Once the flu virus enters a cell it can turn that cell into a viral factory, making many more copies of the flu virus and causing illness. [2:54]

Learn how Type B Influenza virus has genetic drift, whereas Type A Influenza virus has genetic drift AND shift. Rishi is a pediatric infectious disease physician and works at Khan Academy. [7:44]

Many people choose to avoid the flu vaccine each year. Review five popular excuses, and how they relate to common misunderstandings about the flu. Rishi is a pediatric infectious disease physician and works at Khan Academy. [7:57]

Learn about the three types of influenza virus (Type A, Type B, and Type C) and what makes them different from one another. Rishi is a pediatric infectious disease physician and works at Khan Academy. [8:16]

Learn about how the flu vaccine is made every year in this video, Explore how the World Health Organization chooses what strains the of the flu should vrus should be included to protect most people. [9:17]

The flu virus has the unique ability to change in two different ways, causing genetic shift and drift. Learn exactly how these two mechanisms differ from one another. [4:55]

Just because you're feeling better doesn't mean you can't get other people sick. Turns out, you can spread the flu for longer than you might think. [2:58]

When sick people search the Web for remedies or tweet about their symptoms, they're sending an early warning signal about disease outbreaks. Now scientists and public health officials are listening in. [2:44]

Learn how antiviral drugs help people fight diseases like the flu. [13:49]

A video over viewing the two types of flu vaccines that are used. Learn the differences between LAIV (live, weakened) and TIV (dead) vaccines, and when each is appropriate to be used. [7:48]

A video reviewing over popular excuses for people avoiding the flu vaccine. [7:58]

Learn about the three types of influenza virus (Type A, Type B, and Type C) and what makes them differ from one another. Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical...

Learn when testing for influenza makes sense, and the most common test that is used. Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical advice and are for informational...

Understand the differences between TIV (dead virus) and LAIV (alive, but weakened virus) and who should get which one. Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical...

Until recently, the only way to detect a flu epidemic was by accumulating information submitted by doctors about patient visits. This process took about two weeks to reach the CDC - much too long to be effective. In an effort to improve...

Why does the flu affect different people differently? We'll hear about new research into what makes the virus work.

We'll get the latest on the outbreak of Type A, H1N1 influenza. What are researchers learning from studying the virus -- and how are doctors and other health professionals dealing with its spread?

Researchers say they may have found an Achilles' heel in the structure of the influenza virus.

They both bring wintertime suffering, but how similar is the common cold to influenza, scientifically speaking?

Should seniors get the flu vaccine? A new report is discussed in this audio recording showing evidence that the flu shot works for seniors is lacking. [22:10]

What are some strategies people can use to protect themselves from getting the flu? An expert offers advice. Aired Jan. 18, 2013 [17:35 min]

This year's flu season is off to a later start than any other year on record, according to the CDC.