Immunosuppressed persons (ISPs) are at high-risk for hospitalization if infected with respiratory syncytial virus (RSV) and the new RSV vaccines were not studied in ISPs even though they often do not respond to vaccines as well as healthy people. By measuring and characterizing the antibody response to RSV vaccines in ISPs we will understand the factors associated with a poor response to RSV vaccines and be able to improve vaccine design and recommendations in this high-risk group of people.