Israel is looking at a possible connection between Pfizer's vaccine and a number of heart inflammation cases, mostly in young men.
The condition is known as myocarditis.
Israel's health ministry says some of those cases, in men ages 16 to 30, happened after receiving the second dose of the Pfizer vaccine. It said in most cases, it was a mild illness that passed within a few days.
Pfizer says it has not seen a higher rate of the condition than would be expected in the general population and noted no causal link has been established.