[4][5] In an effort to understand rheumatoid arthritis and multiple sclerosis, Fish has investigated the immune responses that underpin autoimmunity.
[6] In 2003 Fish led investigations antivirals that could into the severe acute respiratory syndrome (SARS) outbreak in Toronto.
[8] The success of these clinical trials prompted her group to examine the use of IFN-α as a treatment for emerging infectious diseases, including Influenza A virus subtype H1N1.
[6][10] In 2017 she led a clinical trial where she observed that patients treated with IFN-α had better outcomes than those receiving conventional treatment.
[11][12] After this study, the IFN-α developed by Fish was used to treat patients with Middle East Respiratory Syndrome (MERS).
[8] Fish worked with the World Health Organization to establish the effectiveness of ebola vaccines and therapeutic interventions.
[8] In April 2020 Fish investigated interferons as a treatment for coronavirus disease, and participated as an advisor to the COVID-19 Therapeutics Task Force convened by Innovation, Science and Economic Development Canada.