She is a Personal Professor in the University of Witwatersrand's Department of Obstetrics and Gynaecology, co-director and co-founder of the Wits African Leadership in Vaccinology Expertise (ALIVE[3]), Honorary Professor in the Department of Clinical Research at the London School of Hygiene and Tropical Medicine and an Honorary Fellow at Cambridge University's Murray Edwards College, UK.
Rees has led national consultations at the invitation of the Ministries of Health in South Sudan, Ethiopia, Nigeria and the Democratic Republic of Congo.
Rees has served on expert structures and committees for WHO, UNAIDS, UNICEF, the Global Alliance for Vaccines and Immunisation and the Bill & Melinda Gates Foundation.
Rees has won many international and national awards for her contribution to global health and to science, specifically in 2001 receiving the Order of the British Empire[16] by Queen Elizabeth II.
She was the London School of Hygiene and Tropical Medicine's 2011 International Heath Clark lecturer awarded to an outstanding global health practitioner.
She was the first person to receive the SA Department of Science and Technology's award for the ‘Distinguished Scientist recognised for outstanding contribution to improving the quality of life of women’ (2006).