Have Medicare? The shingles vaccine will cost you.

When Stanley Isenberg learned there was a new shingles vaccine, he set out to find it.

Having seen how his father suffered with the painful, blistered rash of shingles, he wanted to avoid that fate at all costs.

Isenberg, a 94-year-old World War II veteran, was prepared to pay. But he was still shocked by the price the pharmacist quoted for the first in the two-shot series: $167.

"I said, 'Wow!' " Isenberg recalled.

The pharmacist shrugged. Isenberg chewed on the number, thought about his father, then rolled up his sleeve and replied, "Let's go."

Shingrix, made by GlaxoSmithKline, has been in such high demand since it was released last year that many pharmacies have had a hard time keeping it in stock. But if you're lucky enough to track it down and you are covered by Medicare, be prepared to pay dearly.

Under the Affordable Care Act, most private insurance plans are required to cover the vaccine with no copay or coinsurance when administered by an in-network provider.

But for Medicare beneficiaries, the cost will vary depending on what type of drug coverage you have. People with traditional Medicare may purchase a separate Part D drug plan, while Medicare Advantage plans sold by private insurers typically include prescription coverage. Each plan may cover the vaccine differently. You may have a copay to get the vaccine and an additional fee if you haven't yet met your deductible. Because you need two shots, you'll pay twice.

"The prices are all over the map," said Sue Greeno, a Medicare advocate with the Center for Medicare Advocacy in Washington. "I strongly advise people if they're considering this to check with their plan if it's on their covered list of drugs."

The annual open enrollment period, when Medicare beneficiaries can change their plans if they find one that better meets their needs, ends on Dec. 7, so it may be worth checking now to see how your plan covers Shingrix.

The U.S. Centers for Disease Control and Prevention recommends everyone over age 50 who had chicken pox — which is how the virus that can lead to shingles gets in the body — get two doses of Shingrix. The vaccine is 97 percent effective in preventing shingles among people aged 50 to 69.

People should get Shingrix even if they already received Zostavax, an earlier and much less effective shingles vaccine made by Merck.

The CDC recommends getting the second shot between two and six months after the first. If you're not able to get the second shot in that window, get it as soon as you can — you won't have to start the regimen over, according to the CDC. Use the website www.vaccinefinder.org if it's out of stock at your regular pharmacy.

Demand for the vaccine has exceeded expectations and left GSK scrambling to ramp up production.

GSK distributed as many doses in July, August, and September as it did in the first six months of the year. As of September, nearly seven million doses of Shingrix have been administered globally since it was released in November 2017, according to the company. The majority of those doses were given in the U.S., where Shingrix became available in June.

GSK is working on shortening the vaccine's production time — currently six to nine months — to get more of it to pharmacies. Over the next few years, the company expects to supply doses "in the high teens millions" annually, said Sean Clements, a GSK spokesperson, in a statement.

"We understand that this is a challenging situation to manage and GSK is fully committed to expediting Shingrix resupply," Clements said.

Before turning to the pharmacy in August, Isenberg tried to get the vaccine at the Philadelphia VA Medical Center, but it was all out.

When he was due for his second shot, Isenberg first returned to the pharmacy where he'd gotten his first dose, but they didn't have it. Next, he tried a different VA medical center, closer to his new home in Audubon, Pa.

This time, he was in luck.

"The doctor said, 'We have the vaccine and your time is now, so roll up your sleeve,' " Isenberg said.

Veterans receive the shingles vaccine at no cost at VA medical centers, the agency said.

Isenberg said he had been willing to fork over $167 for the first shot and was prepared to pay for the second because he knows it's important. Still, the no-charge shot from the VA medical center was a relief.

"Why? Why so expensive?" Isenberg said.

The shortages, the vaccine's effectiveness, and the fact that Shingrix is a brand-name drug with no competitors have all contributed to its price tag, said Thomas Goetz, chief of research at GoodRx, an online drug price comparison tool.

"It's not an incremental improvement — it's a material difference, in terms of efficacy," Goetz said. "There's a market for that and there's one manufacturer, so they can put their price on it. They hold a lot of cards in the negotiations with insurers."

Shingrix is covered by more than 90 percent of private insurance and Medicare drug plans. The vast majority of people with private insurance who get the vaccine at an in-network pharmacy have an out-of-pocket cost of no more than $10 per shot. People with Medicare Part D pay an average of $50 per shot, according to GSK.

But that's an average. Members' out-of-pocket cost can vary greatly from one plan to the next, even though it is a covered drug.

"For other services like hospitalizations or doctor services, Medicare has a price it's willing to pay that's often lower than what we might see in the non-Medicare private commercial market," said Juliette Cubanski, associate director of the Kaiser Family Foundation's program on Medicare policy.

That's not the case for prescription medications, which aren't covered by traditional Medicare. Standalone drug plans and Medicare Advantage plans that include drug benefits all negotiate prices for medications individually. The federal government can dictate which drugs must be included in drug formularies, but it is up to the insurers that sell those plans to decide how much to charge, she said. The overall Medicare program, by act of Congress, is forbidden to negotiate drug prices.

According to GoodRx, Medicare members pay anywhere from zero to $153 for each Shingrix shot. The retail price is about $180 per shot.

"That's a huge range, and that's where people get especially frustrated. Their friends or neighbors may be getting the vaccine for little to nothing, whereas their Part D is hitting them up with a copay," Goetz said.

He recommends checking with your plan in advance to find out how much to expect to pay for the shot and compare the price at different pharmacies. Prices can vary by pharmacy, too.

If the cost will be significant, find out whether you qualify for financial assistance.

People with private insurance and incomes less than 250 percent of the federal poverty level can qualify for GSK's patient assistance program.

Medicare beneficiaries must also have spent $600 out-of-pocket on medications to qualify for the assistance program, in addition to meeting income requirements.

Other Medicare discount programs funded by the federal government and states can also help cover medication and premium costs, Greeno said. Contact Medicare or your state health insurance assistance program (www.shipacenter.org) to find out if you're eligible for a Medicare Savings Program.

Even though Medicare drug coverage plans do change what they cover from year to year, many people don't take advantage of the opportunity to switch during open enrollment. But even those who do reexamine their plan may be less likely to think of a vaccine than the medications they take daily when evaluating drug costs, Greeno said.

"People often shop for plans based on the plan name, but they don't realize that's much less important than what kind of out-of-pocket costs they're going to have," she said.