Federal health officials on Wednesday effectively shortened quarantine periods for those who may have been exposed to the coronavirus, hoping to improve compliance among Americans and reduce the economic and psychological toll of long periods of seclusion.
Citing the spiraling number of infections nationwide, officials at the Centers for Disease Control and Prevention also urged Americans again to avoid travel over the holiday season.
“The C.D.C. recommends the best way to protect yourself and others is to postpone travel and stay home,” Dr. Henry Walke, who oversees day-to-day management of pandemic response at the agency, said at a news briefing.
People who choose to travel over the holiday season despite the warnings should consider getting tested for coronavirus infection one to three days before their trip, and again three to five days after return, Dr. Walke and other officials said.
It is the first time the agency has urged testing for domestic travelers; until now, testing was recommended only for Americans traveling internationally. Dr. Walke noted that testing before and after travel “does not eliminate all risk.”
Travelers returning home should keep nonessential activities to a minimum for at least seven days if they are getting tested, and for 10 days if they are not getting tested. (Many states already require travelers to self-quarantine after arrival, though the rules vary from state to state.)
Federal health officials also offered two new ways to shorten quarantine periods. Those without symptoms may end quarantine after seven days if they are tested for the virus and receive a negative result, or after 10 days without a negative test.
P.C.R. or rapid tests are both acceptable, the officials said, and should be taken within 48 hours of the end of the quarantine period. People should continue to watch for symptoms for 14 days.
(Quarantine refers to people who are well but may become ill; isolation refers to those known to be ill.)
Until now, the C.D.C. has recommended a 14-day quarantine period following potential exposure, and Dr. Walke stressed that the full two weeks is still considered ideal and the surest way to curb transmissions.
While a shortened quarantine period may be more palatable to Americans, officials acknowledged that the new guidance might lead to some infections being missed.
“We can safely reduce the length of quarantine, but accepting that there is a small residual risk that a person who is leaving quarantine early could transmit to someone else if they became infected,” said Dr. John Brooks, the chief medical officer for the Covid-19 response at the C.D.C.
Some patients may not develop symptoms until two weeks after exposure, and even longer in a very small fraction of cases. Infected individuals may pass the virus to others before they develop symptoms; recent studies show they are most infectious two days before symptoms begin, and for about five days afterward.
The new recommendations do not have the force of law. Federal officials share them with state and county public health agencies, who make their own determinations based on local conditions and needs.
The agency’s warnings against holiday travel echoed those issued just a week before Thanksgiving. Millions of Americans hit the road nonetheless to spend the holiday with friends and family, though the number of travelers was lower than in a typical year.
“Cases are rising, hospitalizations are increasing, deaths are increasing,” Dr. Walke said. “We need to try to bend the curve, stop this exponential increase.”
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Dr. Cindy Friedman, chief of the travelers health branch at the C.D.C., said the agency was reiterating the message further in advance of the Christmas holiday to provide more time for people to plan ahead, “think about the safest option for them and their families” and make “tough choices.”
“We know it’s a hard decision, and people need time to prepare and have discussions with family and friends and to make these decisions,” Dr. Friedman added. Even a small percentage of infected travelers could “translate into hundreds of thousands of additional infections.”
Hospitals are already overwhelmed in many regions, as cases have been rising rapidly, with the country adding over a million new infections during a recent one-week period, according to data maintained by The New York Times.
Daily deaths have been exceeding 2,000 for the first time since early May, and close to 100,000 Americans are already hospitalized.
“We are at the point now, even before Christmas, that there may not be room at your hospital, because we don’t have enough health care workers to take care of you,” said Michael Osterholm, a member of President-elect Joseph R. Biden Jr.’s Covid-19 advisory board, who also urged Americans to stay home.