Flu Outbreak Facts: What You Need to Know

Most people are surprised to learn that the flu is one of the nation’s most lethal diseases, killing up to 20,000 Americans a year. This flu season is shaping up to be particularly severe. Here’s what you need to know.

Question: Why is this flu season so bad?

Answer: Experts don’t know for sure, although this season’s predominant strain, the H3N2, is historically associated with severe illness. The last time H3N2 was the primary strain was the relatively lethal 2003-4 “Fujian flu” season. The current flu season started unusually early, but doctors don’t know why.

Question: Why does flu strike in the winter?

Answer: Scientists believe humidity is the main factor. When humidity levels are low, as they are in the winter, the flu virus is able to survive longer on surfaces.

Question: Why do so many people get sick if the flu vaccine is effective?

Answer: Less than half of Americans get the flu vaccine, and the flu vaccine is not a guarantee against the disease. The CDC says the shot is about 67 percent effective, and the effectiveness varies from year to year. Health officials do a better job in some years than others matching the vaccine against the predominant flu strain. This season, the CDC says the vaccine is a good match for strains that are circulating.

Question: If I get the flu shot now, how long will it take before the protection kicks in?

Answer: The lag time varies from person to person, but it generally takes about two weeks after getting the flu shot for immunity to build.

Question: How many people get the flu each year?

Answer: About 5-10 percent of the population get the flu in a given year, although last year was extremely mild, with just 2.2 percent getting the flu. Young children, elderly people, and those with existing medical problems are most at risk for getting a severe case. Anywhere from 5,000 to 20,000 Americans die of flu-related illness each year.

Question: In what states are you most likely to get the flu?

Answer: Massachusetts, New York, and Illinois have reported high rates of flu, but the disease is prevalent throughout the Midwest, East and South, with 41 states having widespread disease. Some western states, including Arizona, California, Oregon, and Washington, seem to be less affected so far.