Transcript for Health officials warn that this flu season could be severe
As Americans bundle up to face the cold, another seasonal foe already doing damage. Health officials warning this flu season could be severe, with the flu shot not much help. Here's Maggie Rulli. Reporter: Tonight, a new flu warning. Doctors fearing the virus is hitting faster, with cases already spiking in some regions. The CDC reporting Louisiana, Mississippi, and South Carolina already showing high levels of flu activity compared to zero states this time last year. Another concern, the national institutes of health warning this season's vaccine may only be 10% effective against the severe strain of the flu. A grim reality for the family of Alani Murrieta. Never in a million years would we have thought we would have lost her like this. Reporter: Her family says the 20-year-old mother of two was perfectly healthy until she got the flu last week. Influenza is not at all anything like a bad cold, people are hospitalized, lose weeks of work, and die of complications. Reporter: The CDC is reporting hundreds of new flu cases each week. Officials fear the numbers will keep increasing through the holidays. Tom? Maggie, thank you. There's still much more ahead on "World news tonight"
This transcript has been automatically generated and may not be 100% accurate.