Shanghai reported one asymptomatic infection on Tuesday, the city's Health Commission told a news briefing.

The case involved an 11-year-old girl who travelled to Shanghai for medical treatment on Friday, and tested negative for COVID-19 on Monday.

She was diagnosed as an asymptomatic case, and is being treated at a local designated COVID-19 hospital.

By 4 pm Tuesday, 98 close contacts and 72 secondary contacts of the case had been identified and quarantined, with 128 of them testing negative so far.

The residence where the patient lived, No 83, Molin road, Jingan district, was classified as a high-risk area, while part of the Nanjing Dong road, Huangpu district was classified as a medium-risk area, and rest of Tianmu Xi road, Jingan district, Yichuan road, Putuo district and Nanjing Dong road, Huangpu district were marked as low-risk areas.

Patients are encouraged to seek medical consultation online, and make medical appointments in staggered schedules.

Considering the current situation, citizens should avoid leaving Shanghai if it is not necessary, and should take proper prevention and control measures, said Wu Qianyu, an official from the Shanghai Health Commission.

"Shanghai will strengthen it's health screening procedures for visitors from risk areas," Wu said.