Ms. Suwanda, who has no symptoms consistent with the coronavirus, said she decided against getting tested because she wanted to get out of quarantine as soon as possible.

“They said if you get tested and your results aren’t back by the end of the 14 days you will not be allowed to leave,” Ms. Suwanda said. “And they said we don’t know how long this is going to take.”

At quarantine facilities in California and Georgia, people are concerned that the lack of cleanliness and enforcement of protocols like social distancing is only increasing their chances of catching the virus. There are no gloves for passengers, there are no hand-sanitizing stations and each passenger has only one face mask that he or she must reuse for stretches of several days. Some people had no soap in their rooms.

People leaned on surfaces and touched counters without cleaning their hands before and after, according to people at military bases in California and Georgia. At the quarantine facility in Georgia, passengers wore the same single-use face mask for nearly a week, said Mark Pace, who was quarantined there and is now home in Florida.

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Michele Smith, 57, an administrative assistant who is quarantined at the Marine Corps Air Station Miramar in San Diego, said she had overheard people saying they were going to choose not to be tested so that they could leave as soon as they can, unless they fall so ill that they need to go to the hospital.

“That’s scary,” said Mrs. Smith, who said she and her husband decided to be tested. But on the other hand, the conditions in quarantine are so poor, she said, that she doesn’t blame them: “You do start to feel like you’re in jail.”