Containment of the illness has been a struggle far from the epicenter in central China as a major South Korean city urged residents to stay indoors.

New infections in China have been falling for days, although changes in how it counts cases have caused doubts about the true trajectory of the epidemic.

"The downward trend will not be reversed," Ding Xiangyang, deputy chief secretary of the State Council and a member of the central government's supervision group, said on Thursday.

China's figures for the previous 24 hours brought the total number of cases to 75,465. The 118 newly reported deaths raised the total to 2,236. More than 1,000 cases and 11 deaths have been confirmed outside the mainland.

Iran announced three more infections Thursday, a day after it reported its first two deaths, and South Korea reported its first fatality. Japan said two former passengers of the Diamond Princess cruise ship had died of the illness.

In Australia, two people who were flown back home after the 14-day quarantine on the Diamond Princess ended tested positive for the virus despite clearing multiple screenings before the flight.

"It's possible more people could develop positive tests over the next few days," said Australian Chief Medical Officer Brendan Murphy.

The two new cases take the total number in Australia to 17. Of those, 10 people have recovered. Some 170 Australian passengers, most aged in their 60s and 70s, will be quarantined for an additional two weeks after leaving the Diamond Princess.

China last week had started recording new cases without waiting for laboratory results, causing a significant spike in the number of cases. But on Thursday it returned to its prior way of counting, and removed some cases from the tally because lab tests came back negative.

The changes are sure to aggravate observers who say consistency is key to understanding COVID-19's path.