Is the risk of Guillain-Barré Syndrome (GBS) lower with the Moderna (mRNA-1345) Respiratory Syncytial Virus (RSV) vaccine compared to other RSV vaccines?

Moderna RSV Vaccine May Have Lower Risk of Guillain-Barré Syndrome Compared to Protein Subunit RSV Vaccines

Based on current evidence, the Moderna mRNA-1345 RSV vaccine appears to have a lower risk of Guillain-Barré Syndrome (GBS) compared to the protein subunit RSV vaccines (GSK's Arexvy and Pfizer's Abrysvo). 1

Evidence for GBS Risk Among Different RSV Vaccines

Protein Subunit Vaccines (GSK Arexvy and Pfizer Abrysvo)

• FDA self-controlled case series analysis among Medicare beneficiaries showed adjusted incidence rate ratios for GBS of 2.30 (95% CI = 0.39-13.72) for GSK's Arexvy and 4.48 (95% CI = 0.88-22.90) for Pfizer's Abrysvo when comparing days 1-42 post-vaccination to days 43-90 1
• While these findings did not provide conclusive evidence of elevated GBS risk, they could not rule out an increased risk associated with these protein subunit vaccines 1
• The Advisory Committee on Immunization Practices (ACIP) specifically noted that "postlicensure safety surveillance suggests a potential increased risk for GBS after protein subunit RSV vaccination" 1

Moderna mRNA-1345 Vaccine

• ACIP explicitly stated that "no GBS signal was observed after Moderna mResvia vaccination in RCTs" 1
• However, it's important to note that postlicensure safety surveillance for the Moderna vaccine has yet to occur, limiting our complete understanding of its safety profile 1

Clinical Decision-Making Algorithm

1. For patients ≥75 years: Consider any FDA-approved RSV vaccine, with potential preference for Moderna mResvia if GBS risk is a specific concern 1

2. For patients 60-74 years with risk factors for severe RSV disease:

   • Consider any FDA-approved RSV vaccine 1
   • If patient has personal or family history of GBS or other neurological disorders, Moderna mResvia may be preferred 1, 2
   • Risk factors include chronic cardiovascular/lung disease, end-stage renal disease, diabetes with complications, neurologic conditions affecting airway clearance, chronic liver disease, chronic hematologic conditions, severe obesity, moderate/severe immunocompromise, or nursing home residence 1

3. For patients 60-74 years without risk factors:

   • RSV vaccination is not routinely recommended due to uncertain benefit-risk balance 1

Important Caveats and Considerations

• The benefit-risk analysis still favors vaccination for high-risk groups despite potential GBS risk - estimated RSV-associated hospitalizations, ICU admissions, and deaths preventable per million vaccine doses exceed potential vaccine-attributable GBS cases 1
• GBS risk appears to be rare overall - less than 1 case per million doses for most vaccines historically 3
• GBS has been associated with other vaccines in the past, most notably the 1976 swine influenza vaccine, but associations with most modern vaccines are primarily temporal rather than causal 3, 4
• The mRNA platform used in Moderna's RSV vaccine has shown reassuring safety data in COVID-19 vaccines, where studies found no statistically significant increase in GBS risk after mRNA vaccination 5
• Ongoing safety surveillance is critical as more data becomes available, particularly for the newer Moderna RSV vaccine 1, 2

Bottom Line

While the Moderna mRNA-1345 RSV vaccine appears to have a lower risk of GBS based on clinical trial data compared to protein subunit vaccines, all RSV vaccines are recommended equally by ACIP for appropriate age and risk groups. For patients with specific concerns about GBS, the Moderna vaccine may be preferred, though postlicensure safety data is still needed to confirm this potential advantage 1.