Adjuvanted Vaccines May Increase RSV-Neutralizing Antibody Levels in Immunocompromised Individuals, Study Finds

Older adults with weakened immune systems, such as organ transplant recipients on immunosuppressive medications, respond less robustly to respiratory syncytial virus (RSV) vaccines than their peers with normal immune function, according to a study published in JAMA.

The study, conducted by the Johns Hopkins Transplant Research Center, parallels earlier research on vaccine responses to SARS-CoV-2 in immunocompromised individuals. RSV, a contagious respiratory pathogen, poses risks to all age groups but can lead to severe illnesses, such as pneumonia, in older populations and those with compromised immunity.

“We found that on average, older adults who are immunocompromised developed fewer antibodies against RSV following vaccination as compared with the very strong responses for healthy people over age 60 seen in the clinical trials used to validate the vaccines,” said lead author Andrew Karaba, MD, PhD, assistant professor of medicine at the Johns Hopkins University School of Medicine. “Additionally, antibody levels in people who are immunocompromised were highly variable, with some study participants showing strong increases in immunity because of the vaccines while others barely responded.”

The researchers followed 38 immunocompromised adults aged 64 to 72, predominantly organ transplant recipients, who received 1 of 2 RSV vaccines: Arexvy or Abrysvo. Both vaccines target the F protein in RSV’s pre-infection form (pre-fusion F), which is crucial for neutralizing the virus. While both vaccines are effective in healthy individuals, immunocompromised participants showed variability in antibody responses, raising questions about the role of vaccine composition.

Researchers examined the impact of adjuvants included in some vaccines. Arexvy, which contains an adjuvant, led to higher levels of virus-neutralizing antibodies than Abrysvo, which does not. Senior author William Werbel, MD, PhD, suggested that this highlights the potential of adjuvanted vaccines to enhance immunity in this population. “So, adjuvant-enhanced vaccines as a means of improving immune response in people who are immunocompromised merits further investigation in larger, more comprehensive studies,” he said.

Despite weaker responses, the researchers emphasize that RSV vaccines likely still reduce disease severity in immunocompromised individuals. The Centers for Disease Control and Prevention (CDC) currently recommends RSV vaccination for those aged ≥75 years and high-risk adults aged aged ≥60 years, including those who are immunocompromised.

“As with our previous work with COVID-19 vaccines [which led to recommendation that people who are immunocompromised getting additional vaccine doses to improve protection], we look forward to additional research on RSV vaccine responses that will provide guidance for optimized timing and vaccine selection for people who are immunocompromised,” says Dr. Karaba.

References

People who are immunocompromised may not produce enough protective antibodies against RSV after vaccination. News release. EurekAlert!. Published December 30, 2024. Accessed January 9, 2025. https://www.eurekalert.org/news-releases/1069261

Karaba AH, Hage C, Sengsouk I, et al. Antibody response to respiratory syncytial virus vaccination in immunocompromised persons. JAMA. Published online December 30, 2024. doi:10.1001/jama.2024.25395