The FDA is requiring COVID vaccine makers Pfizer and Moderna to update their warnings about the possible risk of myocarditis and pericarditis.

Regulators say updated booster shots won’t be approved for healthy people under age 65 unless drugmakers conduct new trials.

In a major policy shift, federal health officials anticipate the shots will be made available to adults 65 and older as well as children and younger adults who have one or more risk factors that make them more vulnerable to severe COVID-19.