In a safety communication the U.S. Food and Drug Administration (FDA) has ordered manufacturers of two respiratory syncytial virus – RSV Vaccines to include warnings about the risk of Guillain-Barré syndrome (GBS) on their product labels. This decision affects GSK’s Arexvy and Pfizer’s Abrysvo vaccines, both approved for use in adults to prevent lower respiratory tract disease caused by RSV.
RSV is a common respiratory virus that typically causes mild, cold-like symptoms but can lead to severe outcomes, especially in infants and older adults. The FDA approved Arexvy in May 2023 for use in adults aged 60 and older for lower respiratory tract disease from RSV and subsequently also approved it for individuals 18 through 59 years for those with an increased risk for it as well as for use in pregnant women in the hope to protect infants from birth through six months of age. FDA approved Abrysvo in May 2023 for prevention of lower respiratory tract disease caused by RSV in individuals 60 years and older and later also approved it for use for those at increased risk in the age of 50 through 59 years.
New Warning Requirements
The FDA now requires the following statement to be included in the Warnings and Precautions section of both vaccines’ prescribing information: “The results of a postmarketing observational study suggest an increased risk of Guillain-Barré syndrome during the 42 days following vaccination with [Abrysvo/Arexvy]”.
This takes place after FDA conducted a postmarketing observational study using Medicare data, which estimated an increase by 9 excess cases of GBS per million doses of Abrysvo and 7 excess cases of GBS per million doses of Arexvy. These estimates were for individuals aged 65 and older, within 42 days following vaccination.
Guillain-Barré Syndrome (GBS) is a neurological disorder in which the body’s immune system attacks nerve cells, causing muscle weakness, sensory abnormalities, autonomic dysfunction and sometimes paralysis. Symptoms typically start with weakness and tingling in the legs, potentially progressing to the arms and upper body. It can lead to a near-total paralysis.
Vaccines associated with this nerve damage
As it is believed that GBS is a dysfunction of the immune stimulation and as vaccines have an effect on the immune system it is biologically plausible that immunizations may be associated with GBS. Indeed, several vaccines have been found to have an association with Guillain-Barré syndrome. Vaccines like the modern Influenza vaccines have been found with an approximately 1 additional GBS case increase per million vaccinations, the Swine flu vaccine from 1976-1977 has showed the strongest causal association with GBS 2 while rabies vaccines with formulations cultured in mammalian brain tissues were associated with increased GBS risk. Today chick embryo cell-derived vaccines do not appear to have this association.
Some reports suggest a possible link for the Shingles vaccine though specific recommendations for those with a history of GBS are not in place. In fact, a recent study found significant associations between most vaccines and GBS, except for rotavirus and tuberculosis vaccines. However, these associations are generally temporal rather than causal, and the overall risk is deemed to remain low.
And then there are the COVID-19 vaccines. Regardless of vaccine technology used a metastudy found the increased risk is 1.25 GBS cases per million doses. The Adenovirus-vectored vaccines (e.g., AstraZeneca, Johnson & Johnson) show an increased risk of GBS, estimated at 3.93 cases per million doses, and the mRNA vaccines from Pfizer and Moderna have, at the moment, a said associated risk estimated at 0.69 cases per million doses1. The GBS risk was 2.6 times increased with the first dose and mortality for GBS after vaccination was 0.10 per million doses and 4.6 per GBS cases.
Another study identified 15,377 (8072 males [52.49%]) reports of vaccine-associated GBS among 22,616 reports of all drugs-cause GBS from 1978 to 2023 from 170 countries, also noting that the “cumulative reports of vaccine-associated GBS have been increasing steadily over time, with a notable surge observed since the commencement of COVID-19 vaccines administration in 2020. Most vaccines showed significant associations with GBS such as Ad5-vectored COVID-19 vaccines (ROR, 14.88; IC, 3.66), COVID-19 mRNA vaccines (ROR, 9.66; IC, 2.84), and inactivated whole-virus COVID-19 vaccines (ROR, 3,29; IC 1.69). Influenza vaccines showed the highest association (ROR, 77.91; IC 5.98). Regarding age-and sex-specific risks, the association remained similar regardless of sex, with an increased association observed with advancing age. The mean time to onset was 5.5 days. Amid the COVID-19 pandemic, the reports of GBS surged in response to widespread COVID-19 vaccination.”
One study conclude: “These findings suggest both the absence of safety concern for GBS with mRNA-based COVID-19 vaccines and an increased risk with adenovirus-vectored COVID-19 vaccines.”
Despite the identified risk, it is the FDA’s risk-benefit assesment that “the benefits of vaccination with Abrysvo and Arexvy continue to outweigh their risks”. The advice is that those with a history of GBS should discuss with their healthcare provider about the risks and benefits of specific vaccines.
The FDA Safety Communication of January 7, 2025
CDC Approval
University of Minnesota
Respiratory-Therapy
Managed Healthcare Executive
Guillain–Barré syndrome and COVID-19 vaccination: a systematic review and meta-analysis (Pub Med)
Vaccines and Guillain-Barré syndrome (Pub Med)
Global burden of vaccine-associated Guillain-Barré syndrome over 170 countries from 1967 to 2023
Guillain-Barré Syndrome Associated with COVID-19 Vaccines: A Perspective From Spontaneous Report Data
Guillain-Barré syndrome in association with COVID-19 vaccination: a systematic review
