A leading epidemiologist on Tuesday called on the authorities to improve the monitoring of Covid-19 cases ahead of a likely increase in summer, though he said flu posed a bigger threat to public health at the moment.

Benjamin Cowling of the University of Hong Kong's School of Public Health made the comments on RTHK's Hong Kong Today programme, saying better surveillance would help officials assess the likely level of demand for healthcare.

"For flu, we have a well-established surveillance system for many, many years that we can look at on the website, and the government look at all the time to see when flu cases are going up and when they're coming down again," he told RTHK's Samantha Butler.

"For Covid, we're still in the early days of having a similar surveillance system, because until quite recently there was just a lot of testing and we were counting the confirmed cases.

"So we need to sort out the best way to do Covid surveillance so that at least we can track the progress of infections and the level of infections in the community."

He said the severity of Covid infections had come down in the past couple of years, mostly because people had some immunity from prior infections or vaccinations.

Cowling also said people could make up their own minds about whether they want to get a Covid vaccine, although it's recommended for high-risk groups, such as the elderly or chronic patients.

The academic noted that Hong Kong appeared to be at the start of what could be a large flu season.