U.S. chief medical adviser Dr. Antony Fauci has said that the United States will be looking at Israeli data on COVID-19 vaccine booster shots to clarify the level of risk involved in administering them to citizens under the age of 65.

“The real question that we have not yet answered is the safety data of an mRNA vaccine in young people vis-a-vis myocarditis,” said Fauci in a telephone interview with Reuters on Friday. Myocarditis, an inflammation of the heart muscles, is found in a small number of those who were vaccinated.

The data collected by the Israel Defense Forces on military recruits, specifically, is expected to shed light on the safety of the vaccines in the younger cohort with regard to Myocarditis, said Fauci.