People who are fully vaccinated against Cobvid-19 can gather indoors with other fully vaccinated people without having to wear a mask or to maintain social distance, the US Centers for Disease Control said Monday.

Fully vaccinated people can also visit indoors with a single household of unvaccinated people who are at low risk for severe illness without masks or physical distancing.

“For example, fully vaccinated grandparents can visit indoors with their unvaccinated healthy daughter and her healthy children without wearing masks or physical distancing, provided none of the unvaccinated family members are at risk of severe Covid-19,” the CDC said.

But people should continue to wear masks and keep at least six feet of distance in public even after they become vaccinated, the agency added.

“Currently authorized vaccines in the United States are highly effective at protecting vaccinated people against symptomatic and severe Covid-19. Additionally, a growing body of evidence suggests that fully vaccinated people are less likely to have asymptomatic infection and potentially less likely to transmit SARS-CoV-2 to others,” the CDC said in its interim guidance.

“How long vaccine protection lasts and how much vaccines protect against emerging SARS-CoV-2 variants are still under investigation. Until more is known and vaccination coverage increases, some prevention measures will continue to be necessary for all people, regardless of vaccination status.”

In Massachusetts, there are 703,676 people who the Department of Public Health considers to be “fully vaccinated,” but the new guidance announced Monday by the CDC does not apply to all of them. The state considers someone to be “fully vaccinated if they have received the number of doses required to complete the vaccine series,” so two doses of either the Moderna or Pfizer vaccines and one dose of the Johnson & Johnson vaccine.

But the CDC does not consider someone to be fully vaccinated against the coronavirus until two weeks after their final dose (or single dose in the case of Johnson & Johnson) is administered. There were 389,087 people who had received two doses of a vaccine as of two weeks ago, meaning they all now fit the CDC’s definition of being fully vaccinated.