I’m an infectious diseases epidemiologist who have led research groups across Europe & Africa and served on several international expert panels. My research focuses on understanding the transmission dynamics of bacterial/viral infections and designing novel strategies to control disease. My work has influenced policy in African countries. I have experience conducting innovative clinical trials, pioneering the use of intrapartum azithromycin to improve maternal and neonatal health outcomes, a trial now replicated by several research institutions. In recent years, my portfolio has expanded to assess the impact of the COVID-19 pandemic in West Africa and strengthen regional preparedness for future pandemics. I’m a dedicated mentor, committed to nurturing the next generation of global health leaders. I am also an advocate for gender equality, promoting inclusivity within the scientific community.
Research interests
My research focuses on preventing deaths caused by bacteria and viruses in Africa, prioritizing innovative approaches to mitigate health inequities. Leveraging my expertise in clinical trials’ design, I led a multi-country study showing that intrapartum azithromycin prevents maternal and neonatal infections. My team continues to explore broader implications of the intervention to guide wider implementation across Africa. I have led research assessing the impact of vaccines tackling on respiratory infections disease burden and antimicrobial resistance. My work has revealed critical differences in pneumococcal vaccine effectiveness in high-transmission African settings compared to high-income countries, shaping regional vaccine policy. Demonstrating leadership, my team responded rapidly to the COVID-19 pandemic, pioneering SARS-CoV-2 research in West Africa. We applied epidemiological and genomic strategies to document transmission dynamics and impact on mortality.
Selected publications
– Grey-Johnson M, et al., Roca A & Usuf E 2025,COVID-19 testing acceptance among symptomatic individuals screened for a randomized clinical trial in The Gambia‘, Vaccine, 127608.
– Sanyang B, et al., Roca A* & de Silva TI. 2025, ‘Effect of intrapartum azithromycin on early childhood gut mycobiota development: post hoc analysis of a double-blind randomized trial‘, Nature communications, 16 – 1 – 7356.
*contributed equally
Selected research activities
In 2025, I served as Chair of the AMR Independent Advisory Panel for the REACH Network, providing expert review of AMR data. The panel ensures surveillance data is integrated into decision-making in Sub-Saharan Africa to strengthen health outcomes through evidence-based strategies.
I also presented the results of our PregnAnZI-2 trial in an intrapartum azithromycin round table at FIGO (International Federation of Gynecology and Obstetrics). Our findings directly informed newly published WHO guidelines on intrapartum antibiotic use for vaginal births to reduce preventable maternal and newborn deaths.
A key scientific output this year was a publication led by one of my PhD students, now Dr Bakary Sanyang, showing that intrapartum azithromycin has minimal impact on the neonatal fungal microbiome and providing critical evidence supporting intervention safety.
This year marked a major milestone for our group: four of my PhD students passed their vivas, reflecting our strong mentoring environment. I am confident they will continue to contribute to impactful global health research.
I also organised the Maternal and Neonatal Stakeholders Meeting in The Gambia, bringing together 50 stakeholders from Gambian and European institutions. The meeting identified key policy gaps and explored opportunities to strengthen national maternal and newborn health services. It also marked the start of a series of clinical papers to be published as a Journal Supplement in early 2026 based on the rich PregnAnZI-2 dataset—one of the largest neonatal cohorts in West Africa.