There's a probable link between young men who received the second dose of Pfizer's COVID-19 vaccine and a heart inflammation condition.

That's what Israeli health officials said Tuesday (June 2) they'd observed from December to May.

Pfizer has said it has not observed a higher rate of the condition, known as myocarditis, than it would normally be expected in the general population.

In Israel, 275 cases of myocarditis were reported between December 2020 and May 2021 among more than 5 million vaccinated people, according to a study commissioned by the health ministry.

Most patients who experienced heart inflammation spent no more than four days in hospital, and 95% of the cases were also classified as "mild."

The study found the link between myocarditis and a Pfizer second dose was observed more among men aged 16-19 than in other age groups.

Israel has now held off vaccinating its 12-15 year-old population.

Pfizer said in a statement that it is aware of the Israeli observations of myocarditis, but it noted that no causal link to its vaccine has been established.

Israel has been a world leader in its vaccination rollout.

About 55% of its population has already been vaccinated.