Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. In a cohort of Medicare beneficiaries, the recombinant zoster vaccine was associated with a slightly increased risk of Guillain-Barré Syndrome.

Evidence Rating Level: 2 (Good)

After evaluation of vaccinations for herpes zoster, the recombinant zoster vaccine (RZV) was recommended over the zoster vaccine live (ZVL) for prevention. Guillain-Barré Syndrome is an immune-mediate polyneuropathy that has been reported following certain vaccinations, including RZV. Therefore, this retrospective cohort study aimed to investigate GBS risk after receiving the RZV vaccine. The study utilized data from Medicare enrollment and claims databases. It identified a total of 1,318,004 recipients of RZV vaccinations and 1,817,099 patients who received ZVL vaccinations. Amongst RZV recipients, the mean age was 74.8 years and 58% were female whereas those receiving the ZVL vaccine had a mean age of 74.3 and 60% were female. It was found that GBS risk after RZV is increased compared to ZVL (RR, 2.34; 95% CI, 1.01 – 5.41; p = 0.047. The study also performed a self-controlled case series analysis for those receiving RZV. A risk window was defined as 1 to 42 days postvaccination and served as a “case”, while the control window was defined as 43 to 183 days postvaccination. It was found that there was an increased risk of GBS in the risk window compared to the control window (RR, 4.30; 95% CI, 1.76 – 10.53; p = 0.001). The secondary analysis found an increased risk of GBS after the first RZV dose (RR, 9.30; 95% CI, 3.00 – 28.84; p <0.001). There were 9.50 excess cases (95% CI, 4.35 – 14.66; p <0.001) for every million vaccinations administered. Therefore, the study concluded that there may be a slightly increased risk of GBS for 42 days following RZV vaccination, however, these should be measured against risk of herpes zoster and its complications. This was a well-powered study and thus helps to answer an important clinical question.

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