An interview with a passenger at Chicago’s O’Hare airport. (Melissa Maraj/U.S. Customs and Border Protection via AP)

All travelers flying to the United States from the three countries hit hardest by the Ebola outbreak in West Africa will now have to travel through the five airports with enhanced screening, officials announced Tuesday.

This new rule, which goes into effect Wednesday, closes what had been a relatively small gap in the stricter screening measures rolled out this month. The enhanced measures, which included temperature checks and Ebola-specific questionnaires, was put into place at five U.S. airports to screen people who had been in Liberia, Sierra Leone or Guinea.

There are no direct flights to the United States from the three countries. About 150 people typically fly to the United States from these places each day, the Centers for Disease Control and Prevention says, often arriving after transferring planes at European hubs such as Brussels or London. And federal officials say 94 percent of these travelers fly into one of five U.S. airports: John F. Kennedy International Airport in New York; Washington Dulles International Airport outside Washington, D.C.; O’Hare International Airport in Chicago; Hartsfield-Jackson International Airport in Atlanta; and Newark Liberty International Airport near New York.

But this meant that 6 percent of travelers — or roughly nine people a day, according to the CDC’s numbers — would have avoided the measures meant to catch potential Ebola cases before they leave the airport.

“We are continually evaluating whether additional restrictions or added screening and precautionary measures are necessary to protect the American people and will act accordingly,” Jeh Johnson, secretary of Homeland Security, said in a statement Tuesday.

Meanwhile, the number of people traveling to the United States from these countries has plummeted recently. The number of people flying in to New York’s JFK airport from one of these three countries has dropped in half, to about 80 arrivals a day, officials said.

Of course, there are limits to what this screening can accomplish. A person can unknowingly contract Ebola and exhibit no symptoms while traveling, which means the screening would be unable to identify them as a possible carrier of the illness.

Ashley Halsey contributed to this report.