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Rates of GBS were similar between Arexvy and Abrysvo, at 0.12% and 0.11% of total reported events, respectively.
Although the incidence of Guillain-Barré Syndrome (GBS) was slightly higher than anticipated, researchers say it is still rare among older adults who received vaccines against respiratory syncytial virus (RSV).1
GBS was identified as a potential concern in clinical trials of both Arexvy (GSK) and Abrysvo (Pfizer), both of which were approved by the FDA in May 2023 for the prevention of RSV lower respiratory tract disease in adults 60 years or older. Following their approval, data from V-safe and the Vaccine Adverse Event Reporting System (VAERS) showed that rates of GBS after RSV vaccination were higher than estimated expected background rates, at 4.4 and 1.8 reports per million doses of Abrysvo and Arexvy, respectively.2
GBS is a rare neurological disorder in which an individual’s immune system attacks part of their peripheral nervous system, resulting in weakness and sensation changes. Severity can vary, with some patients experiencing mild cases of brief weakness, and others experiencing nearly total paralysis. In severe cases, it can be life-threatening.3
Still, experts have emphasized that the benefits of RSV vaccination outweigh the potential risks for older adults, who are at particular risk of severe illness. The CDC and FDA have continued to monitor reports of GBS among this patient population.2
In research presented at the American Society of Health-System Pharmacists (ASHP) Midyear 2024 Clinical Meeting, investigators aimed to examine potential disparities in vaccine type, age, and sex that are associated with serious adverse events after RSV vaccination, including GBS. They utilized data from VAERS and clinical trial records and included individuals aged 60 years and older who received RSV vaccines between May 3, 2023, and December 31, 2024. Participants were categorized into age groups (60-74 years, 75 years and older) and classified by sex and vaccine type.1 Serious adverse events were defined as events involving hospitalization, death, life-threatening events, emergency department visits, disability, office visits, or GBS.1
According to the results, GSK’s RSV vaccine reported more than twice as many serious adverse events than Pfizer’s vaccine, although the majority of these were office visits. Specifically, 25.57% of adverse events categorized as serious were for Arexvy, compared with 11.42% for Abrysvo. However, rates of GBS were similar between Arexvy and Abrysvo, at 0.12% and 0.11%, respectively.1
When broken down by age group, more adverse events were reported in individuals aged 60 to 74, compared with those 75 years or older. Of the events reported, 27.51% of those defined as serious were for individuals aged 60 to 74, compared with 10.01 for individuals 75 years or older. Again, however, rates of GBS were similar between the younger and older age groups, at 0.16% and 0.09%, respectively.1
Finally, the researchers noted a higher incidence of serious adverse events in women than in men, at 24.08% of all events reported versus 15.13%. Rates of GBS were the same, however, at 0.12% for both groups.1
Based on these findings, the study authors concluded that although the incidence of GBS was higher than initially anticipated, it is a rare occurrence. They added that the estimated number of avoidable deaths and hospitalizations from RSV is far greater than the number of GBS cases for any subgroup, highlighting the importance of vaccination for everyone eligible.1
Pharmacists play a key role in RSV vaccination, not only by administering the vaccines but by educating patients about the importance of immunization. Patients may have concerns about adverse events including GBS, and providing accurate information could help reassure patients about the value of vaccines.