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Flu A vs Flu B: Understanding Differences and Similarities

There are four main types of influenza viruses which cause the flu. The most common of these are influenza A and B.

What is Influenza A?

Influenza A (sometimes called flu A) is the most common type of flu virus. This type of flu virus is so common partly because of its ability to rapidly mutate. Virus mutation makes it harder for the body’s immune system to fight flu A.

Influenza A can also infect animals. Some strains of influenza A have caused pandemics by passing from animals to people (such as the H1N1 swine flu), although most strains are milder.

What is Influenza B?

Influenza B (or flu B) is the second most common type of flu virus. In fact, influenza B makes up about a quarter of flu infections. The biggest difference between influenza A vs. influenza B is that influenza B does not infect animals. This makes it mutate more slowly, and it typically causes milder illness.

Influenza B is more common in children, and more prevalent later in the flu season.

Flu A vs Flu B: Causes

You get the flu when an influenza virus enters your body and infects your respiratory system.

While influenza A and B viruses are slightly different structurally, they are transmitted in the same way. Both types of flu are spread through tiny droplets that move through the air when someone coughs, sneezes, or talks. Virus-containing droplets can also land on surfaces. If you touch a surface containing an influenza virus and then touch your face, you may get the flu.

The main difference in how these viruses spread is that sometimes influenza A can spread from animals to people. Influenza B, on the other hand, only infects humans.

Influenza A vs B: Symptoms

Influenza A and B are very similar in terms of symptoms.

Symptoms of the Flu:

  • Fever (usually occurring suddenly)

  • Cough (usually dry)

  • Muscle and joint pain

  • Headache

  • Sore throat

  • Runny nose

  • Malaise and fatigue

Influenza A is most likely to be severe, but severe outcomes can happen from both types of virus.

Flu A vs Flu B: Contagiousness

Both influenza A and B are highly contagious. They can be spread from person to person at a distance of up to 6 feet away.

You can get flu A or flu B any time of the year, but these viruses are most common in the colder months. Infection with influenza A happens more frequently near the beginning of the flu season, and usually lasts for 1-2 weeks. Flu B, on the other hand, tends to be more common near the end of the flu season.

Flu A vs Flu B: Diagnosis

The flu is usually diagnosed based on your symptoms. In cases where it’s important to rule out other illnesses or identify the type of flu, influenza tests are available. A rapid influenza diagnostic test (RIDT) can screen for the flu.

Molecular assays and other types of tests can provide in-depth results, including which type of influenza you have.

Influenza A vs B: Treatment

Both influenza A and B are usually treated with self-care at home. This can include getting lots of rest and hydration, and easing symptoms with over-the-counter medications.

Influenza A is more likely to cause severe symptoms. The chance of complications and hospitalization is higher with influenza A, but is possible with both types of flu. People who are at a high risk of complications should ask a physician about flu treatment using antiviral medications at the first sign of flu-like illness.

Flu A vs Flu B: Prevention

To prevent exposure to influenza A and B, it’s important to wash your hands often and thoroughly. Clean and sanitize frequently-touched surfaces, and stay home when you’re sick.

Getting vaccinated is the best way to protect yourself and the people in your life from the flu. Flu vaccines are designed to protect against the two variants of influenza A and the two subtypes of influenza B that are predicted to be most active that season. Even if you’ve had the flu recently, a flu vaccine can help protect you from the other types of flu in circulation.

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If you have questions about the flu, WellNow Urgent Care is here to help. Talk to one of our experienced medical providers at your convenience. Start or schedule your virtual visit today.

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Information contained in this blog is for informational or educational purposes only and does not substitute professional medical advice or consultations with healthcare professionals. The content is not meant to be complete or exhaustive or to apply to any specific individual's medical condition. Always refer to the personalized information given to you by your doctor or contact us directly.