“We need to be patient and then we need to wait for a formal recommendation of the government… as [to] what we will do because they need to decide when is safe to give the third dose and what kind of vaccine should be used after the second dose,” Leung said.
He was speaking after a media report about a man who supposedly received two Sinovac jabs in Beijing in February, before getting a BioNTech jab in Hong Kong in June.
Leung said people should not follow suit and mix vaccines.
“Up to now, we don’t have… published data on the effect and also safety of mixing different vaccines,” he said.
Leung noted that although one’s antibody level may decrease over time after vaccination, there is an “immune memory” which continues to protect them from serious illness.
Government advisers have said they will consider if people need booster shots around autumn, when more international statistics become available.