As government officials race to limit the spread of the new coronavirus, fundamental elements of the U.S. health care system—deductibles, networks, and a complicated insurance bureaucracy—that already make it tough for many Americans to afford medical care under normal conditions will likely make the outbreak worse.

More than 140 cases of the coronavirus have been confirmed in the United States so far, according to a Johns Hopkins University tracker. But as the CDC makes the test for the virus more widely available, the structure of the U.S. health care system is complicating the response.

For one, people must actually choose to get tested—a potentially expensive prospect for millions of Americans. While the government will cover the cost of testing for Medicaid and Medicare patients, and for tests administered at federal, state and local public health labs, it’s unclear how much patients will be charged for testing at academic or commercial facilities, or whether those facilities must be in patients’ insurance networks. Just recently, a Miami man received a $3,270.75 bill after going to the hospital feeling sick following a work trip to China. (He tested positive for the seasonal flu, so did not have the new coronavirus, and was sent home to recover.)

Those who test positive for COVID-19 possibly face an even more financially harrowing path forward. Seeking out appropriate medical care or submitting to quarantines—critical in preventing the virus from spreading further—both come with potentially astronomical price tags in the U.S. Last month, a Pennsylvania man received $3,918 in bills after being released from a mandatory U.S. government quarantine after he and his daughter were evacuated from China. (Both the Miami and Pennsylvania patients saw their bills decrease after journalists reported on them, but they still owe thousands.)

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More than 27 million Americans currently do not have health insurance of any kind, and even more are underinsured. But those who do have adequate health insurance are hardly out of the woods. Many current health plans feature massive deductibles—the amount you have to spend each year before your insurance kicks in. In 2019, 82% of workers with health insurance through their employer had an annual deductible, up from 63% a decade ago, according to a report from the Kaiser Family Foundation. The average deductible for a single person with employer insurance has increased 162% in that time, from $533 in 2009 to $1,396 last year.

More than one quarter of employees, and nearly half of those at small companies, have an annual deductible of at least $2,000. Those who are covered by Obamacare marketplace plans face an even bigger hurdle: the average deductible for an individual bronze plan last year was $5,861, according to Health Pocket, a site that helps consumers shop for health insurance.

For many Americans, paying down an unexpected bill of that size is almost unthinkable. Nearly 40% of U.S. adults say they wouldn’t be able to cover a $400 emergency with cash, savings or a credit card they could easily pay off, according to the Federal Reserve.

Research has shown that even in non-outbreak situations, high deductibles lead people to reduce their spending on health care and delay treatment or prescription drugs, which can pose particularly tough problems for patients with chronic illness or diseases that need early detection. The timing of the new coronavirus at the beginning of the year makes the outlook even worse: because most deductibles reset each January, millions of Americans will be paying thousands out of pocket before their insurance companies pay a cent.

“Most likely most people haven’t started paying down their deductible,” explains Adrianna McIntyre, a health policy researcher at Harvard. “For care they seek, unless it’s covered as zero dollar coverage before the deductible, they could be on the hook for the full cost of their visit, the diagnostic testing and other costs related to seeking care or diagnosis of coronavirus.”

Half of Americans report that they or a family member have put off care in the past because they couldn’t afford it. Others have gone without care because they couldn’t find an in-network provider, or couldn’t determine how much care would cost in advance, so decided not to risk seeking medical attention.

“When patients try to go to a doctor or hospital, they often don’t know how much it’s going to cost, so they get a bill that’s way more than expected,” says Christopher Whaley, a health economist at the RAND Corporation. “On a normal basis, that’s chaotic and challenging for patients. But when you add on top this situation where you have a potential pandemic, then that’s even worse.”

In the face of that kind of uncertainty, many patients may simply decide not to go to the doctor, he added, which is “exactly the opposite of what we want to happen in this type of situation.”

Public health experts and Democrats have also criticized the Trump administration’s decision to allow people to sidestep the Affordable Care Act’s rules and buy limited, short-term health insurance coverage. Such “junk plans,” said Senator Patty Murray, speaking at a Senate Health, Education, Labor and Pensions Committee hearing on Wednesday, are not required to cover diagnostic tests or vaccines.

The Trump administration’s embrace of such barebones plans “makes it much harder for people to get the care they need to keep this crisis under control,” she said. A large group of health, law and other experts also released a letter this week urging policymakers to “ensure comprehensive and affordable access to testing, including for the uninsured.”

Insurance industry trade group America’s Health Insurance Plans issued guidance on the coronavirus last week, but it did not recommend that insurance companies eliminate out-of-pocket costs related to the virus. It said insurers would be working with the CDC and “carefully monitoring the situation” to determine “whether policy changes are needed to ensure that people get essential care.”

New York Governor Andrew Cuomo issued a directive on Monday requiring New York health insurers to waive cost sharing for testing of the coronavirus, including emergency room, urgent care and office visits. This could help New Yorkers who receive coverage through Medicaid and other state-regulated plans, but it won’t apply to the majority of employer-based health insurance, which is regulated by the federal government. Other states have similar limitations on the insurance plans they can regulate, according to McIntyre.

The federal government, on the other hand, could step in. The Trump Administration is considering using a national disaster recovery program to reimburse hospitals and doctors for treating uninsured COVID-19 patients. And even Republicans, who have traditionally opposed health care paid for by the government, are warming to the idea. “You can look at it as socialized medicine,” Florida Rep. Ted Yoho, who has vocally opposed the Affordable Care Act, told HuffPost this week. “But in the face of an outbreak, a pandemic, what’s your options?”

But even if the federal government takes steps to eliminate deductibles or other cost-sharing related to the coronavirus, experts say that Americans should brace themselves for long wait times to see providers, or for having to see doctors who are out-of-network, due to the limited capacity of providers and hospitals.

Those who don’t need to be treated at a hospital may still be impacted. The CDC has recommended that people maintain a supply of necessary medications in case they are quarantined, for example. But many insurance companies do not allow patients to refill prescriptions until they are almost out. The CDC also recommends that people to stay home from work if they experience symptoms of respiratory illness, but a lack of federally mandated sick leave makes it impossible for many workers to afford to take time off.

These consequences of the country’s fragmented health care system become more visible in times of stress, says Whaley. “In a pandemic type situation, that’s harmful both for patients,” he says, “and also for the members of society.”

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Write to Abigail Abrams at abigail.abrams@time.com.