The nation's opioid epidemic continues to spiral out of control, with synthetic opiates such as fentanyl continuing to drive the death toll higher, the latest government statistics show.

At least 66,324 people died of drug overdoses during the 12-month period ending in May 2017, up 17 percent from the 56,488 who died between May 2015 and May 2016, according to data released this week by the National Center for Health Statistics.

That's a population roughly equivalent to Union City, New Jersey, or Portland, Maine.

"It's obviously really terrible news," says Christopher Ruhm, professor of public policy and economics at the University of Virginia. "This tells us the situation, if anything, seems to be accelerating."

The new tally backs up provisional estimates, released over the summer, indicating that overdose deaths during the 12-month period ending in May 2017 topped the 58,000 U.S. military deaths that occurred during the Vietnam War.

Deaths from synthetic, non-methadone opioids like fentanyl – 50 to 100 times stronger than heroin – climbed steeply in 2016, rocketing past heroin during the summer of that year.

"This is a problem that until a couple of years ago we associated with prescription opioids," Ruhm says. "Now it has moved into illegal ones, such as heroin and fentanyl."

According to the National Center for Health Statistics, more than 23,000 people died of overdoses of fentanyl and other synthetics, accounting for nearly a third of overdose fatalities in the latest count. That's nearly double the number from the previous 12-month period. During the same period, heroin overdoses accounted for 15,525 deaths; prescription painkillers, such as OxyContin and Percocet, were linked to 14,647 deaths.

The agency's data are provisional, drawn from death certificates entered into the National Vital Statistics System from the 50 states and Washington, D.C. The actual totals are likely to be even higher because up to 5 percent of cases in some jurisdictions may still be under investigation.

Data released this week in America's Health Rankings, a state-level health rankings project sponsored by the United Health Foundation, offers another window into the nation's escalating drug problem. The rankings also rely on data from the Centers for Disease Control and Prevention's NCHS, but analysis tallies drug death rates overall and by state.

Nationwide, drug deaths rose 7 percent in the last year from 14 to 15 per 100,000. The drug death rate among men is 18.7 deaths per 100,000, significantly higher than the rate for women at 11.3 deaths per 100,000 population.

Over the past five years, the biggest increases in drug deaths have occurred in Massachusetts, Rhode Island, Ohio, New Hampshire and West Virginia.

Massachusetts represents a tragic paradox, says Dr. Rhonda Randall, chief medical officer for UnitedHealthcare Retiree Solutions. Perennially ranked among the healthiest states, Massachusetts has the highest concentration of mental health professionals in the U.S. – a total of 547 per 100,000 residents – yet it also had a 69 percent increase in drug deaths over the last five years.

The state's soaring rate, Randall says, raises critical questions about what's being done there to bring the epidemic under control and to help those affected by it.

Ruhm says that federal, state and local health officials may be vocal about the magnitude of the problem – in October, President Donald Trump declared opioid addiction a public health crisis – but they're not taking adequate steps to bring the epidemic under control.

"We're in the process of passing enormous tax cuts that are going to raise the federal deficits," Ruhm says. "They're going to need to cut Medicare and Medicaid to address the budget crisis they're creating. That's not the response I would hope to see."

One remedy that shows promise are lawsuits brought against opioid producers and distributors by persons injured by opioids and by federal, state and local governments and Native American tribes, report Rebecca Haffajee of the University of Michigan School of Public Health in Ann Arbor and Michelle Mello of Stanford University Law School. A class action lawsuit filed against Purdue Pharma in Canada by patients who were prescribed, and took, OxyContin and controlled-release oxycodone may soon be settled for $20 million, if all involved provinces agree. The Canadian plaintiffs' allegations are similar to those in many U.S. cases, the authors say.