This year's flu season, which began earlier than usual, is shaping up to be one of the worst in recent years, officials have said.
By the numbers, here's a look at the flu:
3: Types of seasonal influenza viruses: A, B and C.
62%: Effectiveness rate of this year's flu vaccine.
47: States reporting widespread flu activity during the week ending January 5.
554,313: Hospital visits for symptoms of "influenza-like illness" during the week ending January 5.
111 million: Workdays lost because of sick days relating to the flu, reported in 2011.
$4.6 billion: Direct cost of flu season in the United States, including doctors' visits, hospitalizations and prescriptions.
Less than 6 months: Age of a baby too young to receive a flu shot.
20: Number of pediatric deaths reported as of January 5.
48: Number of hours the flu virus can live on surfaces.
3.2: Percentage of people who told Gallup in December that they had the flu "yesterday." This is up from 2.8% the same time a year earlier.
20 seconds: Length of time you should scrub your hands when you wash, to remove germs and bacteria adequately.
60%: Recommended amount of alcohol necessary in hand sanitizers to kill germs.
5 feet: Possible radiated distance of the spray from a sneeze. Yuck!
Up to 65: Percent increase in facial tissue sales in the wintertime.