A study by the University of Hong Kong (HKU) has suggested that men and young adults are more prone to myocarditis – or inflammation of the heart muscle – after taking a second dose of BioNTech vaccine, even though the probability of that happening is still extremely low.

The research was based on a big data analysis which tells scientists the side-effects of Covid jabs for different groups of people.

Speaking at a press conference on Tuesday, researchers said people who are double jabbed with the BioNTech vaccine are 10 times more likely to develop heart inflammation compared to those who are unvaccinated.

In particular, they said men and people aged under 30 are more at risk.

But Francisco Lai, a research assistant professor from the university's Department of Pharmacology and Pharmacy, said the benefits of getting jabbed still substantially outweigh the risks.

"We should highlight that these kinds of adverse events are still very rare. Even [if] we're using big data to do our research, we only identified a very rare incidence. So we do think overall the safety is good," he said.

"The risks of getting Covid-19 and its related complications actually far outweigh the possible rare adverse events brought by vaccination."

Meanwhile, another HKU professor at the Department of Pharmacology and Pharmacy, Esther Chan, said there’s been a lower vaccination rate among people with mental disorder.

She urged the government to work harder on getting these people vaccinated, saying their chance of suffering complications tend to be higher if they come down with Covid.