Authorities on Wednesday reported 16 new Covid-19 cases, among them seven local infections.
Among the latest confirmed patients were those linked to the Tai Hang Tung Estate cluster in Sham Shui Po.
And there were about 10 preliminary cases, several of them related to schools.
After three students at the Delia Memorial School (Broadway) in Mei Foo came down with the virus, a teacher who was present at the exams of one of them has tested preliminary positive.
Dr Chuang Shuk-kwan of the Centre for Health Protection said she found the case “strange” because there shouldn’t have been much contact among people during exams.
She said officials are investigating if it was a super-spreading event.
“Two classes did have spreading events, transmission events in the class. So, we need to be certain how many teachers and students are affected before we can conclude whether there’s a super-spreading event,” Chuang said in a media briefing.
She also said there was an unlinked preliminary case involving a student in St. Joseph’s Anglo-Chinese School in Kwun Tong.
Chuang said he may be linked to the hamster cluster because it appears he has the Delta variant.
But an initial probe showed the student, 17, had not gone to the Little Boss pet shop, or had been in contact with hamsters.
Another unlinked preliminary case involved an air freight worker who mostly works alone at a freight centre at the airport.
He lives in Yat Kwai House of Kwai Chung Estate, the same block where a newly confirmed unlinked case involving a man, 79, also lives.
Officials were checking if they had been in contact with each other.
“We are indeed very worried about the increasing number of unknown cases in the community, with Delta in some cases and Omicron in the other cases,” Chuang said.
“There are signs that there are still cases coming up from the community testing centres, so we urge the public to be vigilant about hand hygiene and avoid social activities as much as possible.”