She was born in
Gibraltar to Louis O'Garra and Theresa O'Garra in 1954. From 1977 to 1980, O'Garra studied at
Chelsea College, University of London, and graduated with a B.Sc. (first class honours) in microbiology and biochemistry. At the
National Institute for Medical Research (NIMR), she earned her Ph.D. in microbiology, staying on there for a four-year
post-doctorate in
immunology. In 1987, O'Garra left England for Palo Alto, California, to work for the DNAX Research Institute, where by 2000 she had become a principal staff scientist in the department of
immunobiology. In 2001, she became the head of the Division of Immunoregulation at the
Medical Research Council NIMR in London. Since 2015, she has been an associate research director and group leader at the
Francis Crick Institute, the successor institute to the NIMR. ==Research==