FDA Adds Guillain-Barré Syndrome Warning to GSK’s Shingrix Vaccine Label

Compiled by Keke

GlaxoSmithKline (GSK) Adds New Safety Warning to Label of Shingrix, Its Blockbuster Vaccine, While Regulators Maintain That Benefits Outweigh Risks

This Wednesday (March 24), the U.S. Food and Drug Administration (FDA) alerted the public that it has added a warning to the "Warnings and Precautions" section of the Shingrix shingles vaccine label regarding the risk of developing Guillain-Barré Syndrome (GBS), a rare neurological autoimmune disorder.

Previously, a post-marketing observational study by U.S. federal health agencies indicated a risk of developing this condition within 42 days after Shingrix vaccination. However, the U.S. FDA emphasized that “the existing evidence is still insufficient to establish causality” and that “the benefits of Shingrix vaccination continue to outweigh its risks.”

In short, the association between the vaccine and this rare disease has not changed the U.S. FDA’s view that “Shingrix is safe.”

In a statement, GSK said it “remains confident in the favorable benefit-risk profile of Shingrix for the prevention of herpes zoster.” The company will continue to collaborate with the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) to monitor the post-marketing safety of Shingrix.

The U.S. FDA analyzed data from nearly 3.73 million Shingrix vaccinations administered between October 2017 and February 2020, based on Guillain-Barré syndrome (GBS) cases reported among Medicare beneficiaries in the CDC’s Vaccine Safety Datalink system.

Compared with historical data for Merck’s older zoster vaccine, Zostavax, the U.S. FDA found that within 42 days after vaccination, three cases of this rare syndrome occurred per million doses of zoster vaccine administered in adults aged 65 years or older. Shingrix is administered in two doses, with an interval of 2 to 6 months between doses.

This increased risk of disease appears to be caused by the first dose. The U.S. FDA noted that within 42 days after the first vaccination, an estimated 6 cases of GBS occur per million vaccine doses, while no increased risk of GBS was observed after the second vaccination.

Prior to post-marketing studies, Guillain-Barré syndrome (GBS) was not identified as a potential safety concern for Shingrix in the clinical trials that led to its approval in 2017.

Guillain-Barré syndrome (GBS) is a rare but potentially life-threatening condition in which the body’s immune system attacks nerve cells. It most commonly occurs following a viral or bacterial infection. Shingrix, a vaccine designed to prevent herpes zoster (shingles), has been associated with multiple secondary cases of GBS. According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 3,000 to 6,000 people develop this syndrome each year.

GBS has also been associated with other vaccine products, including the H1N1 influenza vaccine. However, a 2013 study investigating cases at Kaiser Permanente Northern California in the United States from 1995 to 2006 found a weak association between GBS and routine vaccination.

GSK also stated in its announcement that an analysis presented at the February meeting of the CDC’s Advisory Committee on Immunization Practices (ACIP) provided recommendations for vaccination with this vaccine. The agency’s shingles working group supports routine vaccination with Shingrix in individuals aged 50 years and older. They noted that existing data, including those from observational studies, are limited regarding the risk of Guillain-Barré syndrome (GBS) following herpes zoster infection or vaccination.

Reference source: FDA slaps new warning on GlaxoSmithKline's Shingrix based on post-marketing findings