Worried by an outbreak of Ebola in Uganda, the Biden administration said today that travelers who had been to that country would be redirected to airports where they can be screened for the virus and warned physicians to be alert for potential cases in the United States.

No cases of Ebola have yet been reported outside Uganda, but the virus — which spreads only through contact with bodily fluids and is not airborne — is highly contagious. American officials are watching the Uganda outbreak closely because there are no approved vaccines or treatments for the type of Ebola virus causing the outbreak there.

The director of the Centers for Disease Control and Prevention ordered the airport screenings, and the State Department issued an alert saying the measures would apply to all passengers, including U.S. citizens.

Screenings were expected to begin today for some passengers, but the travel restrictions will not go into effect until next week, according to an official familiar with the plan, who stressed that both the restrictions and the alert to doctors were issued as precautions.

As of today, there were 44 confirmed cases and 10 deaths in Uganda, with a few dozen possible cases and 20 deaths still under investigation, making this the largest outbreak in that country in 20 years. At least six infections and four deaths occurred among health care workers.

Arriving passengers who have been in Uganda during the past 21 days will be funneled to one of five United States airports: Kennedy International Airport, in New York; Newark Liberty International Airport, in New Jersey; O’Hare International Airport, in Chicago; Hartsfield-Jackson Atlanta International Airport; and Dulles International Airport, in Washington, D.C.

An administration official said 62% of air passengers who have been to Uganda already go through those airports. Once in the United States, passengers will undergo temperature checks and fill out health questionnaires, which will be shared with local officials, before heading to their final destinations.

The CDC also urged doctors to obtain a travel history from patients whom they suspect of having Ebola.

“While there are no direct flights from Uganda to the United States, travelers from or passing through affected areas in Uganda can enter the United States on flights connecting from other countries,” the CDC alert said.

After the coronavirus pandemic and monkeypox outbreak, President Joe Biden and other federal officials are well aware that infectious disease outbreaks also carry political risks, which may account for the administration’s caution. But there is also precedent for travel restrictions.

In February 2020, after the coronavirus emerged in China, the Trump administration barred entry by most foreign nationals who had recently visited the country and put some American travelers under a quarantine as it declared a rare public health emergency.

And during an Ebola outbreak in West Africa in 2014, the Obama administration forced passengers to fly to U.S. airports with screening procedures in place. President Barack Obama himself became engaged in the Ebola response after cases emerged in the United States.

Ebola is a rare and deadly disease, seen mostly in sub-Saharan Africa. The infection begins with mild respiratory symptoms, but left untreated can rapidly damage internal organs.

Patients eventually bleed from their eyes, nose, mouth and rectum — dramatic symptoms that have stoked fear of the virus. Ebola kills about half of those infected on average, usually within two weeks of the appearance of symptoms.

The CDC and the World Health Organization both provide information on how to diagnose and treat patients infected with the virus.

The current outbreak was first detected in Mubende, Uganda, and has spread to four other districts within a 75-mile radius. There will be many more cases and deaths before the virus can be contained, said Dr. Fiona Braka, emergency operations manager at the WHO regional office for Africa, based in Brazzaville.

“We are concerned because we still haven’t reached the peak,” Braka said.

The virus was circulating undetected for some time, and even after the first patient was diagnosed, health officials have been able to trace only three-quarters of the people who may have been exposed, Braka said.

The remaining contacts have scattered, raising the possibility that cases will sprout in other parts of the country or the world.

Ebola is highly contagious, and previous outbreaks have quickly spiraled out of control. The largest tore through West Africa in 2014 and accounted for more cases than all previous ones combined. By its end, the WHO reported 28,616 cases and 11,310 deaths.

The toll included 11 Americans, nine of whom contracted the disease outside the United States. Two of them died.

The WHO has twice declared a public health emergency of international concern — the organization’s highest alert — for Ebola: in 2014, and again in 2019, when the virus surfaced in the Congo.

The vaccines and treatments approved for Ebola target what is known as the Zaire species, the primary source of previous outbreaks. But they are ineffective against the Sudan species now circulating in Uganda.

Anticipating that vaccines against the Sudan species might someday be necessary, scientists have been working on at least eight candidates.

The furthest along in development is a single-dose vaccine developed by the Vaccine Research Center at the National Institutes of Health, which has been licensed to the Sabin Vaccine Institute.

The vaccine has been shown to be safe, produces copious antibodies against the virus and is highly protective against the Sudan virus in monkeys. About 100 doses are readily available.

Another vaccine candidate, made by a British team, targets both the Zaire and Sudan species but is in early-stage trials. Only 81 doses are available.

Both candidates could be made available in clinical trials during the current outbreak, pending approval by Ugandan health authorities.

The Sabin Vaccine Institute also has enough bulk material to produce 40,000 doses of its vaccine, stored at a biotech company called ReiThera, in Italy. But filling and finishing those doses in vials will take at least until the end of the year, according to Dr. Rick Koup, acting director of the federal vaccine center.

Health officials came up against similar hurdles in acquiring doses of the monkeypox vaccine, which hindered the response in the initial weeks of the U.S. outbreak. That vaccine is still in short supply worldwide.

“These are two rapid-succession cases where clearly, we need to come up with a better solution,” Koup said.

Few facilities can fill and finish vaccines, creating a bottleneck when doses are urgently needed. On the other hand, finished doses expire more quickly, requiring emergency stocks to be constantly replenished.

Two months ago, Koup said, he would have predicted that finishing doses of a suddenly needed vaccine was “not going to be a big issue.” But in hindsight, he said, “obviously, we should have had a few thousand doses filled.”

Activists lauded federal scientists for having the foresight to develop vaccines for emerging pathogens. But instead of relying on private companies, the government should own and control a vaccine manufacturing facility that can be used during an outbreak, said James Krellenstein, a founder of PrEP4All, a group that promotes access to HIV care.

“How many outbreaks do we have to watch spiral out of control because of the lack of vaccine manufacturing capacity before the U.S. government fixes this problem?” Krellenstein said. “The thing that’s very frustrating is, this is really a fixable problem.”

Scientists have also been developing so-called monoclonal antibodies that can broadly neutralize multiple species of Ebola and reverse symptoms. One dose of an antibody cocktail has been shown to ease even severe symptoms in monkeys infected with the Zaire, Sudan and Bundibugyo species of Ebola. But the treatment is still in early-stage trials.

“If you go fishing for these rare rainbow unicorn antibodies, you can certainly find ones that are cross-neutralizing and cross-protective” against various types of Ebola, said Kartik Chandran, a virus expert at the Albert Einstein College of Medicine in New York who helped develop the treatment.

“We knew it was only a matter of time before we had another Ebola outbreak that wasn’t caused by Zaire,” he added.

In Uganda, officials have moved quickly to scale up the response to the unexpected outbreak. Contact tracing continues to increase, and about 950 village health officials in the affected districts have been trained to watch for symptoms. They have been given personal protective equipment, thermometers and beds, Braka said.

Learning from previous outbreaks, officials moved testing from the Uganda Virus Research Institute in Entebbe to a mobile lab in Mubende, the outbreak’s epicenter, she added. Confirmation of the diagnosis now takes just six hours.

This article originally appeared in The New York Times.

© 2022 The New York Times Company