(CNN)Top US government officials are considering requiring everyone who enters the country to be tested for Covid-19 the day before their flight and having all travelers -- including US citizens and permanent residents -- be tested again after returning home, regardless of vaccination status, sources familiar with the discussions have told CNN.
Officials were deliberating the potential changes Tuesday night and no final decisions have been made, but the US Centers for Disease Control and Prevention confirmed in a statement that the agency is working to revise testing requirements for travelers because of the new Omicron variant.
"A revised order would shorten the timeline for required testing for all international air travelers to one day before departure to the United States," a CDC spokesman said in a statement. "This strengthens already robust protocols in place for international travel, including requirements for foreign travelers to be fully vaccinated."
Currently, vaccinated travelers are required to test three days before their departures. The move under consideration would shorten that timeline to one day.
A mandatory quarantine for US citizens returning home is not under consideration, according to a White House official.
"The administration continues to evaluate the appropriate measures to protect the American people from COVID-19, especially as we learn more about the Omicron variant, including considering more stringent testing requirements for international travel. Policy discussions are ongoing across the government and no final decisions have been made," a White House official told CNN.
CDC Director Dr. Rochelle Walensky told reporters earlier Tuesday that the agency was "evaluating how to make international travel as safe as possible, including pre-departure testing closer to the time of flight and considerations around additional post-arrival testing and self-quarantines."
Walensky also said the CDC is expanding surveillance at four major international airports to monitor for the Omicron variant among travelers. The CDC plans to provide the names of passengers on flights entering the US from southern Africa to state and local public health departments, a health official confirms. This is in line with a CDC order that airlines must collect contact information from passengers before their arrival, so they can then identify and locate passengers who may have been exposed to a person with Covid-19 for follow-up. Airlines were ordered to start complying with this only weeks ago. It's unclear how many flights this specific instance will apply to.
Dr. Vivek Murthy, the US surgeon general, said on CNN's "Erin Burnett OutFront" on Tuesday night that "the CDC is considering a number of measures right now. It hasn't fully decided on what it's implementing, but I do believe some of the measures its considering will have a substantial impact on our ability to detect virus before it arrives here."
On Monday, the US banned all travel from South Africa and seven neighboring nations, with the exception of US citizens and legal permanent residents, who must test negative to enter the US but not once they have arrived.
Asked Tuesday how long current travel restrictions would remain in place, President Joe Biden said, "Well, it kind of depends."
"It's going week-to-week, to determine what we need and what the state of affairs (is). We're going to learn a lot more in the next couple of weeks about the lethality of this virus, about how much it spreads, about whether what we have can control it, etc.," he continued.
Biden on Thursday is slated to unveil a federal strategy to address Covid-19 this winter. The President has said the new strategy will be focused "not with shutdowns or lockdowns, but with more widespread vaccinations, boosters, testing and more."
The Biden administration has indicated so far that further restrictions on travel are not anticipated.
Research on the new variant -- including on its severity, transmissibilty and detectability -- is rapidly evolving.
On Monday, Biden's chief medical adviser, Dr. Anthony Fauci, said on CNN's "The Lead" that while PCR Covid-19 detection tests and some rapid antigen tests could detect the new variant, it wasn't clear whether all rapid tests could detect it. But Jeff Zients, the White House's Covid-19 response coordinator, confirmed Tuesday that the FDA believes "the high-volume PCR and rapid antigen tests widely used in the US will be effective in detecting the variant."
There are anecdotal reports suggesting that most cases of the Omicron variant Covid-19 have been mild so far. But scientists say it will take weeks to know how dangerous the new variant is.
The Omicron variant hasn't yet been detected in the United States. However, public health and government officials have repeatedly emphasized that the current travel restrictions on countries in southern Africa won't necessarily prevent the variant's arrival to the US. Rather, they will give the country some lead time to prepare for it.
"(T)ravel restrictions can slow the speed of Omicron, it cannot prevent it," the President said on Monday. "But here's what it does: It gives us time. It gives us time to take more actions, to move quicker, to make sure people understand you have to get your vaccine."
This story has been updated with additional details Tuesday.