CDC: If You're Vaccinated, You Don't Need To Mask Outdoors (Unless You're In A Crowd)

The CDC says people who are fully vaccinated do not need to wear a mask when they're outdoors, unless they're in a crowd, such as attending a live performance, sporting event or parade. People are considered fully vaccinated two weeks after receiving the second dose of the Pfizer or Moderna vaccines, or two weeks after the single dose Johnson & Johnson shot.

"If you are vaccinated, things are much safer for you," CDC Director Rochelle Walensky said Tuesday at a White House briefing. "If you are fully vaccinated and want to attend a small outdoor gathering — with people who are vaccinated and unvaccinated — or dine at an outdoor restaurant with friends from multiple households, the science shows you can do so safely, unmasked."

As part of the new guidance, the agency spelled out settings in which it's OK for fully vaccinated people to be unmasked including:

Walking, running, hiking or biking outdoors alone or with members of your household

Attending a small outdoor gathering with fully vaccinated family and friends

Attending a small outdoor gathering with a mixture of fully vaccinated and unvaccinated people

Dining at an outdoor restaurant with friends from multiple households

"We continue to recommend masking in crowded outdoor settings and venues such as packed stadiums and concerts where there is decreased ability to maintain physical distance and where many unvaccinated people may also be present," Walensky said. "We will continue to recommend this until widespread vaccination is achieved."

The new guidance "shows just how powerful these vaccines are in our efforts to end this pandemic," Walensky said.

The agency says COVID-19 vaccines are effective at protecting against illness, but urges people to continue to take precautions since officials are still learning how well the vaccines work to curb the spread of the virus.

In public settings, it's hard to know if others around you have been vaccinated or if they're at increased risk for severe COVID-19, so the CDC continues to recommend that fully vaccinated people follow guidance to protect themselves and others, including wearing a mask, when indoors or an outdoor setting or venue where masks are required. For instance, a city or municipality may continue to require masking at farmer's market, a graduation ceremony or youth sports.

The agency continues to recommend that everyone — including vaccinated people — avoid medium or large-sized gatherings, given the vaccines are not 100% effective at preventing infection, and there are documented cases of "breakthrough infections."

In addition, the CDC says that if you've been around a person who is sick and develop any symptoms of COVID-19, you should get tested and stay home.

The agency lists a range of settings where masking is still recommended for people who are fully vaccinated.

Attending a crowded outdoor event such as a live performance, parade or sporting event

Visiting a barber or hair salon

Visiting an indoor shopping mall or museum

Riding public transport

Attending a small indoor gathering with a mixture of fully vaccinated and unvaccinated people

Going to an indoor movie theater

Attending a full capacity service at a house of worship

Given more than 50% of adults in the U.S. have now received at least one dose, many public health experts agree that it's time to start relaxing restrictions, including this new guidance to go unmasked in outdoor settings.

Throughout the pandemic, infectious disease experts have pointed to the lower risks of being outside. "Outdoors is safer than indoors with all the natural airflow, " says Dr. Judith Guzman-Cottrill of Oregon Health & Science University.

Linsey Marr, a researcher at Virginia Tech who studies airborne virus transmission and has studied mask efficacy, notes that the evidence has long indicated that the risk of transmission outdoors is much lower than indoors.

"Virus just cannot accumulate in the air outdoors," Marr says. "It's like putting a drop of dye into the ocean. If you happen to be right next to it, then maybe you'll get a whiff of it. But it's going to become diluted rapidly into the huge atmosphere."

One meta-analysis published in The Journal of Infectious Diseases suggested that the coronavirus was nearly 19 times more likely to be spread indoors compared with outdoors.

But as Marr notes, other research suggests that the risk of outdoor transmission is even lower.

For instance, data from Ireland's Health Protection Surveillance Centre, obtained by The Irish Times, looked at more than 232,000 COVID-19 cases in that country through March 2021; it found that just 1 in 1,000 cases could be traced to outdoor transmission.

Dr. Monica Gandhi, an infectious disease specialist at the University of California, San Francisco, notes that other countries with high vaccination rates don't have outdoor mask mandates.

"Israel released their outdoor mask mandates a week or so ago. The U.K. does not mask outdoors," Gandhi says.

And in recent days, the nation's chief infectious disease expert, Anthony Fauci, called the risk of spread in outdoor settings "minuscule."

"It's pretty common sense now that the outdoor risk is really quite low," Fauci told ABC News. [Copyright 2021 NPR]