Beijing municipal government holds a news briefing on Thursday, June 11, 2020. (Photo: China Daily)

Beijing reported a domestic COVID-19 case on Thursday, after reporting zero new domestic cases for 55 consecutive days as of Wednesday. 

The patient, a native Beijing man, has been sent to Beijing Ditan hospital, a COVID-19 designated hospital, while two close contacts, both of whom are his family members, have been put under medical observation, the Beijing health authority announced at a press conference. 

The man, surnamed Tang, 52, was discovered Wednesday afternoon as he went to hospital after getting a fever. 

He said he had neither left Beijing nor had close contact with outside people in the past two weeks, according to the authority. 

Pang Xinghuo, vice director of Beijing's Center of Disease Control, said at the Thursday press conference that "the case sounds an alarm for us."

"The case reminds us of the importance, complexity and uncertainty of epidemic prevention and control work in Beijing," Pang said.  

Wang Guangfa, a respiratory expert at Peking University First Hospital, said it is highly likely that the case is related to imported cases. 

The most important thing at present is to trace the virus source of the case and  cut the spread of the virus, Wang told the Global Times on Thursday.

"Although the epidemic situation has stabilized in China, we still have to stay alert, as sporadic cases will still keep occurring here and there," Wang warned.

Beijing health authorities said they had launched an epidemiological investigation into the case to trace the virus source and Tang's close contacts. 

Moreover, they will give COVID-19 nucleic acid tests to all residents in Tang's community. 

They will also collect environment samples from places Tang had been to in the 14 days before the onset and samples from people in these places, and investigate people living in Tang's community who had just come to Beijing in the past month.

Management in communities, office buildings and public places on the street Tang lives will also be enhanced, according to the authorities. 

Jin Dongyan, a professor at the School of Biomedical Sciences at the University of Hong Kong, told the Global Times on Thursday that it's not surprising to see such cases, as similar cases have been reported in places like Hong Kong and Taiwan. 

"It's likely that Tang was infected by some asymptomatic carriers of COVID-19 when he was outside his home. Sporadic cases like this kind may continue to occur in the future, and it conforms to the transmission rule of COVID-19," Jin said. 

Jin said that the case reminded both the government and residents to stay on high alert, and at the same time, the Xicheng district government needs to expand nucleic acid tests to more residents who live close to Tang.

Tang's symptoms include feeling highly sensitive to the cold and lacking strength, but he had no cough, sore throat or chest distress, the Beijing health authority said.   

Tang rode a bike to the hospital to see the doctor on Wednesday and wore a mask the whole way, the authority noted.