The State Department announced on Thursday that Americans should not travel outside the country, and that citizens abroad should either return home or stay in place as the corona virus pandemic grows.
Some Americans overseas have urged the Trump administration to evacuate them.
The department raised its global health advisory to Level 4, or “do not travel,” which is the highest warning, usually reserved for nations that are war zones or facing serious disruptions such as political unrest or natural disasters.
The announcement is a recommendation, not a requirement. Millions of Americans are still overseas, and many are likely to opt to remain in place.
Some tourists or American citizens without long-term living arrangements or support networks abroad have been trying to get back to the United States, but have found that difficult because of border closings or flight cancellations and other transportation shutdowns. For example, American students trapped in Peru because of new travel restrictions imposed by the government there have been pleading with American officials to get them back to the United States.
With little evidence, Trump pushes idea that an old malaria drug could be a cure.
President Trump on Thursday exaggerated the potential of drugs available to treat the new corona virus, including an experimental antiviral treatment and decades-old malaria remedies that hint of promise but so far show limited evidence of healing the sick.
No drug has been approved to treat the new corona virus, and doctors around the world have been desperately administering an array of medicines in search of something to help patients, especially those who are severely ill.
The malaria drugs, chloroquine and hydroxychloroquine, are among the remedies that have been tried in several countries as the virus has spread around the world, killing at least 9,800.
Doctors in China, South Korea and France have reported that the treatments seem to help. But those efforts have not involved the kind of large, carefully controlled studies that would provide the global medical community proof that these drugs work on a significant scale.
In a White House briefing Thursday, Mr. Trump said the anti-malaria drugs had shown “tremendous promise.”
The drugs’ potential has been highlighted during broadcasts on one of Mr. Trump’s favorite news channels, Fox News, where hosts like Laura Ingraham, Tucker Carlson and Jeanine Pirro have trumpeted the possibility of a real treatment.
But the F.D.A. has not approved any drugs for use in the treatment of corona virus.
At a briefing on Thursday, Dr. Stephen M. Hahn, who has been the commissioner of the Food and Drug Administration for only three months, tended to walk back some of the president’s more inflated predictions that these drugs might vanquish the virus altogether.
He said Mr. Trump had asked the agency to look into chloroquine to fight the corona virus, and that it was setting up a large clinical trial to evaluate the drug.