Vaccinated people can ditch masks and distancing, the CDC says. Experts think the guidance is overdue but may be too broad.

• Fully vaccinated Americans no longer have to mask up or distance at indoor or outdoor gatherings.
• The new CDC rule is overdue, experts said, but there are still circumstances that warrant caution.
• If you live in a hotspot or have unvaccinated kids, you may not want to ditch your mask yet.

For the first time in more than a year, Americans have a green light to participate in any kind of activity - large or small, indoor or outdoor - without wearing a mask or physically distancing, as long as they're fully vaccinated.

That's according to new Centers for Disease Control and Prevention guidelines unveiled on Thursday.

"If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic," CDC Director Rochelle Walensky said at a White House briefing. "We have all longed for this moment when we can get back to some sense of normalcy."

Walensky cited a few reasons for the relaxed restrictions: Daily cases are trending down and vaccines have been shown to be highly effective at preventing COVID-19, even in the face of new variants. The shots even seem to reduce transmission.

For that reason, the CDC's announcement is "long overdue," Leana Wen, the former health commissioner of Baltimore, told Insider.

"That's exactly what I've been calling for," Wen said. "Once people are fully vaccinated, they are not a threat to public health and they should be able to resume all aspects of pre-pandemic normal if they so choose."

But several public-health experts told Insider that there are still caveats to bear in mind. For one thing, many vaccinated Americans live with others who haven't been vaccinated yet - including young kids.

Plus, the new CDC guidelines rely on an honor system, so there's little way to verify that the maskless people around you have gotten their shots.

"Unless you go to an event where everyone is truly mandated to provide proof of vaccination, when you have young kids, whether it's indoors or outdoors, you're going to always have that degree of hesitation," Dr. Vivek Cherian, an internal-medicine physician in Baltimore, told Insider. "I feel like parents are still going to be - and should be - more cautious, especially when you're talking about indoor events."

The rules aren't a free-for-all

The new CDC guidelines underscore "how confident we are in these vaccines and the ability for these vaccines really protect people," Anne Rimoin, an epidemiology professor at the University of California, Los Angeles, told Insider.

Because of that, several experts said, people who are immunized probably don't need to worry about whether others are telling the truth about their vaccination status.

"Say you have 1,000 people at an event and all of them say they're vaccinated - but the truth is, maybe 50 people are unvaccinated," Cherian said. "The people who are unvaccinated really only pose a threat to those other 50 individuals."

Still, even with the new rules, Americans will need to evaluate their own risk tolerance.

"It doesn't mean that you have to take your mask off," Rimoin said. "It means that you can take your mask off."

She added: "If you are still feeling vulnerable, if you're somebody who has a compromised immune system, if you are in an area when you're still higher transmission, then the conservative thing to do would be to continue to wear a mask in situations where you're going to be around people where you don't know what their vaccination status is."

Though daily coronavirus cases in the US have declined 33% in the last two months, there are still pockets of the country - including rural parts of Colorado and New Mexico - where transmission is high. So Emily Gurley, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, said people should factor in COVID-19 case rates in their local area.

"You've got to know what's happening in your neighborhood, in your community," Gurley said. "If for whatever reason, there are a bunch of kids in your neighborhood who have it, well then maybe you're a bit more cautious."

Experts also predict that many private companies will maintain mask requirements.

"We don't walk around with our vaccinated status on our foreheads," Gurley said. "So I think a lot of places - airplanes and airports, places where people are congregating - will keep some of those measures."

The CDC's message could encourage people to get vaccinated

Wen said it may have been more prudent for the CDC to suggest, for now, that fully vaccinated people just hang out with each another in whatever setting they choose.

"We're missing a critical step, and that step is fully vaccinated people around other fully vaccinated people in large or small groups," Wen said. "That should be safe, but now we're going from 'you can only dine indoors with a few people' to 'everybody can take off their masks because we're not checking their vaccination status.'"

She added: "I would feel a lot more comfortable at a concert of 10,000 people who are all fully vaccinated than a conference room of 20 people, 19 of whom are not vaccinated."

However, there are benefits to a strong, simple message from the CDC.

"The CDC is at risk for being irrelevant and their advice not trusted," Wen said. "They need to clearly demonstrate the power of the vaccine in preventing infection and illness."

At the start of the pandemic, the CDC was criticized for inconsistent messaging on masks. More recently, some public-health experts have argued that the agency has been too conservative in its guidelines for vaccinated folks.

Thursday's announcement could shift that public perception.

"It can have an added benefit of encouraging people to get vaccinated, as opposed to having this kind of convoluted message that you can get vaccinated, but you're still not really in the clear," Cherian said. "That doesn't make sense to a lot of people, nor should it. The CDC updating their guidance certainly adds credibility."

Of course, it's still possible that the agency may need to reinstate mask rules if new variants challenge the effectiveness of vaccines. But experts are optimistic.

"You're talking about getting back to our pre-COVID life," Cherian said. "This is going to take a big step in that direction."