The health chief of Hong Kong said the city had "probably entered into a new wave of cases" of coronavirus infection on Friday (Nov 20) and authorities would ask more students to stay home.

Asia's financial hub has confirmed 26 new cases of coronavirus, 21 of which are locally transmitted, Food and Health Secretary Sophia Chan said at a briefing.

She did not include a breakdown of cases that were untraceable.

"We certainly have reached a new wave of cases," she said.

"On Friday, Hong Kong also had over 30 preliminary positive cases," Ms. Chan said.

Due to upper respiratory tract infection outbreaks and Covid-19 fears, authorities will suspend in-person classes for primary school levels 1-3 beginning on Monday for two weeks, and will not rule out stopping classes at all schools if the situation gets worse.

Due to upper respiratory tract infections, the decision came just over a week after kindergartens were forced to close for a fortnight, RTHK said.

Ms. Chan expressed concern that infection control measures already in place have failed to prevent new outbreaks, especially with the emergence of a new wave.

"As the transmission routes of upper respiratory tract infections and Covid-19 are similar, if Covid-19 spreads at schools, the risk posed to the community is very high," she said.

"An examination will take place at a later date to assess if there is a need to extend the class suspensions. If the situation worsens, the authorities have not ruled out suspending all classes at primary and secondary schools," Ms. Chan said.

As the situation was "deteriorating rapidly" the Health Secretary called on the public to be alert, urging them to avoid unnecessary gatherings.

Taxi drivers and home care staff will be forced to undergo Covid-19 compulsory testing, as will patients who show symptoms while visiting doctors, RTHK said.

The government is considering awarding grassroots workers a one-off subsidy if they are reported to have been contaminated.