What is the safest Respiratory Syncytial Virus (RSV) vaccine available in the United States?

Safety Profile of RSV Vaccines Available in the United States

All three FDA-approved RSV vaccines (Arexvy, Abrysvo, and mResvia) have comparable safety profiles, with no single vaccine demonstrating clear superiority in terms of safety for adults aged ≥60 years. 1, 2

Overview of Available RSV Vaccines

The United States currently has three FDA-approved RSV vaccines for adults:

• Arexvy (GSK): Protein subunit vaccine 1
• Abrysvo (Pfizer): Protein subunit vaccine 1
• mResvia (Moderna): mRNA vaccine (most recently approved - May 31,2024) 1

Safety Considerations for Each Vaccine

Arexvy (GSK)

• Post-licensure monitoring has identified a potential increased risk of Guillain-Barré syndrome (GBS) 2
• FDA has required inclusion of GBS warning in prescribing information 2
• Otherwise demonstrates acceptable safety profile in clinical trials 1

Abrysvo (Pfizer)

• Similar to Arexvy, post-licensure data suggests potential increased risk of GBS 2
• FDA has required inclusion of GBS warning in prescribing information 2
• When used in pregnant women (32-36 weeks gestation), there were observations of more preterm births compared to placebo, though differences were not statistically significant 1
• Also observed were more hypertensive disorders of pregnancy compared to placebo recipients, though again differences were not statistically significant 1

mResvia (Moderna)

• As the most recently approved vaccine (May 2024), has less post-licensure safety data available 1
• In clinical trials, severe reactogenicity events were more common among mResvia recipients than placebo recipients 1
• No specific warnings for GBS have been identified at this time 2

ACIP Recommendations

• The Advisory Committee on Immunization Practices (ACIP) does not express preference for any particular RSV vaccine 1
• ACIP recommends a single dose of any FDA-approved RSV vaccine for:
  • All adults aged ≥75 years 1
  • Adults aged 60-74 years who are at increased risk for severe RSV disease 1
• Adults who have previously received any RSV vaccine should not receive another dose 1

Considerations for Special Populations

• For pregnant women specifically, only Abrysvo is approved for use during pregnancy (32-36 weeks gestation) to prevent RSV in infants 1
• For immunocompromised patients and frail elderly, additional surveillance and evaluation are necessary as these populations were underrepresented in clinical trials 2

Real-World Effectiveness Data

• Recent data from the Veterans Health Administration showed high vaccine effectiveness (78.1%) in preventing RSV infection among adults ≥60 years 3
• Vaccine effectiveness was 80.3% against RSV-associated hospitalization 3
• This real-world data supports the current recommendations for vaccination in older adults 3

Conclusion

When considering safety alone, no single RSV vaccine demonstrates clear superiority over the others for adults aged ≥60 years. All three FDA-approved vaccines (Arexvy, Abrysvo, and mResvia) have comparable safety profiles with different potential concerns. The choice should be based on availability, individual risk factors, and discussion with a healthcare provider. For pregnant women specifically, Abrysvo is the only approved option for maternal immunization to protect infants.