control," he said. "Although we've not reached the peak, the conditions for a turning point are taking shape."

Li Rui, vice-governor of Minhang district, where two villages were elevated to medium-risk areas on Thursday, said the local government is doing its best to ensure the supply of food and medicine to residents.

"We've given testing priority to essential workers of e-commerce platforms so as to put them back in their posts. We've coordinated with private and State-owned companies to guarantee a sufficient supply of resources," he said. "We've also taken special care of the vulnerable population, including the disabled, the unemployed and elderly people are who living alone."

Li said the Shanghai No 5 People's Hospital has been designated to treat patients from quarantined areas, and that the district has deployed 40 vehicles to carry out closed-loop transportation for patients.