🦠microbiology review

Influenza B virus

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Influenza B virus is one of the primary types of viruses responsible for causing seasonal flu in humans. Unlike Influenza A, it primarily affects humans and is less likely to cause pandemics.

5 Must Know Facts For Your Next Test

  1. It has two main lineages: B/Victoria and B/Yamagata.
  2. Influenza B virus mutates more slowly compared to Influenza A virus.
  3. Symptoms typically include fever, cough, sore throat, body aches, and fatigue.
  4. It can lead to severe respiratory infections especially in children and the elderly.
  5. The annual flu vaccine usually includes strains of Influenza B.

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