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Cold, Flu, & Cough Health Center

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Types of Flu

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How Is Type C Flu Virus Different From the Others?

Influenza C viruses are also found in people. They are, however, milder than either type A or B. People generally do not become very ill from the influenza type C viruses. Type C flu viruses do not cause epidemics.

Do Different Types of Flu Viruses Hit the Population Each Year?

Different strains of the flu virus mutate over time and replace the older strains of the virus. This is why it's important to get a flu shot each year to ensure that your body develops immunity to the most recent strains of the virus.

As determined by the CDC, the viruses in a flu shot and FluMistvaccine can change each year based on international surveillance and scientists' estimations about which types and strains of the flu will be most potent that year. Previously, all flu vaccines protected against three influenza viruses: one Influenza A (H3N2) virus, one Influenza A (H1N1) virus, and one Influenza B virus. Today, FluMist and some traditional flu shots cover up to four strains: two Influenza A viruses and two Influenza B viruses.

About two weeks after getting a flu shot or FluMist, antibodies that provide protection against the flu viruses develop in your body.

What Is the Bird Flu?

The avian influenza virus causes bird flu. Birds can be infected by influenza A viruses and all of its subtypes. Birds are not capable of carrying either type B or C influenza viruses.

There are three main subtypes of avian flu, including H5, H7, and H9. The subtypes H5 and H7 are the most deadly, while the H9 subtype is less dangerous.

Which Type of Bird Flu Is in the News?

Health care professionals had been very vocal about the strain of avian influenza known as H5N1.

The reason H5N1 has caused so much alarm is its ability to pass from wild birds to poultry and then on to people. While wild birds are commonly immune to the devastating and possibly deadly effects of H5N1, the virus has killed more than half of the people infected with it. The risk of avian flu is generally low in most people because the virus does not typically infect humans. Infections have occurred as a result of contact with infected birds. Spread of this infection from human to human has been reported to be extremely rare.

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