From Ebola to COVID-19, zoonotic diseases, viruses that cross from animal to humans, are increasing in frequency. Why is this happening and what can be done to stop this dangerous transfer? Steve Paikin talks to Dr. Samira Mubareka, microbiologist and infectious diseases physician at Sunnybrook Hosital, who was part of the team that recently isolated SARS-CoV-2, the agent that caused COVID-19.