His two greatest achievements are cited as overseeing the eradication of smallpox,[2] and the attempted control of Australia's rabbit plague through the introduction of Myxoma virus.

[3] The Australian Academy of Science awards annually the prestigious Fenner Medal for distinguished research in biology by a scientist under 40 years of age.

[6] In May 1937, Fenner was a member of an Adelaide University anthropological expedition to Nepabunna Mission in the northern Flinders Ranges in South Australia led by J.B. Cleland, which also included Charles P. Mountford as ethnologist and photographer, as well as botanist Thomas Harvey Johnston and others.

[8][9] Following his war-time service he was recruited by Frank Macfarlane Burnet to work at the Walter and Eliza Hall Institute of Medical Research in Melbourne.

In 1949, he received a fellowship to study at the Rockefeller Institute for Medical Research in New York City, he worked on mycobacterium Bairnsdale bacillus, which causes Buruli ulcer, the third most important mycobacterial disease worldwide after tuberculosis and leprosy.

[citation needed] Returning to Australia in 1949, he was appointed professor of microbiology at the new John Curtin School of Medical Research at the Australian National University, Canberra.

Before its eradication, smallpox was one of the world's most virulent viruses, responsible for millions of deaths, and leaving many of the victims who survived with disfiguring scars for life.

[16] On 30 March 1958, Victoria Fenner shot and killed herself, as part of a supposed suicide pact with another child, Catherine Webb, who provided the rifle and bullets.

The coronial inquiry heard she had been passing through a period of extreme mental and spiritual disturbance and the coroner declared her death a suicide.