SHANGHAI -- Though data for COVID-19 infections in Shanghai continue to fluctuate, the daily number of people testing positive has been on a downward trend, local authorities announced Tuesday.

Most of the new cases were detected in concentrated quarantine facilities or areas under closed-loop management, the municipal disease prevention and control center told a press briefing.

Shanghai has divided the whole city into closed-off management areas, restrictive control areas, and prevention areas to mitigate and control spread. The first two types are under closed-loop management.

The megacity, home to 25 million people, reported 1,661 confirmed locally transmitted COVID-19 cases and 15,319 local asymptomatic carriers on Monday, the municipal health commission said Tuesday.

Of the newly confirmed infections, 968 had previously been reported as asymptomatic carriers, the commission said in a statement.

A total of 675 confirmed cases and 15,120 asymptomatic carriers were detected through testing of the city's residents under quarantine, while the remaining cases were found during screenings of at-risk groups, it said.

According to the commission, the city registered 52 COVID-19-related deaths on Monday. The oldest among the deceased was 100 years old and their average age was 83.1. All the 52 patients had serious underlying health conditions.