Two Department of Health scientific committees held meetings on Wednesday and recommended Secretary for Food and Health Sophia Chan Siu-chee roll out third jabs for priority groups.

One of the experts David Hui Shu-cheong from the Chinese University of Hong Kong said those having completed both doses of the Beijing-made Sinovac vaccine can take the German-made BioNTech/Fosun shot as a booster as studies have suggested mixing the two brands could generate more antibodies.

But those who had taken BioNTech as their first two doses should stick with the brand for the booster jab.

Hui said priorities should be given to senior citizens above 60 and high exposure groups including medics, cross-border drivers, as well as workers at the airport, designated hotels and care homes.

He suggested citizens receive the third dose at least four weeks after their first two, and if they also plan to take flu jabs ahead of the winter flu peak season, they should keep the shots at least two weeks apart.

The decision came after earlier studies found that the level of antibodies detected in citizens' bodies plummets significantly over time.

Experts from the World Health Organization earlier advised elderly aged 60 or above who have completed the Beijing-made Sinovac vaccination course to get a third dose as a booster jab.

The latest guidelines in the mainland have also advised those aged 18 or above to get the booster jab six months after their second shot.