We begin with the growing concern over what could very well be the earliest and strongest outbreak of the flu in a decade. Tonight images from all over the country, patients flooding emergency rooms. Hospitals are readying for a tough fight against the flu. This er in minnesota, where they're putting up signs urging visitors to stay out of the er, out of the hospital, if you don't have the flu. The flu hitting 41 states tonight from coast to coast and growing this evening. More than 2,200 people in the hospital. 18 children have died and this season is just getting started. Dr. Ashton from our medical team standing by tonight, but first abc's john schriffen with the images from the front line against the flu. Reporter: From chicago to atlanta -- I don't want this shot. Reporter: -- To ohio. Doctors in emergency rooms are overwhelmed with a flu that seems to be spreading like wildfire. In florida, where the flu has hit hard and early, 7-month-old baby estrella is sick with a respiratory virus the doctors are seeing along with influenza. Just one of dozens of children dr. Rosenberg has been treating. It's been an epidemic, a lot of admissions from the flu, more Reporter: In illinois, doctors say they haven't seen this many cases since the swine flu outbreak in 2009. This year the flu is hitting even the strongest among us. Like 28-year-old matt head. One minute I'm a thousand degrees sweating to death, and then the next thing I'm four degrees, freezing to death, wishing I was dead. Reporter: In ohio, 863 people have been hospitalized with flu symptoms compared with 65 at this time last year. Our normal volume would be anywhere from 40 patients. We're seeing 75, 80 patients today. Reporter: Emergency rooms are going to have longer wait times for everyone. And we still have five weeks left to the end of the flu season. John schriffen leading us off. Thanks to you. I want to bring in abc's dr. Jennifer ashton. Always great to see you. Mr. And the cdc is encouraging anti-virls earlier than ever? For anyone not getting better within a couple days and recently the fda approved tamiflu for infants as young as two weeks of age. It tells you how seriously they take the risk in infants and children. Two weeks, but it's perfectly safe? You have tips for people without infants or young which were, sounds obvious but bears repeating. First thing, get your flu shot. It's not too late. There's still flu vaccines available. It does reduce the severity and the duration even if you were to get the flu. Second, keep your hands and anything your hands come in contact with, clean. Phones, keyboards. That's how the virus is transmitted. Wipe it all clean, keep your family safe. And other things to your immunity? Getting enough sleep, exercise, adequate vitamin d intake. 70% of the country is low on vitamin d. Keep it high, and it improve your chances. -- Of avoiding the flu.