She said during a radio programme that most of the diners at the Moon Palace restaurant on Monday afternoon, around the same time as a Cathay Pacific aircrew worker who ate there, were already found, with the eatery tracking down some customers who used credit cards.
The Cathay employee is understood to have spread the variant to at least three diners.
“Obviously there were some people who didn’t book a table but walked in, so therefore I think they are still finding those people,” Chan said.
The health chief said the government does not have access to people’s data on their LeaveHomeSafe app, and called on diners who received a notification on the app to get in touch.
“There are some people who actually have come forward and called the hotline… so most of the majority of these people have been found, but we obviously would like to appeal to the public, for those of you who have been [to Moon Palace] and not yet been found to come forward.”
She said the Cathay crew member was sitting at a table close to the restaurant’s entrance, and others might have caught the virus when they walked past his table.
Yuen Kwok-yung, a government advisor on the pandemic, said diners should have worn their masks entering or leaving the restaurant, so poor ventilation was more likely to blame for the transmission of the virus.
He told a television programme that the air purifiers installed on the restaurant’s ceiling might not be able to facilitate air circulation, adding that the number of air changes was fewer than the required six times per hour.
But Yuen said it is too early to say if it was a super-spreading event at the restaurant at Festival Walk, and Hong Kong can still avoid a big outbreak if all efforts are made to identify any Covid patients.
He called on the authorities to step up their contact-tracing abilities with the help of technology, like bluetooth, adding that privacy should take a backseat in the face of new and dangerous viruses.
Meanwhile, the health minister said authorities will be discussing with sectors involved in the expanded vaccine bubble before the policy is implemented by Chinese New Year.
People who want to go to places such as restaurants, libraries, beauty salons and gyms will need to have had at least one dose of Covid vaccine.
“As far as other places are concerned, such as those with high risks, that would be the next step,” Chan said.
Government advisor Ivan Hung said earlier more venues, such as wet markets, should be made off-limits to those who haven’t had a jab.
Separately, another government pandemic adviser, David Hui, said plans to open the border with the mainland are not likely to be affected if there’s no fifth Covid wave by next Sunday, 14 days after the diners were infected at Moon Palace.