Past Outbreaks
Swine influenza viruses can circulate among swine throughout the year, but most outbreaks occur during the late fall and winter months similar to outbreaks in humans.
While swine flu viruses do not usually infect humans, rare human infections have occurred. When this happens, these viruses are called “variant viruses.” Most commonly, human infections with variant viruses have occurred in people exposed to infected pigs (e.g., children near pigs at a fair or workers in the swine industry).
- Page last reviewed: May 19, 2017
- Page last updated: May 19, 2017
- Content source:
- Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)
- Page maintained by: Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs