Osier's expertise is in malaria, where she believes we can "Make Malaria History" through vaccination. She previously led two core teams of over 25 scientists in Kenya and Germany, that focused on creating highly effective malaria vaccines through vaccine candidate discovery, identifying immune correlates of protection and unravelling important mechanisms underlying antibody-dependent protection. They designed an innovative protein microarray KILchip©, a first of its kind in Africa. Through the SMART partnership, they assembled 10,000 samples from across Africa to probe their chip, the largest study of this nature. They created a paradigm shift in the understanding of the mechanisms that underpin protective immunity to malaria. Osier is past president of the International Union of Immunological Societies (> 60,000 members globally)—the first African and only second woman in this role. She has won prestigious prizes including: Royal Society Pfizer; Sofja Kovalevskaja; and UK Medical Research Council - UK Department for International Development African Research Leader. She was honored with the prestigious British Society of Immunology Honorary Lifetime Membership Award (2022).