DULUTH — If you’re older than 50 and you’ve ever had the chickenpox, the good news is that the latest vaccine against shingles is very effective.

The bad news is that you’ll probably have to wait to get it.

“We need to plan (for shortages) throughout 2019,” said Gina Lemke, director of pharmacy at St. Luke’s.

Shortages of pharmaceuticals and medical equipment have become an increasing symptom of the U.S. medical system. As of this week, the American Society of Health-System Pharmacists listed shortages of 200 drugs.

In the case of the vaccine known as Shingrix, it was in short supply right out of the gate.

“Even before we could order it, our doctors were clamoring: ‘When can we get it?’ ” Lemke said. “There was a built-up demand before it was out on the market.”

The British pharmaceutical giant GlaxoSmithKline won FDA approval for Shingrix in October 2017. By the end of this September, nearly 7 million doses were administered, according to a GlaxoSmithKline statement. The vast majority were in the United States.

GlaxoSmithKline’s statement suggests that the company was caught off guard.

“Shingrix has been met by unprecedented demand by health care providers and patients,” it reads. “Providers are immunizing patients at a rate several times what was previously seen for shingles.”

Why is it so in demand?

For one thing, shingles — aka herpes zoster — is a common ailment. Anyone who has had chickenpox can get shingles, according to the U.S. Centers for Disease Control and Prevention, although it’s more likely to occur as we get older. In the U.S., one out of every three of us will get it, and about a million people get it each year.

Second, it’s no fun. The main symptom is a painful rash that can take two to four weeks to clear up, according to the CDC.

“People are definitely afraid of getting shingles,” said Ann Philbrick, an associate professor at the University of Minnesota College of Pharmacy.

Third, the vaccine is really good. The Advisory Committee on Immunization Practices found it to be better than 95 percent effective for people aged 50-69 and better than 90 percent for people aged 70 and older.

The CDC recommends that even people who had the previous vaccine for shingles get Shingrix, Philbrick said.

“I definitely think it’s a better vaccine,” she said. “It’s more effective, and it appears that it’s going to last longer.”

But unlike the previous vaccine, Shingrix requires two doses; the CDC recommends that they take place between two and six months apart. Because of that, Lemke said, pharmacists want to make sure there’s sufficient supply so that when a person gets the first dose, a second dose also will be available within six months.

Earlier this year, GlaxoSmithKline said its goal was to be caught up by January or February, Philbrick said. “(Then) they stopped giving that time frame.”

In its statement, the pharmaceutical company says it’s doing its best. They’ve been shipping “large amounts” of the vaccine every two to three weeks and will regularly ship it twice a month beginning this month. They distributed as many doses in July, August and September as they did in the previous six months. Over the next two to three years, GlaxoSmithKline expects to build its supply to “the high teens millions”

Nonetheless, the statement concludes, “ordering limits” are expected to continue throughout 2019.

All of which means that if you want to get the Shingrix vaccine, you’ll likely spend time on a waiting list.

“I think the overall message is just to hold tight,” Lemke said. “Make sure they get on the list. They will get the vaccine. We just have to wait out the upcoming months.”

While you’re waiting, one thing to keep in mind about that shot: It hurts.

“I would say about three-quarters of patients complain of severe pain at the injection site,” Philbrick said, later adding: “It’s a heck of a shot.”

Finding the vaccine

Patients can use the “Shingrix vaccine finder” at shingrix.com to locate provider or pharmacies that are offering the vaccine, according to GlaxoSmithKline.