By Stan Deresinski, MD, FACP, FIDSA
Synopsis: The antibody response to respiratory syncytial virus vaccination is significantly impaired in many severely immunocompromised individuals.
Source: Karaba AH, Hage C, Sengsouk I, et al. Antibody response to respiratory syncytial virus vaccination in immunocompromised persons. JAMA. 2025;333(5):429-432.
Karaba and colleagues prospectively enrolled immunocompromised individuals to examine the immunogenicity of respiratory syncytial virus (RSV) vaccines. Of the 139 participants, 38 submitted paired baseline and four-week postvaccination blood samples. Their median age was 66 years and 50% were female; 82% were solid organ transplant recipients and 74% were taking at least two immunosuppressive medications. Single-dose vaccination resulted in a median 4.21-fold increase in prefusion F (preF) immunoglobulin G (IgG) concentration at four weeks. The median fold increase in neutralizing antibody level (NT50) at four weeks was 6.97 (1.75-17.70), with just 22 (58%) subjects achieving high-titer neutralization (defined relative to reference serum). Failure to achieve this level was associated with receipt of mechanistic target of rapamycin (mTOR) inhibitors (e.g., sirolimus). Of the 19 participants who achieved a high neutralization antibody titer for whom the vaccine that had been received was known, 15 (79%) had received RSVA-AS01E, while four (21%) had received RSV-A/B (P = 0.02). The former GSK vaccine is adjuvanted while the latter Pfizer vaccine is not.
Commentary
The Centers for Disease Control and Prevention (CDC) updated its recommendations for RSV vaccination in mid-2024 to include, in addition to all adults aged ≥ 75 years, those aged 60-74 years who were considered to be at high risk of severe disease.1 Among those considered in the latter group to be at high risk were those with moderate or severe immune compromise, among which the CDC includes the presence of an immunocompromising condition and/or receipt of immunosuppressive therapy. This recommendation was made in the absence of published data indicating the efficacy or immunogenicity of the vaccines in such patients.
While not addressing efficacy, the study by Karaba and colleagues does provide some information regarding immunogenicity in a small cohort of patients, most of whom were solid organ transplant recipients and were receiving multiple immunosuppressive medications. In this cohort, 42% were considered to have failed to seroconvert to a high level of serum neutralizing antibody. While RSV vaccination remains indicated in patients such as the ones examined by Karaba et al, one should not be surprised if infection nonetheless occurs. Whether multiple doses could overcome this problem is unknown and, at the current time, this approach is not recommended.
Stan Deresinski, MD, FACP, FIDSA, is Clinical Professor of Medicine, Stanford University.
Reference
- Britton A, Roper LE, Kotton CN, et al. Use of respiratory syncytial virus vaccines in adults aged ≥60 years: Updated recommendations of the Advisory Committee on Immunization Practices — United States, 2024. MMWR Morb Mortal Wkly Rep. 2024;73(32):696-702.
The antibody response to respiratory syncytial virus vaccination is significantly impaired in many severely immunocompromised individuals.
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