The No 1 and No 2 section of Linjiang Xincun residential neighborhood in north Shanghai's Baoshan district was categorized as a medium-risk area for the spread of the COVID-19 virus on Saturday, bringing the total of such areas in the municipality to three, according to the city government.

Two of the new COVID-19 confirmed cases reported on Friday lived in one of the sections and had been to the other over the past two weeks before they were diagnosed. They are the parents of a confirmed case from the previous day and were found through tracing close contacts of confirmed patients.

The other two medium-risk areas in the city are Zhaotong Road residential neighborhood in downtown Huangpu district, which was announced on Thursday, and the Salvo Hotel Shanghai, which was announced on Friday. The hotel is about 200 meters away from the residential neighborhood.

Wu Jinglei, director of the Shanghai Municipal Health Commission, also emphasized that a confirmed case reported on Friday is a professional piano player and his schedule in Shanghai before being diagnosed mainly involved practicing the instrument in piano rooms.

"The information that went viral on the internet identifying the case as a piano teacher who had tutored over 100 children is fake," he said at a municipal news briefing on Saturday.

He added that 434 individuals in Shanghai identified to be related to the case, including 82 close contacts, tested negative for the COVID-19 virus in their first tests.

All current nine locally transmitted patients are mild cases and are in stable condition, Wu said.

The six cases reported on Thursday were two hospital workers, two hotel workers, a resident at the same hotel, and a relative of one of them. The third case reported on Friday, the pianist, was a friend of a confirmed case reported on Thursday and lived at a hotel in Huangpu district.

"The nine local cases in this wave so far are interconnected," Wu said.

He also refuted online rumors that some districts in Shanghai are or will soon impose mass nucleic acid tests on all residents.

The health authority also reminded the public not to panic if disease prevention workers wearing protective suits appear in their neighborhoods.

The reason for their appearance in neighborhoods or shopping malls can be varied, Wu said. "They are there perhaps to conduct further investigation of someone with a suspected nucleic acid test result, to locate a close contact of a case, to collect samples from the environment for lab tests, or to disinfect a public venue."

"Their appearance is to safeguard public health in the city and to run against time to stop the virus' spread," he said.

Yin Xin, a spokeswoman with Shanghai municipal government, said that in regard to students' health and safety, school instruction for children and teenagers has moved online.