Influenza A & B – What’s the difference? Which is more severe?

Influenza A and Influenza B are two different types of viruses that cause seasonal flu outbreaks in humans. While they share some similarities, there are also several key clinical differences between them.

Historical Impact

Influenza A viruses have been responsible for more severe pandemics throughout history. For example, the 1918 Spanish flu pandemic, caused by an H1N1 influenza A virus, resulted in tens of millions of deaths worldwide. Influenza A viruses generally have a broader geographical distribution and are responsible for most seasonal flu outbreaks. Influenza B viruses typically cause less widespread illness but can still contribute to significant morbidity and mortality, especially in vulnerable populations such as children and the elderly.

Severity of Illness

Both Influenza A and B viruses can cause similar symptoms, including fever, cough, sore throat, body aches, fatigue, and respiratory symptoms. However, historically, Influenza A viruses have been associated with more severe epidemics and pandemics compared to Influenza B viruses. While both influenza A and B viruses can cause similar symptoms, such as fever, cough, sore throat, body aches, and fatigue, influenza A infections may be associated with more severe respiratory complications, including pneumonia and acute respiratory distress syndrome (ARDS).

Vaccine Composition

Influenza vaccines typically target both Influenza A and B viruses. However, vaccine formulations may vary depending on the circulating strains. Influenza A viruses are classified based on their surface proteins, hemagglutinin (H) and neuraminidase (N), whereas Influenza B viruses are divided into two main lineages: Victoria and Yamagata. In Paddington Medical, we vaccinate patients with the quadrivalent (4 in 1) vaccine, which includes strains from both Influenza A (2 strains) and B viruses (2 strains) in seasonal flu vaccines.

Testing for Influenza A and B in Paddington Medical

Paddington Medical Clinic offers testing for both Influenza A and B simultaneously, in order to establish clear diagnosis, and hence guides effective treatment. The above picture shows Influenza B on top, Influenza A below.

In summary, while Influenza A and B viruses both cause seasonal flu, they differ in their host range, genetic variability, severity of illness, vaccine composition, and epidemiological impact. Understanding these differences is crucial for developing effective prevention and control strategies against influenza outbreaks. While influenza A is often considered more severe overall, influenza B infections can also lead to significant morbidity and mortality, particularly in children and elderly.

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To find out more about the “Frequently Asked Questions (FAQs) On Influenza Vaccination (FLU VACCINE)”, check out this comprehensive article on it.