What is the effectiveness of abrysvo?

Abrysvo Effectiveness

Abrysvo demonstrates high effectiveness against RSV-associated lower respiratory tract disease, with vaccine efficacy of 82% against severe disease (≥3 symptoms) and 59% against moderate disease (≥2 symptoms) in adults ≥60 years, and over 80% efficacy in protecting infants when administered to pregnant individuals at 32-36 weeks gestation. 1

Effectiveness in Adults ≥60 Years

Primary efficacy data from the pivotal trial shows robust protection:

• Against severe RSV-LRTD (≥3 symptoms): 81.5% vaccine efficacy (95% CI 63.3-91.6) at median 16.9 months follow-up 1
• Against moderate RSV-LRTD (≥2 symptoms): 58.8% vaccine efficacy (95% CI 43.0-70.6) 1
• Sustained protection in second RSV season: 77.8% efficacy against severe disease and 55.7% against moderate disease at median 7.7 months into second season 1

Age-stratified effectiveness remains consistent across subgroups:

• Ages 60-69: 81.6% efficacy against severe disease 1
• Ages 70-79: 72.7% efficacy against severe disease 1
• High-risk patients with underlying conditions: 73.5% efficacy against severe disease 1

Strain-specific performance shows broad coverage:

• RSV-A: 80.6% efficacy against severe disease across two seasons 1
• RSV-B: 86.4% efficacy against severe disease across two seasons 1

Effectiveness in Maternal Immunization for Infant Protection

Abrysvo administered to pregnant individuals at 32-36 weeks gestation provides passive immunity to infants:

• Over 80% efficacy in preventing severe RSV-associated lower respiratory disease in infants during the first 3 months of life 2
• Efficacy slightly decreases after 6 months of age, which informed the FDA's pragmatic approval for use specifically at 32-36 weeks gestation 3
• FDA approval was granted in August 2023 for active immunization of pregnant individuals to prevent LRTD in infants from birth through 6 months of age 3, 4

Effectiveness in High-Risk Adults 18-59 Years

Immunogenicity data demonstrates non-inferior immune responses in younger high-risk adults:

• Neutralizing antibody GMTs were 1.57-fold higher for RSV-A and 1.52-fold higher for RSV-B compared to adults ≥60 years 1
• Seroresponse rates of 93% for both RSV-A and RSV-B in high-risk adults aged 18-59 with chronic conditions 1
• This population includes those with chronic pulmonary, cardiovascular, renal, hepatic, neurologic, hematologic, or metabolic disorders 1

Concomitant Administration

Abrysvo can be safely co-administered with other vaccines without compromising effectiveness:

• With seasonal influenza vaccine (FLUAD QUADRIVALENT): Non-inferiority demonstrated for both RSV and influenza antibody responses in adults ≥65 years 1
• With Tdap vaccine: Maintained immunogenicity for both vaccines when given concomitantly in adults 18-49 years 1

Clinical Context and Comparative Positioning

Abrysvo represents one of three major RSV prevention tools approved in 2023:

• Equally effective as Arexvy (GSK's RSV vaccine) for adults ≥60 years 5, 6
• Unique advantage: Only RSV vaccine approved for maternal administration to protect infants 5, 6
• Alternative infant protection strategy is nirsevimab (monoclonal antibody), which also shows high efficacy 2, 6

Common Pitfalls to Avoid

• Do not administer to pregnant individuals outside 32-36 weeks gestation window - the FDA specifically narrowed this interval to balance efficacy against potential risks 3
• Do not assume infants need both maternal vaccination AND nirsevimab - most infants require prophylaxis through either maternal RSV vaccination or nirsevimab administration, not both 5
• Do not expect equal protection throughout infant's first year - efficacy is highest in first 3 months and decreases after 6 months 2