The respiratory syncytial virus (RSV) vaccine landscape for older adults has expanded significantly with the FDA's approval of Moderna's mRESVIA (mRNA-1345) on May 31, 2024, marking the third RSV vaccine available for adults 60 years and older. This approval follows the earlier approvals of GSK's Arexvy and Pfizer's Abrysvo in May 2023, providing healthcare providers with multiple options to protect vulnerable populations against RSV-associated lower respiratory tract disease.
Clinical Efficacy Across Three Platforms
The three vaccines have demonstrated robust efficacy in large-scale clinical trials. Moderna's mRESVIA showed 83.7% vaccine efficacy against RSV-associated lower respiratory tract disease with at least 2 signs or symptoms in the ConquerRSV trial, which enrolled approximately 37,000 participants from 22 countries. The vaccine also demonstrated 82.4% efficacy against disease with at least 3 signs or symptoms and 68.4% efficacy against RSV-associated acute respiratory disease.
GSK's Arexvy, the first FDA-approved RSV vaccine for adults, demonstrated 82.6% effectiveness in preventing lower respiratory tract disease during the first RSV season in the pivotal AReSVi-006 trial involving 24,966 participants. However, effectiveness declined to 56.1% in the second season. The vaccine contains a prefusion F glycoprotein (RSVPreF3) and an adjuvant called AS01E to boost immune response.
Pfizer's Abrysvo showed the highest initial efficacy at 88.9% during the first RSV season in the RENOIR trial with approximately 36,000 participants. This protection remained strong during the partial second season at 78.6% efficacy. Unlike the other vaccines, Abrysvo is bivalent, targeting both RSV A and B strains using two prefusion F proteins.
Safety Profiles and Adverse Events
All three vaccines demonstrated acceptable safety profiles in their respective trials. For mRESVIA, individuals experienced more local adverse reactions (58.7% vs 16.2% in placebo) and systemic reactions (47.7% vs 32.9%). Common adverse effects across all vaccines included injection-site reactions such as pain, redness and swelling, along with fatigue, myalgia and headache.
Arexvy was more reactogenic than placebo, but most adverse events were transient with mild to moderate severity. There were similar incidences of serious adverse events and potential immune-mediated diseases in both treatment arms. For Abrysvo, 9% of vaccine recipients and 8.5% of placebo recipients reported adverse events occurring up to one month after injection.
Expanded Indications and Recommendations
The vaccine landscape continues to evolve with expanded approvals. On June 7, 2024, the FDA approved Arexvy for use in adults 50 to 59 years of age with increased risk. Additionally, Abrysvo has dual approval for active immunization of pregnant women between 24 and 36 weeks gestation to prevent RSV-associated lower respiratory tract disease in their infants from birth through 6 months of age.
The CDC recommends that adults 60 years or older should receive a single dose of an RSV vaccine through shared clinical decision-making between healthcare providers and patients. Adults at higher risk for severe RSV include those in nursing homes and individuals with chronic health conditions, frailty, or other factors that increase their risk of respiratory illness.
Pharmacist Role in Implementation
With their accessibility and vaccine expertise, pharmacists are positioned to play a crucial role in RSV vaccination efforts. Nine in ten Americans live within five miles of a pharmacy, and half live within one mile. Pharmacies often maintain longer hours and more days per week than primary care providers, with patients visiting pharmacists twelve times more often than physicians during the year.
Beyond administering vaccines, pharmacists can answer questions about RSV vaccines, address patient concerns, and ensure safe vaccination processes. This accessibility becomes particularly important for reaching older adults who may face barriers to accessing traditional healthcare settings.
Clinical Impact and Disease Burden
RSV represents a significant health burden, particularly for adults 65 years and older, with higher risks for individuals with medical frailty and long-term care facility residents. The virus also poses elevated risks for immunocompromised individuals, including transplant recipients and those on immunosuppressive medications, as well as individuals with chronic obstructive pulmonary disease, asthma, or heart failure.
The availability of three distinct RSV vaccines provides healthcare providers with options to tailor vaccination strategies based on patient characteristics and clinical considerations. The vaccines can be co-administered with COVID-19 and influenza vaccines in older adults, though there is currently insufficient evidence to determine revaccination needs.
