An estimated 80,000 Americans died of flu and its complications last winter, according to the US Centers for Disease Control and Prevention. This means it was the deadliest season in more than four decades -- since 1976, the date of the first published paper reporting total seasonal flu deaths, said CDC Spokeswoman Kristen Nordlund.
In previous seasons, flu-related deaths have ranged from a low of about 12,000 during the 2011-2012 season to a high of about 56,000 during the 2012-2013.
Overall, the United States experienced one of the most severe flu seasons in recent decades. Severity is based on flu activity, hospitalizations, and deaths from pneumonia or influenza, explained Nordlund. She added, "across the board, last year was definitely bad."
The season began with an increase of illness in November; high activity occurred during January and February, and then illness continued through the end of March.
"The thing that was most notable about last year was how high in terms of activity things were," said Nordlund. She explained that last season, unlike previous seasons, flu did not strike one region of the country and then move across the land. "There were three consecutive weeks when the entire continental US was affected by flu at a very high level," she said.
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.
Overall, the effectiveness of the seasonal flu vaccine for last season was estimated to be 40%. This means the flu vaccine reduced a person's risk of having to seek medical care by 40%, the CDC found.