Majdi is an infectious disease doctor and scientist proudly raised in Grimsby. He trained in medicine at UCL and the London School of Hygiene and Tropical Medicine before working at the World Health Organization on ways to improve health for young people around the world. He was a Frank Knox fellow in public health at Harvard University and continued his clinical and academic work in Boston, USA. He co-founded YLabs, a non-profit based in San Francisco and Rwanda combining design with public health to develop youth-friendly health care and OpenBiome, a non-profit biotech spun out of MIT developing new medicines using gut bacteria.