<unk>  is an annually recurring time period characterized by the prevalence of an outbreak of influenza <unk> . The<unk>  occurs during the cold half of the year in each hemisphere. Influenza activity can sometimes be predicted and even tracked geographically. While the beginning of major<unk>  activity in each<unk>  varies by location, in any specific location these minor epidemics usually take about three weeks to reach its pinnacle, and another 3 weeks to significantly diminish. Annually, about 3 to 5 million cases of severe illness and 290,000 to 650,000 deaths from<unk> al<unk>  occur worldwide.
Flu season
Pandemic
Influenza pandemic
Timeline of influenza
PLOS Pathogens
Bedpan
Third plague pandemic
First plague pandemic