Risk of Guillain-Barre Syndrome Higher with Recombinant Zoster Vaccine Shingrix

The recombinant zoster vaccine Shingrix carries a greater risk of Guillain-Barre syndrome than zoster vaccine live Zostavax, a recent observational study of Medicare beneficiaries found.

The study, published in JAMA Internal Medicine, included 849,397 Medicare beneficiaries aged 65 and older who received the recombinant zoster vaccine (RZV or Shingrix) and 1,817,099 who received the zoster vaccine live (ZVL or Zostavax).

In the cohort analysis, the risk of Guillain-Barré syndrome adjusted for age and sex was greater among those who received the RZV compared with the ZVL vaccine (rate ratio [RR], 2.34; 95% CI, 1.01-5.41; P = .047).

The study also included a claims-based analysis, which identified an increased risk of GBS (RR, 2.84; 95% CI, 1.53-5.27; P = .001), with an attributable risk of 3 per million RZV doses (95% CI, 0.62-5.64), which was confirmed by a medical record–based analysis (RR, 4.96; 95% CI, 1.43-17.27; P = .01).

“Our findings confirm a slightly increased risk of GBS during the 42 days following RZV vaccination in the Medicare population, with approximately 3 excess GBS cases per million vaccinations,” corresponding author Ravi Goud, MD, MPH, of the Center for Biologics Evaluation and Research at the US Food and Drug Administration told Contagion®. “GBS can occur after herpes zoster itself too, as several observational studies have also suggested an increased risk of GBS associated with herpes zoster reactivation. Prevention of herpes zoster and potentially subsequent GBS should also be considered when weighing the benefits of the vaccine.”

The FDA approved the Shingrix vaccine in October 2017 for adults age 50 and older after it was found to reduce the risk of herpes zoster by 97.2% in participants aged 50 years or older and 89.8% in participants aged 70 years or older when compared with placebo. The two-dose vaccine is taken two to six months apart. In July, the FDA expanded approval of the vaccine to include adults aged 18 years and older with increased risk of immunodeficiency or immunosuppression, among the most common risk factors for shingles.

“This study shows the value of large active surveillance systems to identify and characterize rare risks associated with medical products,” Goud said.

The study was a collaboration between the FDA, the Centers for Medicare and Medicaid Services and the Centers for Disease Control and Prevention using Medicare claims data and the Vaccine Safety Datalink. Investigators identified cases of GBS after RZV vaccination from Oct. 1, 2017, to Dec. 31, 2018, and compared them to cases of GBS when ZVL was administered between Oct. 1. 2012, and Sept. 30, 2017.

Mean age of participants who received the RZV vaccine was 74.8 years at first dose, and 58% were female, compared with a mean age of 74.3 years, and 60% female for the ZVL vaccine.

Studies are ongoing, including post-marketing commitment studies and safety surveillance.

“It is important to note that no change to vaccine guidance is necessary,” Goud said. “The package insert was updated on March 24, 2021, to convey the risk of GBS post-vaccination. The Advisory Committee on Immunization Practices (ACIP) is aware of the increased risk of GBS after Shingrix vaccination and that benefit continues to outweigh risk.

“Providers and patients should be aware of this risk, while considering the benefit of decreasing the risk of herpes zoster and its complications through an efficacious vaccine, as benefit-risk balance remains in favor of vaccination. Patients should continue to get vaccinated to accrue the benefits of avoiding herpes zoster reactivation, but they should seek treatment should any symptoms of GBS develop.”