Phionah is employed at Makerere University Johns Hopkins University (MU-JHU) Research Collaboration, where she has gained tremendous experience through the ranks from medical officer, study coordinator and investigator. As a public health specialist, she has dedicated much of her career to advancing the field of HIV prevention initially through prevention of mother to child transmission (PMTCT) and currently through engaging in research aimed at availing different HIV prevention modalities among adolescents and women to promote sexual and reproductive health in sub-Saharan Africa (SSA). She worked on various multi-site National Institute of Health (NIH) supported HIV prevention and perinatal randomized clinical trials at MU-JHU. She is currently the Co-Investigator on the multi-site HIV Prevention clinical trial, the IMPAACT 2009 study, which evaluates the Pharmacokinetics, Feasibility, Acceptability, and Safety of Oral Pre-Exposure Prophylaxis (PrEP) for Primary HIV Prevention during Pregnancy and Postpartum in Adolescents and Young Women and their Infants) and a study coordinator on the MTN-042 and MTN-043 studies which evaluates oral Truvada/Dapivirine vaginal Ring in Pregnant and breastfeeding mothers and their infants.