Jan. 31 (UPI) -- Chinese health experts say human-to-human transmission cases of the deadly coronavirus in the central Chinese city of Wuhan were occurring in December, although local authorities were ruling out secondary infections at the time.
Beijing News reported Friday researchers from the Chinese Center for Disease Control and Prevention, the provincial Hubei Center for Disease Control and Prevention and other regional bureaus said in a recent study experts agree human-to-human transmissions took place in December.
The Chinese news service was quoting a study published Wednesday in the New England Journal of Medicine, which showed the results of a study of 425 patients in Wuhan.
Human-to-human transmission cases were taking place in December, according to the study.
"On the basis of this information, there is evidence that human-to-human transmission has occurred among close contacts since the middle of December 2019," the researchers said.
"Considerable efforts to reduce transmission will be required to control outbreaks if similar dynamics apply elsewhere."
The Wuhan Municipal Health Committee denied human-to-human transmission was occurring on Dec. 31. It denied human-to-human infections again on Jan. 5 and Jan. 11, and did not change its position until Jan. 16.
"While we have found no evidence of human-to-human transmission, we cannot rule it out," the committee said Jan. 16. "But the risk of persistent human-to-human transmission is relatively low."
Zhong Nanshan, a renowned scientist at China's National Health Commission, confirmed for the first time on Jan. 20 during a Chinese state television interview there is "definite" evidence the virus transmits between people, but the World Health Organization did not declare a global health emergency until Thursday.
Foreign governments are increasingly calling for tighter restrictions against travel.
Japan's Mainichi Shimbun reported Friday Tokyo is moving qualifying matches for the Olympics scheduled for Wuhan in February to other parts of the world, including Amman, Jordan.
Tokyo's Olympic Committee has also been denying rumors on Twitter that claim the 2020 Summer Olympics have been canceled, according to reports.