Flu Resource Center

Influenza: How to prevent and treat a serious infection

It happens every year. The days grow shorter, the temperature drops — and the flu strikes. Influenza is so common that it's easy to dismiss this seasonal affliction as "just a virus" or "just the flu." It's true that the flu is caused by a virus and that most people recover without any therapy other than rest. But it's also true that thousands of Americans die from the flu each year, and millions are sick enough to miss work or school. Influenza is a serious infection — but it can be prevented and treated.

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Special features

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HealthMap Flu Vaccine Finder

HealthMap Vaccine Finder is a free service that allows users to search for flu vaccines based on their location. Powered by Harvard Medical School and Boston Children's Hospital.

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How a virus infects a cell

How an influenza virus infects a cell

See how a flu virus enters a healthy cell, replicates, and exits with this narrated, step-through animation.

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Herd immunity

Vaccination protects individuals from disease, but it can also benefit an entire community by protecting even those few who are not vaccinated. The phenomenon is known as herd immunity See how it works.

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Learn more about the flu virus and how to protect yourself