A local resident receives a polymerase chain reaction (PCR) test at a street sample collection site in Shanghai.

All travelers to Shanghai from other provinces must receive a daily nucleic acid test for three days in a row, otherwise their health code will turn yellow, according to the city's big data center.

They are required to receive the first test within 24 hours upon arrival, Shao Jun, director of the center, told the city's COVID-19 press briefing on Monday.

The new measure aims to strictly prevent infections from outside Shanghai and further enhance the city's COVID-19 prevention and control capabilities, Shao said.

A yellow code is for discharged confirmed or asymptomatic cases who are still under home quarantine, risky groups screened out by inter-provincial data research, and those who failed to take part in the city's polymerase chain reaction (PCR) screening for a week.

Shanghai has reported some 120 COVID-19 positive cases since October 1, the beginning of the weeklong National Day holiday, mainly travelers from other provinces and their close contacts, according to the city's health commission.

To curb the spread of the coronavirus, all public culture and entertainment venues in Changning and Putuo districts were closed from Monday.

The sites include all singing and dancing halls, internet bars, game centers, chess and poker rooms and role-playing mystery games.