Government pandemic advisor Ivan Hung said on Saturday that there may be a slight rebound in Covid cases this summer, and that elderly people should therefore plan to have a booster before then.

His comments came after the government announced that from April 20 it will only offer free Covid booster jabs to high-risk groups, including people aged 50 or above and healthcare workers,

Hung said the decision was based on the World Health Organisation's updated recommendations, as it no longer advises non-high risk individuals to get booster jabs.

He added that it was appropriate to require healthy individuals who are already triple-jabbed to pay for an extra shot.

"I believe this won't lower people's intention to get a booster," he told reporters. "For low-risk groups, if they need an extra jab – for example, some may think there's a higher infection risk when they go travelling – I believe they are able to pay for the booster."

But he advised elderly people to get a booster if they received their last dose more than six months ago, as he predicted there would be a slight rebound in Covid cases in the summer.

Hung also said that other upper respiratory diseases, such as flu, had become more common after the SAR scrapped its mask mandate rule.