America is currently mired in the worst drug epidemic in history, as tens of thousands die every year from overdoses linked to opioid painkillers, synthetic opioids, and heroin. And now President-elect Donald Trump and Republicans in Congress are considering a move that could make this huge public health crisis even worse.

That move is the potential repeal of the Affordable Care Act (ACA or “Obamacare”). Depending on how GOP lawmakers eliminate the health care law, it could jeopardize health insurance for as many as 22 million people. For those with drug use disorders, that’s particularly harmful — many rely on health insurance not just for their annual checkups and hospital visits, but their day-to-day care for drug abuse treatment.

Now two new reports released Wednesday put numbers to just how many people with drug use disorders could be left to suffer without care.

One of the reports, from researchers at Harvard Medical School and New York University, found that Obamacare’s repeal could increase the opioid treatment gap by 50 percent. Under Obamacare, the federal government has estimated that about 420,000 people with opioid use disorders couldn’t or didn’t get treatment. The new analysis found that if Obamacare is repealed without a complete replacement that covers the health care needs of people with drug use disorders, the total would increase by 220,000 — to about 640,000.

“That’s 220,000 people who have an opioid use disorder who now wouldn’t have access to treatment,” Richard Frank, one of the co-authors of the report, told me, “when we’re actually trying to go the other way.”

The other report, from the US Department of Health and Human Services (HHS), outlines what the potential risks of Obamacare’s repeal are for patients with drug use disorders. The report found that the states likely to see the biggest losses in insurance coverage are also some of the states hit hardest by the opioid epidemic — particularly Kentucky, Massachusetts, New Hampshire, Ohio, Rhode Island, and West Virginia.

“According to Urban Institute estimates, four states — Massachusetts, West Virginia, Kentucky, and New Hampshire — would see their uninsured rates nearly or more than triple if the ACA were repealed,” the report found. “These four states ranked 7th, 1st, 3rd, and 2nd respectively in drug overdose death rates in 2015, according to CDC data.”

This would amount to a return to the days before Obamacare, when more patients for drug use disorders lacked health insurance. According to the HHS report, 14 percent of hospitalizations for substance use or mental health disorders in 2014 involved someone who lacked insurance, down from 22 percent in 2013, which is just before Obamacare’s major insurance expansion provisions kicked in.

The difference is even more stark for states that expanded Medicaid, which provides insurance to low-income Americans and people with disabilities, under Obamacare: The amount of hospitalizations for substance use or a mental health disorder in which the recipient was uninsured fell from about 20 percent toward the end of 2013 to about 5 percent by mid-2015.

“People with these illnesses benefited more than others did having the act,” Frank said. “They’re also going to be the ones that lose more if you start scaling it back.”

So there’s strong evidence that Obamacare has provided insurance for a lot of people with mental health and drug use disorders, including people who need care for opioids in particular. And if Obamacare is taken away, these people are going to lose out — as a drug epidemic ravages much of the country.

The Republican replacement plans don’t look likely to make up the difference

If the Republican replacement to Obamacare doesn’t adequately cover these people, they’re going to be much less likely to be able to afford care for drug use disorders.

So far that’s exactly what looks likely to happen. While Trump and Republicans have vowed to repeal Obamacare, they haven’t outlined a specific plan just yet. But the plans they have specified always leave a greater number of people of uninsured — anywhere from 3 million to 21 million, depending on the plan.

And even for those getting coverage, it’s not clear whether treatments for drug use disorders will be covered under Republican replacement plans. Obamacare deems “mental health services and addiction treatment” an “essential health benefit” that’s to be included in individual market plans, small group plans, Medicaid, and Medicare. But Republicans have called Obamacare’s 10 essential health benefits too stringent, making them a major target for repeal in replacement plans — and that will likely result in fewer health insurers including addiction treatment in their coverage.

“One thing history teaches us is the first things that get jettisoned are mental health and addiction treatment,” Frank said.

Beyond the opioid epidemic, Frank’s analysis found nearly 1.3 million people with serious mental health disorders and 2.6 million people with non-opioid drug use disorders would lose some or all of their health insurance.

Trump’s team did not respond to questions about how the president-elect would help victims of the opioid epidemic get care if Obamacare is repealed. Previously, Trump has vowed to provide treatment for people caught in the opioid epidemic — but he hasn’t offered specifics for how, exactly, he would accomplish that.

Meanwhile, the opioid epidemic is linked to tens of thousands of overdose deaths each year.

The opioid epidemic began with a legal drug

In 2015, more Americans died of drug overdoses than any other year on record — more than 52,000 deaths in just one year. That’s higher than the more than 36,000 who died in car crashes, the more than 36,000 who died from gun violence, and the more than 43,000 who died due to HIV/AIDS during that epidemic’s peak in 1995.

This latest drug epidemic, however, is not solely about illegal drugs. It began, in fact, with a legal drug.

Back in the 1990s, doctors were persuaded to treat pain as a serious medical issue. There’s a good reason for that: About one in three Americans suffer from chronic pain, according to a 2011 report from the Institute of Medicine.

Pharmaceutical companies took advantage of this concern. Through a big marketing campaign, they got doctors to prescribe products like OxyContin and Percocet in droves — even though the evidence for opioids treating long-term, chronic pain is fairly weak, despite their effectiveness for acute, short-term pain. Painkillers proliferated, landing in the hands of not just patients but also teens rummaging through their parents’ medicine cabinets, other family members and friends of patients, and the black market.

So opioid overdose deaths trended up — sometimes involving opioids alone, other times involving drugs like alcohol and benzodiazepines (typically prescribed to relieve anxiety). By 2015, they totaled more than 33,000 — close to two-thirds of all drug overdose deaths.

Seeing the rise in opioid abuse and deaths, officials have cracked down on prescriptions painkillers. Law enforcement, for instance, threatened doctors with incarceration and the loss of their medical licenses if they prescribed the drugs unscrupulously.

Ideally, doctors should still be able to get painkillers to patients who truly need them — after, for example, evaluating whether the patient has a history of drug abuse. But doctors who weren’t conducting even such basic checks are now being told to give more thought to their prescriptions.

Yet many people who lost access to painkillers were still addicted. So some who could no longer access prescribed painkillers — or perhaps could no longer afford them — turned to cheaper, more potent opioids: heroin and fentanyl, a synthetic opioid that’s often manufactured illegally for non-medical uses.

Not all painkiller users went this way, and not all opioid users started with painkillers. But statistics suggest many did: A 2014 study in JAMA Psychiatry found many painkiller users were moving on to heroin, and a 2015 analysis by the Centers for Disease Control and Prevention found that people who are addicted to prescription painkillers are 40 times more likely to be addicted to heroin.

So other types of deadly opioid overdoses, excluding painkillers, also rose.

That doesn’t mean cracking down on painkillers was a mistake. It appeared to slow the rising number of painkiller deaths, and it may have prevented doctors from prescribing the drugs to new generations of potential addicts.

But the likely solution is to get opioid users into treatment. According to 2014 federal data, at least 89 percent of people who met the definition for a drug abuse disorder didn’t get treatment. Patients with drug abuse disorders also often complain of weeks- or months-long waiting periods for care.

So federal and state officials have pushed for more treatment funding, including medication-assisted treatment like methadone and Suboxone. Obamacare has played a key role in this effort, unlocking access to care for millions of people.

Some states, like Louisiana and Indiana, have taken a “tough on crime” approach that focuses on incarcerating drug traffickers. But the incarceration approach has been around for decades — and it hasn’t stopped massive drug epidemics like the current opioid crisis.