But he said the formulation of vaccines for children will be different from the ones for adults, so the government will need to order a new batch of vaccines if it decides to let children under 12 take the jabs.

A primary school principal believes students in senior primary forms will be interested in getting the vaccine.

Chui said American pharmaceutical company Pfizer has administered one-third of the dosage of the BioNTech vaccine to more than 3,000 children aged five to 11 and found it to be safe and effective for kids.

"The efficacy has reached 91 percent, which is the same as adults," Chui said, adding none of the 3,000 children had myocarditis - an inflammation of the heart muscle.

But he said the study found some children experienced symptoms including pain at the site of vaccination and headaches, and suggested children should take a half-day rest after inoculation.

Chui said children should only get one-third of the original dosage of the vaccine as they have a lower body weight and a more active immune system.

"But the SAR will need to purchase another batch of vaccines designed for children," he said, as vaccines for children have different assistive components.

"I believe the government is asking pharmaceutical companies about BioNTech jabs for children aged five to 11."

But it is uncertain whether Hong Kong will be able to obtain the jabs within two months because the Food and Drug Administration in the United States just started to review the vaccines yesterday and other countries around the world are also snapping up the jabs, he said.

As for mainland-made Sinovac jabs, Chui said the vaccine has a 60 percent protection rate among those aged three to 17, which is enough to protect them.

Honorary chairman of the Aided Primary School Heads Association, Langton Cheung Yung-pong, said that vaccination for children is "inspiring," but whether students will get the jab depends on their parents.

"Parents of primary five or six students would like to let their kids get the jab so that they can study for a longer time at schools, but parents of younger students may not have enough confidence in the jabs," he said.

Cheung said it's hard to say how many primary schools can resume full-day classes and the government should provide more vaccine information to parents.

Meanwhile, the Department of Health has received applications from Sinovac to lower the age requirement for its Covid-19 vaccine from 18 to three in Hong Kong. The application will be reviewed by experts.

Currently Hong Kong is offering the Beijing-made Sinovac vaccine to those aged 18 or above and the German-made BioNTech one to those 12 or above.

The Centre for Health Protection yesterday said 95 percent of Covid-19 cases since May were imported, while local infections remained at "a very low level."

Meanwhile, Hong Kong yesterday recorded three imported cases from Singapore and Pakistan, taking the SAR's tally to 12,331 cases, with 213 deaths.

All of them have been vaccinated and two carried the L452R mutant strain present in the Delta variant.