Sweden will pause the use of Moderna's Covid-19 vaccine for people born in 1991 and later after reports of possible rare side effects, such as myocarditis, the Swedish health agency has said, according to Reuters.

The health agency said data pointed to an increase in myocarditis and pericarditis cases among youths and young adults who had been vaccinated.

"The connection is especially clear when it comes to Moderna's vaccine Spikevax, especially after the second dose," it said in a statement, adding that the risk of being affected was very small.

The health agency said it now recommended the Comirnaty vaccine from Pfizer/Biontech instead. People born in 1991 or later that had received a first Moderna shot, some 81,000 people, would not get a second Moderna jab, it added.