How effective is Shingrix?

In this article:

• How does Shingrix work?
• Shingrix efficacy
• Shingrix dosage schedule
• How effective is one dose of Shingrix?
• What happens if you don't get a second Shingrix shot?

In this article

• How does Shingrix work?
• Shingrix efficacy
• Shingrix dosage schedule
• How effective is one dose of Shingrix?
• What happens if you don't get a second Shingrix shot?

Shingles isn’t necessarily a household name, but statistically speaking, it’s more common in the United States than heart disease, diabetes, and asthma. According to the CDC, 1 in 3 Americans will get Shingles in their lifetime. This rash-causing virus is certainly prevalent, but it’s also avoidable thanks to immunizations like Shingrix. Millions of people have already received at least one dose of this shingles vaccine—but does it actually work?

For most people, yes. Shingrix has been over 90% effective in preventing shingles for older adults. Here’s all the information you need about how Shingrix works and what makes it so effective.

How does Shingrix work?

Shingles (herpes zoster) comes from the varicella-zoster virus, the same one that causes chickenpox. Even after the chickenpox illness resolves, this virus lies dormant in the nervous system. Occasionally, it can reactivate, causing a painful rash, also known as shingles.

Shingrix contains dead pieces of this virus, called antigens, and adjuvant proteins, which allow the immune system to bolster its defenses against it. “By injecting adjuvants and [antigens], the body can remember the infection and thus B and T cells can make a response to the infection,” said Ben Gibson, Pharm.D., a pharmacist, speaker, and medical writer.

Essentially, once the immune system is familiar with the virus, it will know how to fight it. Shingrix is administered in two doses, each comprising one vial of antigen, reconstituted with one vial of adjuvant suspension.

Shingrix efficacy

The Centers for Disease Control and Prevention (CDC) recommends Shingrix for everyone 50 years and older because it’s shown excellent efficacy in clinical trials that demonstrated a high percentage of efficacy among the following age groups:

• Ages 50–59: 96.6%
• Ages 60–69: 97.4%
• Ages 70–79: 90.0%
• Ages 80 and older: 89.1%

For immunocompromised adults, those numbers drop to 68%–91% efficacy, depending on their underlying condition. Shingrix also showed 91.2% vaccine efficacy in preventing postherpetic neuralgia (PHN) for adults over 50, and 88.8% efficacy for adults over 70.

So it works, but the CDC says patients report that it might also cause some side effects. In fact, around 1 out of 10 patients report injection site pain, redness, and swelling. And 1 out of 10 also report adverse events like muscle aches, fatigue, headaches, shivering, fever, and gastrointestinal illness. That said, these effects are typically only temporary.

Additionally, the Food and Drug Administration (FDA) requires a warning in the prescribing information that Shingrix can cause Guillain-Barré syndrome—a serious autoimmune disorder where the body attacks its own peripheral nerves. Fortunately, it’s pretty rare. One study found only three excess cases of Guillain-Barré syndrome per million doses of Shingrix.

RELATED: Getting the Shingrix vaccine—is it worth it?

Shingrix dosage schedule

Like some other vaccines, Shingrix comes in two doses. “The standard recommendation to administer the second dose of Shingrix is two to six months after the first dose. This interval is crucial to build a strong and effective immune response,” said Soma Mandal, MD, a board-certified internist at Summit Health. The CDC recommends getting both doses, even if you’ve had Zostavax, a herpes zoster vaccine that’s no longer in use, since Shingrix provides stronger protection. 

Within that two-to-six-month window, the exact timing depends on the patient’s overall health. “If the patient is experiencing any severe illness or acute infection, it may be advisable to delay the second dose until the patient has recovered. If a patient had a severe allergic reaction to the first dose of Shingrix, the second dose should not be given. If a patient has a weakened immune system, the timing of the second dose may need to be adjusted,” Dr. Mandal said. Most people can wait up to six months, although immunocompromised people may want to get their next dose within one to two months. If the second dose is delayed longer than six months, it can still be given without repeating the first dose.

The CDC says the vaccine’s immunity lasts for at least seven years, and certain studies suggest it might last up to ten. After that, your protection may be less robust, although it’s best to consult your healthcare provider to know for sure.

How effective is one dose of Shingrix?

According to KFF data, in 2018, 74% of Medicare Part D beneficiaries had received their second dose of Shingrix within six months of getting their first dose. So what about the 26% who just got the first one? Odds are, it’ll still reduce the risk of shingles and postherpetic neuralgia, but not quite as much. “The first dose helps the immune system start building protection against the shingles virus,” Dr. Mandal said. “While the second dose boosts that production.”

There are limited studies on the efficacy of a single dose, but studies have concluded that one dose had only 69.5% vaccine effectiveness in adults over 70. The authors noted, however, that the time frame for this study was fairly short, since most of the subjects proceeded to get their second dose.

What happens if you don’t get a second Shingrix shot?

Whether about the potential side effects of Shingrix or because life just got hectic, some people miss their second dose. If it’s been longer than six months since your first dose, don’t panic. You don’t need to start over. Instead, just get the second one as soon as you can. “But after a year, said Dr. Gibson, “a single dose doesn’t have as much benefit, as displayed by a study where patients waited two, six, and twelve months before getting their second dose.”

“Since Shingrix is a two-dose vaccine, both doses are necessary to provide the highest level of protection against shingles. If someone doesn’t get two doses, they may not be fully protected,” said Dr. Mandal.