Second vaccine doses raise the risk of myocarditis in young men, but the condition remains very rare.

Here’s what you need to know: ImageNorthwell Health workers protested a state vaccine mandate outside of Staten Island University Hospital in August.Credit…Yana Paskova for The New York Times Northwell Health, New York State’s largest health care provider, announced on Monday that it had fired 1,400 of its employees who refused to get vaccinated against the…