ABC, the Flu Virus Comes in Three

The flu (influenza) is a lung infection caused by a number of viruses that belong to the influenza family. There are three main types of influenza virus: A, B & C. Read on to find out how each type might affect you.

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Understanding the flu virus

Not all flu viruses are the same, and even the same flu virus can affect each person differently. Some types of flu can infect animals as well as people while other types only infect people. Influenza viruses constantly change or mutate on their own, or by crossing with another strain, usually from birds or pigs.

The three main types of flu viruses are A, B and C. Types A and B are the viruses most responsible for flu outbreaks each flu season. Type C viruses cause milder illness and don’t cause epidemics.

The flu shot is a yearly injection that protects you from types A and B.


Flu virus type A

The influenza virus type A can infect both animals and humans. It is the most serious of flu viruses causing widespread outbreaks worldwide (pandemics).

Type A viruses are classified into subtypes based on 2 types of proteins found on the surface of the virus, HA proteins (1 through 18) and NA proteins (1 through 11). An example of a type A influenza subtype is H1N1, also known swine flu. Three HA subtypes (H1, H2 and H3) and two NA subtypes (N1 and N2) are known to cause the most widespread human disease.

For this flu season, experts believe that two main influenza A subtypes (H1N1 and H3N2) will cause the most infections.

Type A flu viruses change/mutate constantly, creating new strains of the virus and the need to develop new vaccines each flu season.


Flu virus type B

Influenza virus type B is only found in people. And while it is usually milder than type A, it can sometimes be very serious. Type B tends to occur more sporadically than type A, and may cause a major flu outbreak in one place rather than pandemics or an epidemic.
Influenza virus type B is not divided in to subtypes like Type A, but is broken down into strains. There are 2 strains/lineages that have been recognized since the early 80s – the Victoria lineage and the Yamagata lineage. Type B viruses change/mutate more slowly than type A viruses, creating variants in each lineage.
Most flu shots protect against 2 type A strains and 1 type B lineage, however, newer flu vaccines protect from 2 type A strains and both type B lineages.


Flu virus type C

Influenza virus type C is the mildest and rarest of the influenza viruses. Symptoms of type C infection tend to be milder than types A and B.  This type of virus does not cause epidemics or pandemics and is slower to change or mutate than both types A and B.
Influenza type C doesn’t pose a significant threat to public health, as outbreaks tend to be minor and in localized areas.
While there is currently no vaccine to help prevent Type C influenza, most people who get it will only have minor symptoms.


Important information

The Pharmacist at Walmart is always available to talk to you about how to prevent and treat the flu. If you want to know how to protect your family from the flu... Just ask!

This information should not be used as a substitute for the medical care and advice of your doctor. There may be variations in treatment that your physician may recommend based on individual facts and circumstances. If you have questions about your symptoms, ask the Pharmacist at Walmart for more information, and/or contact your doctor.

The pharmacist at Walmart does not endorse or recommend any sponsor or their products or services.
Any representation, performance claim, warranty or guarantee in any materials herein is the sole responsibility of the sponsor that has prepared such materials and is not independently verified by Walmart.
This article is intended as general information. Always be sure to read and follow the label(s)/instruction(s) that accompany your product(s). Walmart will not be responsible for any injury or damage caused by this activity.



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