The race to curb the spread of the new coronavirus could be thwarted by Americans fearful of big medical bills if they get tested, low-income workers who lose pay if they take time off when sick, and similar dilemmas that leave the United States more vulnerable to the epidemic than countries with universal health coverage and sturdier safety nets.

As the test for the virus becomes more widely available, health-care experts predict that some people with flu-like illnesses — or those who may have been exposed — will avoid finding out whether they have been infected because they are uninsured or have health plans that saddle them with much of the cost of their care.

Making sure the right people get tested — and keeping them away from others if they are infected — is crucial to help diminish the virus’s spread within communities as it pops up in a growing number of states.

Now that federal health officials have ironed out initial problems with the test itself and enabled more labs to take part in the hunt for infection, this work of testing and quarantining is the essential second stage. Yet the government has not yet begun to tell Americans where to go for testing, and neither public nor private insurers are changing their rules to buffer people from testing-related charges.

Some preparations recommended by the Centers for Disease Control and Prevention are incompatible with the way benefits work. Officials have urged people to keep an adequate supply of their routine medicines in case they end up quarantined. But insurance companies seldom permit refills until a patient is nearly out of pills. The agency also urges people with respiratory illnesses to stay home from work. But with no federal sick leave requirements, some experts predict the virus will spread more rapidly.

For an international, fast-spreading epidemic, the nation’s health-care system and many workers’ benefits are “certainly not optimally designed,” said Sabrina Corlette, a research professor at Georgetown University’s Center on Health Insurance Reforms.

Federal funds cover the cost of the coronavirus test itself when it is run in federal, state or local public health laboratories. But that changes as academic and commercial labs get involved. In neither case does the government buffer people from bills for visiting a doctor’s office, urgent care center or emergency room, though nearly half of the 160 million Americans with insurance through their jobs have health plans with high deductibles.

“Deductibles are designed to make people think twice about going to the doctor if they are feeling sick,” said Larry Levitt, executive vice president for health policy at the Kaiser Family Foundation, a health-research organization. “In a potential pandemic, the last thing you want people to do is thinking twice about going to the doctor.”

America’s Health Insurance Plans, the industry’s main trade group, has issued guidance called “Keeping Americans Safe from Coronavirus.” The statement says insurers are “carefully monitoring the system” and working with the CDC to share information.

But it does not urge insurance companies to eliminate out-of-pocket costs for the tests or for visits to doctors or clinics for respiratory illnesses, saying that health plans may want to determine “whether policy changes are needed to ensure that people get essential care.”

Thomas Inglesby, director of the Center for Health Security at the Johns Hopkins Bloomberg School of Public Health, said eliminating the financial disincentive to get tested “needs to be at the top of the list” of problems that federal health officials tackle.

Inglesby said that other countries, including Western democracies with government-financed health-care systems, have not been fully publicizing their testing strategies. But he said, “Countries where patients could get large bills for diagnostic testing will have additional challenges identifying people.”

Even before the test was widely available in the United States, a few instances of people ending up with large, coronavirus-related medical bills have lit up Twitter.

In one case, a 29-year-old Miami engineer, Osmel Martinez Azcue, had been in China for work, returned home briefly, then flew to Italy for another quick assignment. By the time he arrived home on Jan. 27, he said in an interview, he had spent a miserable, feverish night in the Lisbon airport, popping ibuprofen as he waited for a connecting flight.

His mother, who lives in his apartment building, started researching the coronavirus and convinced him that he needed a test.

He thought it was probably the flu, but the next morning, he called an urgent care center, which told him that only two hospitals in town could help him.

He went immediately to Miami’s public hospital, Jackson Memorial, where emergency room workers, already alerted, said they rushed him into a quarantine room. A nurse in protective gear quizzed him about his travels, and a doctor told him he needed a CT scan, Azcue said.

He knew the inexpensive insurance he had switched to in the fall requires him to pay $5,000 upfront, so he asked the doctor to first give him a routine flu test, and, if it was positive for influenza, to send him home.

Less than two hours after he arrived, he left the hospital with a flu diagnosis and a Tamiflu prescription.

On Valentine’s Day, a bill arrived from National General Insurance that upset Azcue so much that he did not take his longtime girlfriend out to celebrate. It said he owed $3,270.75 unless he sent the insurer three months of records to prove that the flu had not been a preexisting medical condition. After his story appeared in the Miami Herald, the insurer withdrew the records demands late last week, saying he would owe $1,400.

Said Hopkins’s Inglesby: “It is in the public interest for us to have free testing available for people — not just the test itself but the process of getting tested.”

So far, doctors are not getting a lot of calls from worried patients, said Robert McLean, president of the American College of Physicians — the professional association of internists — and medical director of a 400-doctor medical group in southern Connecticut affiliated with the Yale New Haven Health System.

The health system has designed protocols so that “if someone is sick with a cough, everyone gets asked whether they have been to China” or other outbreak sites. “If there is any of that stuff, it gets triaged to a doctor for a phone call.”

But Scott Becker, chief executive of the Association of Public Health Laboratories, said he was thinking about the health system’s capacity the other night, when his wife wasn’t feeling well after work with what turned out to be the flu. They went to an urgent care clinic in suburban Maryland that was crowded.

“I’m thinking, this place is busy, and it’s a one-and-a-half-hour wait now. And we don’t have community spread here. What’s going to happen? We are going to quickly overwhelm clinics,” he said.

Meanwhile, Georgetown’s Corlette said work-related worries may also deter people from taking time off to get a test or staying home if they are sick. She noted that nearly one-third of all workers — and more than two-thirds of all low-income workers — do not get paid sick days.

“Workers who serve our food, take care of our elderly, take care of our kids, change our sheets — that’s a thing that should be keeping people up at night,” she said.