Ad26.ZEBOV Booster in HIV+ Adults Previously Vaccinated With Ad26.ZEBOV/MVA-BN-Filo (EBOVAC HIV+ Booster Study)

This is an open label study to evaluate the safety and immune response to a booster dose of Ad26.ZEBOV Ebola vaccine in HIV+ adults from Kenya and Uganda. Only participants who have received the 2-dose Ebola vaccine regimen \"Ad26.ZEBOV/MVA-BN-Filo \" in the VAC52150EBL2002 vaccine trial about 4 years ago are eligible to take part. Approximately 50 healthy HIV+ adults, aged 18 - 50 years at the time of the parent trial, will be invited. Participants will first be asked to provide consent to participate in this study. Upon receiving the booster vaccination, participants will be followed up for approximately 28 days (+/- 3 days) to collect information on side effects and provide blood samples for antibody measurement. This study is designed to provide descriptive information regarding vaccine safety and immunogenicity. There is no formal treatment comparisons and no formal testing of statistical hypothesis.