How do outbreaks sometimes finish?

There are several ways that an outbreak can come to an end. The Severe Acute Respiratory Syndrome (SARS) outbreak was controlled through close coordination between public health officials and clinicians who were able to diagnose cases, isolate infected patients, trace their contacts, and implement strong infection control policies. An outbreak can also end once the virus has infected most of the people who are susceptible to it, or once there is a safe and effective vaccine available.