Still, she added, “I don’t lose sleep over this.”

Michael Nunn, 66, a retired social worker in Traverse City, Mich., said the news of Ms. Vinson’s travels had prompted him to avoid planes for a while. He plans to drive the more than 2,000 miles to Los Angeles for Christmas instead of flying.

And in New York, where a possible case — later determined not to be Ebola — at Yale University in Connecticut added some unease to the day, a package-delivery messenger named David Evans said that on a worry scale of 1 to 10, “I’m about an eight and a half right now.” He said that he handled packages from unknown locations, and that he had no way to know who had touched them or where their contents originated.

As the revelations about Ms. Vinson’s travels raised anxieties, at least six schools in Texas and Ohio said they were shutting their doors because students or staff members had been on Ms. Vinson’s flight, or had flown on the same plane after she had. In Akron, Ohio, the Resnik Community Learning Center was closed for cleaning until Monday because a student’s parent had spent time with Ms. Vinson, school officials said.

“This is panic,” said Dr. Paul A. Offit, chief of the infectious diseases division and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia. “This reminds me of the early days of AIDS, when people were afraid to walk into a grocery store and pick up a piece of fruit because they didn’t know who’d touched it. This doesn’t follow the epidemiology of the disease. This isn’t flu or smallpox. It’s not spread by droplet transmission. As long as nobody kissed the person on the plane, they’re safe.”

Thomas W. Skinner, a spokesman for the C.D.C., said that there was no known medical reason for closings, and that the agency had not advised any school to shut its doors.

Nevertheless, officials who closed facilities or asked workers to stay off the job said they were trying to calm public fears, not inflame them. In statement after statement, they said Thursday that they were acting “out of an abundance of caution.”