(CNN) - Last flu season was the deadliest in four decades.
The US Centers for Disease Control and Prevention says 80,000 Americans died of flu and its complications last winter.
In previous seasons, flu-related deaths have ranged from about 12,000 to about 56,000.
The 2017-2018 season was also marked by high severity across all age groups the first season where the CDC found that to be the case.
Severity is based on flu activity, hospitalizations, and deaths from pneumonia or influenza
Overall, the effectiveness of the seasonal flu vaccine for last season was estimated to be 40-percent.
Health Centers for Disease Control and Prevention 2017-2018 influenza