Researchers have reported that individuals aged 60 and older with compromised immune systems, such as organ transplant recipients on immunosuppressive medications, exhibit reduced responses to respiratory syncytial virus (RSV) vaccines compared to their peers with normal immune function. The study, published in the Journal of the American Medical Association (JAMA), builds on previous research examining vaccine responses in immunocompromised individuals, including those for SARS-CoV-2, the virus causing COVID-19.
RSV is a highly contagious virus that primarily affects the respiratory system. While it commonly causes mild infections in infants and young children, it can lead to severe respiratory illnesses such as pneumonia in older adults and immunocompromised individuals. Vaccines targeting RSV have been developed to address this public health challenge, yet their efficacy appears diminished in certain populations.
The study followed 38 immunocompromised participants aged 64 to 72 years who received either RSVPreF3-AS01 (Arexvy) or RSVpreF (Abrysvo) vaccines. Most participants were solid organ transplant recipients (82%) and were taking two or more immunosuppressive medications (74%). The vaccines work by inducing an immune response to the pre-fusion form of the RSV F protein, which is crucial for viral entry into cells. This response is measured by the production of neutralizing antibodies against RSV, which help prevent infections.
The analysis revealed that antibody responses among immunocompromised individuals were significantly lower than those observed in clinical trials of healthy individuals of the same age group. Responses varied widely, with some participants showing strong immunity while others had minimal antibody production.
To explore potential reasons for this variability, the study examined the role of vaccine composition. The Arexvy vaccine contains an adjuvant, a chemical that enhances the immune response, whereas the Abrysvo vaccine does not. Participants who received Arexvy demonstrated higher levels of RSV-neutralizing antibodies compared to those who received Abrysvo. This suggests that adjuvants may play an important role in improving vaccine efficacy for immunocompromised individuals.
Although the immune response to these vaccines is reduced in people with weakened immunity, the study does not imply that RSV vaccines are ineffective in this group. Vaccination remains a critical tool for reducing the severity of RSV infections, and current guidelines from the U.S. Centers for Disease Control and Prevention (CDC) recommend that individuals aged 75 and older, as well as those aged 60 and older at high risk of RSV infection, receive a single dose of an RSV vaccine. These guidelines include immunocompromised individuals, who remain at elevated risk for severe respiratory illnesses.
Boyarsky et al. evaluated the immune response to Pfizer-BioNTech and Moderna COVID-19 vaccines in solid organ transplant recipients (SOTRs), revealing significantly weaker antibody responses compared to healthy individuals, particularly among those receiving immunosuppressive therapy. This highlights the challenges faced by immunocompromised populations in achieving protective immunity following vaccination.
The findings highlight the challenges in achieving robust vaccine responses in immunocompromised populations, underscoring the need for ongoing research to optimize vaccine timing and selection for better protection. Larger, more comprehensive studies are necessary to confirm these results and refine vaccine strategies for this vulnerable group. This work adds to the growing evidence supporting the need for tailored vaccine approaches for immunocompromised individuals as new pathogens and vaccines emerge.
References
- Karaba AH, Hage C, Sengsouk I, Balasubramanian P, Segev DL, Tobian AAAR, et al. Antibody Response to Respiratory Syncytial Virus Vaccination in Immunocompromised Persons. JAMA [Internet]. 2024 Dec 30 [cited 2025 Jan 2]; Available from: https://doi.org/10.1001/jama.2024.25395
- Boyarsky BJ, Werbel WA, Avery RK, Tobian AAR, Massie AB, Segev DL, et al. Immunogenicity of a Single Dose of SARS-CoV-2 Messenger RNA Vaccine in Solid Organ Transplant Recipients. JAMA. 2021 May 4;325(17):1784–6.