BEIJING, May 17 (Xinhua) -- More targeted and effective measures should be carried out to step up the screening, isolation and hospitalization of COVID-19 patients amid efforts to avert rebounds of the domestic epidemic, a Chinese health official said Sunday.

The nine new confirmed cases reported on the Chinese mainland over the last three days were all from close contacts under medical observation, said Mi Feng, spokesperson for the National Health Commission, at a press conference.

In more positive developments, the number of asymptomatic cases under medical observation on the mainland had been declining for 15 straight days, and all COVID-19 patients reported in northeast China's Heilongjiang Province had been discharged from hospital after recovery as of Saturday, Mi said.

The number of patients still hospitalized by Saturday fell to 86 on the mainland, the commission said in its latest daily report.