At least a quarter of imported infections could have been missed at the airport's Covid-19 tests due to potential "false negative" results, according to Polytechnic University researchers.

Analyzing local virus strains, the team found that at least 25.2 percent of the 286 imported cases between September 1 and October 31 were only detected during their mandatory quarantine. That means some inbound travelers might have passed the nucleic acid tests at the airport despite being infected.

Gilman Siu Kit-hang, associate professor of health technology and informatics and the leader of the research team, said the airport tests might not be able to pick up patients with low viral loads, usually seen in the first few days of infection.

Siu also said that the rate of these false negativity cases is alarming.

"To my surprise, the figures were a bit high. I thought it was only a few percent the percentage could be even higher," he said.

He pointed out that the real-time reverse transcription-polymerase chain reaction test deployed at the airport cannot identify patients with a viral load of fewer than 250 copies per milliliter.

With the pandemic still raging, he is worried incoming passengers could spark a fourth wave of infections.

He said a genetic sequencing analysis in confirmed cases showed that the recent clusters - including the China Secret bar, the Royal Garden Hotel and the Mui Wo staycation clusters - might have been triggered by imported cases from Nepal and India.

"I don't think the fourth wave has started, but it might be coming," Siu said. He said recent cases belonged to a new virus strain and that while there had been an increased number of imported cases since late September, there hadn't been a surge in infection numbers.

Siu said visits by family or friends to those quarantined in hotels, which might be a loophole in quarantine measures, could have contributed to community outbreaks in recent months.

During a recent visit to a hotel that had seen several confirmed cases, Siu said he could enter freely without being intercepted by staff.

"I just pretended to visit my family... I [didn't] encounter any problems.

"I just went inside and nobody questioned me. I could get into the elevator and to the hotel room and then go back," Siu said.

He urged the government to establish designated hotels for quarantine in which visits are not allowed and where health officials would be stationed. Travelers should also use designated transportation when heading to quarantine locations.

Separately, the University Grants Committee will allocate HK$50 million to the eight UGC-funded universities to strengthen their student support services in response to challenges arising from the pandemic.

The universities will take forward various supporting initiatives, encompassing psychological counseling, mental well-being and career planning and development, as well as physical fitness and a healthy lifestyle, to take care of the various needs of students.

Virus gatekeeper fears for airport