“Vaccinated persons with an exposure to someone with suspected or confirmed COVID-19 are not required to quarantine if they meet all of the following criteria,” the CDC added.

The criteria: They must be fully vaccinated — having had both shots with at least two weeks having passed since the second shot. That’s because it takes two weeks to build full immunity after the second dose of vaccine.

But the CDC says protection may wear off after three months, so people who had their last shot three months ago or more should still quarantine if they are exposed. They also should quarantine if they show symptoms, the CDC said.