Israel health officials have found a probable link between Pfizer Inc. and BioNTech SE's coronavirus vaccine and dozens of cases of heart inflammation in young men following the second dose of the vaccine, the Health Ministry said late Tuesday.

The vaccine has been administered to more than 5 million people in the country, and the number of coronavirus cases has plummeted. The Health Ministry said on Wednesday that despite the possible link, it would expand its vaccination drive to 12–16-year-olds. The U.S. Food and Drug Administration has authorized its use for this age group.

According to a study by health officials, there were 275 cases of myocarditis identified between December 2020, when the vaccination drive began, and May 2021, including 148 cases within a month after vaccination. Of these, 27 cases occurred after the first dose and 121 following the second dose. In both cases, about half were in people with previous medical conditions.

At this time, there's still no indication that the cases are due to the vaccine, Pfizer said in a statement. Myocarditis is often caused by viral infections, and Covid infections have been reported to cause the condition, the U.S. drugmaker said. BioNTech said more than 300 million doses of the COVID-19 vaccine have been administered globally and the "benefit risk profile" of the vaccine remains positive.

"A careful assessment of the reports is ongoing and it has not been concluded," the company said. "Adverse events, including myocarditis and pericarditis, are being regularly and thoroughly reviewed by the companies as well as by regulatory authorities."

Most of the cases occurred in young men, especially those between 16 and 19 years old. In most cases, patients were hospitalized for four days or less, and in 95% of the cases were classified as mild, the ministry said.

"The risks from contracting coronavirus are higher than the risks from getting the vaccine," the Health Ministry said. The number of those who contracted myocarditis was small, and in most cases, patients recovered with no complications, it said.

Israel said in late April that it was looking into the cases to see if there's a connection with the vaccine.