They should still wear masks but no quarantines are necessary, the agency said in new guidance that cited growing data about the effectiveness of the shots.
Americans who are fully vaccinated against Covid-19 can safely travel at home and abroad, as long as they take basic precautions like wearing masks, federal health officials announced on Friday, a long-awaited change from the dire government warnings that have kept many millions home for the past year.
In announcing the change at a White House news conference, officials from the Centers for Disease Control and Prevention stressed that they preferred that people avoid travel. But they said growing evidence of the real-world effectiveness of the vaccines — which have been given to more than 100 million Americans — suggested that inoculated people could do so “at low risk to themselves.”
The shift in the C.D.C.’s official stance comes at a moment of both hope and peril in the pandemic. The pace of vaccinations has been rapidly accelerating across the country, and the number of deaths has been declining.
Yet cases are increasing significantly in many states as new variants of the coronavirus spread through the country. Just last Monday, Dr. Rochelle P. Walensky, the C.D.C. director, warned of a potential fourth wave if states and cities continued to loosen public health restrictions, telling reporters that she had feelings of “impending doom.”
Some public health experts were surprised by Friday’s announcement and expressed concern that government was sending confusing signals to the public.
“It’s a mix of ‘please don’t travel,’ at the same time this is easing travel for a subset of people,” said Dr. Wafaa El-Sadr, professor of epidemiology and medicine at Columbia Mailman School of Public Health. “I think it’s very confusing and goes counter to the message we heard earlier this week, to ‘stay put,’ ‘hold on,’ ‘be patient.’ And that worries me. Public health messaging has to be very clear, very consistent, and it has to be very simple.”
Dr. Walensky herself seemed to acknowledge the apparent mixed messaging during Friday’s news conference. “The science shows us that getting fully vaccinated allows you to do more things safely, and it’s important for us to provide that guidance even in the context of rising cases,” she said.
The travel industry welcomed the new guidance, hoping it might be the beginning of a turn of fortune for airlines, hotels and tourist destinations, which have suffered mounting losses for more than a year.
“As travel comes back, U.S. jobs come back,” said Roger Dow, the chief executive of the U.S. Travel Association, an industry group, said in a statement.
Federal officials remained adamant that people who have not been fully vaccinated should not travel at all, a position widely supported by public health experts.
“If you are fully vaccinated, you can return to travel, but if you are not, there is still a lot of virus circulating and it is still a risky undertaking and you should defer until you get vaccinated or the situation improves,” said Caitlin Rivers, an epidemiologist and assistant professor at the Johns Hopkins Bloomberg School of Public Health.
If unvaccinated people must travel, the C.D.C. recommends they be tested for coronavirus infection one to three days before their trip and again three to five days after it’s over. They should self-quarantine for seven days after a trip if they get tested and for 10 days if they do not get tested, the agency said.
People are considered fully vaccinated two weeks after receiving the single dose of the Johnson & Johnson vaccine, or two weeks after receiving the second dose of either the Pfizer-BioNTech or Moderna shot. Some 58 million people in the U.S., 22 percent of the adult population, have been fully vaccinated, according to the latest numbers from the C.D.C.
Scientists are still not certain whether vaccinated people may become infected, even briefly, and transmit the virus to others. A recent C.D.C. study suggested such cases might be rare, but until that question is resolved, many public health officials feel it is unwise to tell vaccinated Americans simply to do as they please. They say it is important for all vaccinated people to continue to wear masks, practice social distancing and take other precautions.
Under the new C.D.C. guidance, fully vaccinated Americans who are traveling domestically do not need to be tested for the coronavirus or follow quarantine procedures at the destination or after returning home. When they travel abroad, they only need to get a coronavirus test or quarantine if the country they are going to requires it.
However, the guidance says they must have a negative coronavirus test before boarding a flight back to the United States, and they should get tested again three to five days after their return.
The recommendation is predicated on the idea that vaccinated people may still become infected with the virus. The C.D.C. also cited a lack of vaccine coverage in other countries, and concern about the potential introduction and spread of new variants of the virus that are more prevalent overseas.
Most states have accelerated their timelines for opening vaccinations to all adults, as the pace of vaccinations across the country has been increasing. As of Friday, an average of nearly three million shots a day were being administered, according to data reported by the C.D.C.
The new advice adds to C.D.C. recommendations issued in early March saying that fully vaccinated people may gather in small groups in private settings without masks or social distancing, and may visit with unvaccinated individuals from a single household as long as they are at low risk for developing severe disease if infected with the virus.
Travel has already been increasing nationwide, as the weather warms and Americans grow fatigued with pandemic restrictions. Last Sunday was the busiest day at domestic airports since the pandemic began. According to the Transportation Security Administration, nearly 1.6 million people passed through the security checkpoints at American airports.
But the industry’s concerns are far from over. The pandemic has also shown businesses large and small that their employees can often be just as productive working remotely as in face-to-face meetings. As a result, the airline and hotel industries expect it will be years before lucrative corporate travel recovers to prepandemic levels, leaving a gaping hole in revenues.
And while leisure travel within the United States may be recovering steadily, airlines expect it will still take until 2023 or 2024 for passenger volumes to reach 2019 levels, according to Airlines for America, an industry group. The industry lost more than $ 35 billion last year and continues to lose tens of millions of dollars each day, the group said.
Many countries, including those in the European Union, still block most Americans from coming. Some are starting to make exceptions for those who are vaccinated. As of March 26, fully vaccinated Americans who can present proof of vaccination can visit Iceland, for example, and avoid such restrictions as testing and quarantine, the country’s government said
The C.D.C. on Thursday also issued more detailed technical instructions for cruise lines, requiring them to take steps to develop vaccination strategies and make plans for routine testing of crew members and daily reporting of Covid-19 cases before they can run simulated trial runs of voyages with volunteers, before taking on real passengers. The C.D.C.’s directives acknowledge that taking cruises “will always pose some risk of Covid-19 transmission.”
Some destinations and cruise lines have already started requiring that travelers be fully vaccinated. The cruise line Royal Caribbean is requiring passengers and crew members 18 or older to be vaccinated in order to board its ships, as are Virgin Voyages, Crystal Cruises and others.
For the moment, airlines are not requiring vaccinations for travel. But the idea has been much talked about in the industry.
Niraj Chokshi contributed reporting.
