Staff members check the information of passengers entering China at the Pudong International Airport in Shanghai. Photo: Xinhua

After days of zero new reported cases in Central China's Hubei Province, three asymptomatic COVID-19 infections were reported Friday, including two passengers on board a flight from Russia. 

Experts said occasional imported cases from abroad can be expected and there is no cause for alarm as containment measures are well in place.

The two asymptomatic passengers are Chinese nationals who arrived at Wuhan Tianhe Airport onboard flight CA602 from Moscow, according to Wuhan Health Commission on Saturday. Their final destination was to be Beijing.

The two passengers, aged 18 and 19, are students at universities in Moscow. Their temperatures were normal when they boarded the plane and no symptoms were mentioned in their health declaration upon arrival. 

After passing customs, they were transferred to a local medical observation facility, where they tested positive for the coronavirus, the commission said.

The Chinese Embassy in Russia on Saturday advised caution choosing transit routes from Moscow to China, as the local COVID-19 epidemic situation is still severe, and closed public places such as airports are high-risk areas, the embassy said in its WeChat public account.

Hubei had reported zero new cases of asymptomatic infection in the province for 10 consecutive days before the latest cases.

Authorities and experts reassured the public that sound prevention and control measures are in place and there is no need for concern about a new outbreak of COVID-19.

All crew members and passengers on flight CA602 have been quarantined and tested for the virus, the Global Times learned.

Yang Zhanqiu, deputy director of the pathogen biology department at Wuhan University, told the Global Times on Saturday that as long as the spread of the virus is contained to those on board an aircraft the public should not worry and imported cases can be expected from time to time.

Yang encouraged people not to panic since China's epidemic prevention and control measures, including quarantine upon arrival, are comprehensive and strict.

Xiangyang in Hubei Province also reported on Friday a person returning from elsewhere tested positive for COVID-19 and was diagnosed as asymptomatic. 

The infected person is now in isolation at a hospital, and all close contacts have been quarantined for observation. The Xiangyang government reported that tests of the person's close contacts and samples taken from their living quarters were negative.

The reason why there are more asymptomatic cases and fewer people getting sick is because "the virus is weak" during the summer, Yang said, adding that people should live normally but follow preventative measures.