A slight increased risk of Guillain-Barré syndrome (GBS) was observed during the 42-day period following recombinant zoster vaccination (Shingrix) in Medicare beneficiaries. However, despite this risk, researchers suggest the benefits of the vaccine likely outweigh the risks associated with the varicella zoster virus itself. This is according to study findings published in JAMA Internal Medicine.

GBS is a rare disorder that leads to muscle weakness and paralysis affecting 3,000 to 6,000 people in the United States each year. This autoimmune disorder has also been reported following certain vaccinations, such as the recombinant zoster vaccine. The objective of the current study was to evaluate the risk for GBS following vaccination with the zoster vaccine using Medicare claims data.

The study was a case series that included Medicare beneficiaries aged 65 years or older who had been vaccinated with either the recombinant zoster vaccine (n=849,397; mean age, 74.8 years) or zoster vaccine live (n=1,817,099; mean age, 74.3 years). A self-controlled case series analysis included events from 2,113,758 eligible recombinant zoster-vaccinated beneficiaries aged 65 years or older.


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The researchers compared the relative risk of GBS in the days following the recombinant versus zoster vaccine live and also performed claims- and medical record-based self-controlled case series analyses to evaluate the risk of the autoimmune disorder during days 1 through 42 after vaccination vs with a postvaccination control window consisting of days 43 through 183.

Compared with the zoster vaccine live group, there was an increased risk of GBS in people who received recombinant zoster vaccines (rate ratio [RR], 2.34; 95% CI, 1.01-5.41; P =.047). There were 24 cases and 20 cases of GBS during the risk and control period, respectively, in the self-controlled analyses. In the primary analysis of the self-controlled case series analysis, the researchers found an increased risk of the disorder in the 42-day risk window after vaccination vs the control window (RR, 4.30; 95% CI, 1.76-10.53; P =.001).

In the claims-based analysis, the researchers identified an increased risk of GBS in the risk window compared with the extended control window (RR, 2.84; 95% CI, 1.53-5.27; P =.001). There was an attributable risk of 3 per million recombinant zoster vaccine doses (95% CI, 0.62-5.64). When comparing incidence in risk and control windows in the medical record–based analysis, the researchers again found an increased risk of GBS (RR, 4.96; 95% CI, 1.43-17.27; P =.01).

They noted that the analyses did not adjust for preceding diseases or other time-varying confounders, which may limit the findings. Additionally, the researchers explained that the risk window following recombinant zoster vaccination was “not as well defined as the risk window” after influenza vaccination, and they were likewise unable to determine an ideal risk window with scanning statistics. In addition, the study included only individuals aged 65 years and older, which may limit the generalizability of the findings across all patients eligible for vaccination.

The researchers wrote “despite the elevated risk of GBS observed” in their study, both clinicians and patients “should be aware of the risk of GBS, and consider the benefits of avoiding zoster with an efficacious vaccine.”

Reference

Goud R, Lufkin B, Duffy J, et al. Risk of Guillain-Barré Syndrome following recombinant zoster vaccine in Medicare beneficiaries. JAMA Intern Med. Published online November 1, 2021. doi:10.1001/jamainternmed.2021.6227