What is flu?
Flu or influenza is a contagious (spreads from person to person) viral illness that affects the respiratory tract (the nose, throat and lungs). Flu infections are more common during the fall and winter. Although flu cases peak between December and February, flu activity may be seen as late as May. According to the Center for Disease Control and Prevention (CDC), getting a flu vaccine shot during 2020-2021 is more important than ever because of the ongoing COVID-19 pandemic. Remember that the seasonal flu vaccine does not protect you against the COVID-19 pandemic. The two types of flu are distinct and respond to separate vaccines.
During flu season, you must have heard the terms “type A” and “type B” flu infections. These depict two of the different types of influenza viruses. Flu viruses are of four main types: A, B, C and D. Human influenza type A and B viruses are mainly responsible for the “flu season,” or seasonal influenza epidemics almost every winter in the United States.
- Type A influenza: This is the cause of most flu cases. It is the only influenza virus causing flu pandemics (a large number of flu cases affecting most of the world). It is further divided into various subtypes based on the two surface proteins (hemagglutinin or H and neuraminidase or N) such as H1N1 (swine flu) and H3N2.
- Type B influenza: This generally causes seasonal flu infections and only affects humans. It does not change as rapidly in its genetic and antigenic characteristics as type A influenza.
- Type C influenza: This causes mild illness and is not involved in causing flu epidemics.
- Type D influenza: This mainly infects cattle and is not known to cause illness in humans.
Which flu is worse, A or B?
Type A influenza is generally considered worse than type B influenza. This is because the symptoms are often more severe in type A influenza than in type B influenza. Type A influenza is more common than type B influenza. Researchers suggest that most adults have considerable immunity against type B influenza. Thus, type B influenza is less common in adults than type A influenza and when it occurs, it is less severe as well. Children, however, may develop severe disease following type B influenza. It is noteworthy that just like type A influenza, type B influenza can cause serious and life-threatening disease in some people. Moreover, both infections can pass from person to person.
What are the signs and symptoms of type B influenza?
The signs and symptoms of type A and B influenza are similar. The symptoms of type A influenza are generally more severe than those of type B influenza. The signs and symptoms of influenza include
- Fever (generally sudden in onset) or feeling feverish in the absence of a high body temperature
- Sore throat
- Loss of appetite
- Muscle pains
- Runny or stuffy nose
- Vomiting (more common in children than in adults)
- Diarrhea (more common in children than in adults)
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