The U.S. Centers for Disease Control and Prevention announced new COVID-19 guidance on Monday that halves the previously recommended isolation period after testing positive for the virus and does not advise testing before leaving quarantine. Though some research and evidence backs up the health officials' decision, several experts and officials have decried the loosened measures.

Dr. Eric Topol, the founder and director of the Scripps Research Translational Institute, said that it was "reckless to proceed like this."

"Using a rapid test or some type of test to validate that the person isn't infectious is vital," he said, adding that there's "no evidence, no data to support this."

The CDC shortened the recommended isolation period for those infected with COVID-19, but have no symptoms, from 10 to five days. The federal agency also shortened the amount of recommended isolation time for those who were in close contact with someone who was infected.

CDC officials cited growing evidence that people with COVID-19 are most infectious in the first few days they're infected with the virus. Louis Mansky, the director of the University of Minnesota's Institute for Molecular Virology, recognized the agency's reasoning behind the new guidance.

"When somebody gets infected, when are they most likely to transmit the virus to another person?" he said. "It's usually in the earlier course of the illness, which is typically a day or two before they actually develop symptoms and then a couple of days to three days after that."

Still, the loosened recommendations have left some wary, especially amid the Omicron variant's rapid spread.

"The looser COVID guidelines make me nervous. I'm more hesitant to participate in holiday activities because of the Omicron variant and the seemingly more lax protocols,'' said Dana Martin, a 38-year-old Philadelphia teacher and educational consultant.

CDC Adjusts COVID Guidance
Though some research and evidence backs up the CDC's decision to loosen COVID-19 isolation guidance, several experts and officials have decried the loosened measures. The Centers for Disease Control and Prevention headquarters are seen in Atlanta, Georgia on April 23, 2020.Tami Chappell/AFP via Getty Images

The CDC has been under pressure from the public and the private sector, including Delta Air Lines, to explore ways to shorten the isolation time and reduce the risk of severe staffing shortages amid the Omicron surge. Thousands of airline flights have been canceled over the past few days in a mess blamed on Omicron.

"Not all of those cases are going to be severe. In fact, many are going to be asymptomatic," CDC Director Dr. Rochelle Walensky said Monday. "We want to make sure there is a mechanism by which we can safely continue to keep society functioning while following the science."

Mansky said CDC probably didn't include exit testing in its guidelines for logistical reasons: There is a run on COVID-19 rapid tests amid the spike in cases and the busy holiday travel season. In many places, at-home tests are difficult or impossible to find.

The CDC is "driven by the science, but they also have to be cognizant of the fact of, you know, what are they going to tell the public that they'll do," Mansky said. "That would undermine CDC if they had guidance that everybody was ignoring."

Qamara Edwards, director of business and events for Sojourn Philly, which owns four restaurants in Philadelphia, said about 15 percent of its employees are out sick with COVID-19, and staffing is tight.

The CDC changes are "great for businesses, they do allow people to return to work sooner than they've expected," Edwards said, though she understands why workers might be resistant and worried about their safety.

In Los Angeles, King Holder, who runs the StretchLab Beverly fitness business, likewise said Omicron has caused "caused ample" to his company, and he welcomed the more relaxed guidelines.

"The possibility of five days compared to 10-14 days is huge for our business and allows us to stay afloat," he said.

Marshall Hatch, senior pastor of New Mount Pilgrim Church on Chicago's West Side, said he is bracing for some confusion in his congregation. The church has been a strong advocate for testing, vaccinations and booster shots.

Hatch said the CDC's latest guidance is confusing and "a little incongruous."

"Either we're in a surge that we need to take very seriously or are we winding down the pandemic and that's why we're shortening the isolation and quarantine times," he said Tuesday. "They might want to give us a little more information to go with."

Hatch said some members of the largely Black congregation, particularly senior citizens, are skeptical of information from the government.

The CDC move follows global efforts to adjust isolation rules, with policies differing from country to country.

England last week trimmed its self-isolation period for vaccinated people who have tested positive for COVID-19 to seven days in many cases, provided two negative lateral flow tests are taken a day apart.

The French government said Monday that it will soon relax its isolation rules, although by exactly how much isn't yet clear.

Health Minister Olivier Veran said the rule changes will be aimed at warding off "paralysis" of public and private services. By some estimates, France could be registering more than 250,000 new infections per day by January.

Italy, meanwhile, is considering doing away with a quarantine altogether for those who have had close contact with an infected person as long they have had a booster shot. Projections indicate as many as 2 million Italians could be put in quarantine over the next two weeks as the virus spreads.

The U.S. airline industry applauded the CDC move.

"The decision is the right one based upon science," said the lobbying group Airlines for America.

But the head of a flight attendants union criticized the change, saying it could lead businesses to pressure sick employees to come back before they are well.

If that happens, "we will make clear it is an unsafe work environment, which will cause a much greater disruption than any 'staffing shortages,'" warned Sara Nelson, president of the Association of Flight Attendants-CWA International.

The Associated Press contributed to this report.

COVID Testing Site
The U.S. Centers for Disease Control and Prevention announced new COVID-19 guidance on Monday that halves the previously recommended isolation period after testing positive for the virus and does not advise testing before leaving quarantine. A young girl receives a self-administered COVID-19 test kit at a screening center at the Martin Luther King, Jr. Medical Center Campus in South Los Angeles, California, on December 27, 2021.Robyn Beck/AFP via Getty Images