Examining the immune response of participants receiving Modified Vaccinia Ankara vaccine in Africa (MpoxVax AFRIVAC): a prospective cohort study – protocol
Joanne Byrne, Winters Muttamba, Alain Balola Ntaboba, Bariki Mtafya, Mudarshiru Bbuye, Arthur Kalyebi Watelo, Elena Alvarez Barco, Ayleen Mufudza, Barnabas Bakamutumaho, Eoin R Feeney, Andrew Ekii Obuku, Nyanda Elias Ntinginya, Patrick D M C Katoto, Wilber Sabiiti, Bruce Kirenga, Patrick W G MallonIntroduction
Mpox remains an ongoing global health concern, driven by an ongoing clade I outbreak in Central Africa, which has caused substantial morbidity and mortality. Despite deployment of the Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine, data on the durability of vaccine-induced immune responses remain limited, particularly in African populations, women and people with HIV, highlighting the need for context-specific immunogenicity data.
Methods and analysis
Mpox-Vax AFRIVAC is a prospective, multicentre observational cohort study conducted in Uganda, Tanzania and the Democratic Republic of the Congo (DRC). Adults eligible for MVA-BN vaccination for mpox prevention or who received a first dose within 28 days prior to enrolment are followed for 48 weeks. Serial blood samples are collected to quantify binding antibody responses and assess their durability over time. The primary outcomes are mean geometric MVA-BN-specific antibody titres at week 48 and the rate of antibody decay from week 6 to week 48. Secondary outcomes include antibody kinetics at intermediate time points, factors associated with immune responses, breakthrough infection and vaccine safety. Analyses will use descriptive and longitudinal statistical methods to evaluate immune response trajectories and associated host factors, including HIV status, age and sex.
Ethics and dissemination
The study is conducted in accordance with the Declaration of Helsinki, registered at the Pan African Clinical Trials Registry (PACTR202601855406764) and publications will be in accordance with the recommendations of the International Committee of Medical Journal Editors. The study has received ethical approvals in Uganda, DRC and Tanzania. Approval for Uganda has been obtained from Uganda Virus Research Institute Research and Ethics Committee (GC/127/1062) and Uganda National Council for Science and Technology (HS5575ES), for DRC from the Institutional Committee of Health ethics (UCB/CIES/PB/001/2025) and for Tanzania from the National Institute for Medical Research (NIMR/HQ/R.8a/Vol.IX/5187).
Trial registration number
PACTR202601855406764.