Influenza B viruses, often referred to as simply "the flu," are a type of virus that belong to the Orthomyxoviridae family. They are among the main culprits responsible for seasonal influenza outbreaks, particularly in humans.
Influenza B viruses are spherical in shape and possess a lipid envelope surrounding their genetic material, which is in the form of ribonucleic acid (RNA). They are classified into different strains based on variations in their surface proteins, namely hemagglutinin (HA) and neuraminidase (NA). These proteins are crucial for the virus to enter and exit host cells, as well as for evading the immune response.
Influenza B viruses primarily target the respiratory system, leading to symptoms such as fever, cough, nasal congestion, sore throat, and general fatigue. While they share some similarities with influenza A viruses in terms of symptoms, they generally cause milder disease and are less likely to result in severe epidemics or pandemics.
Like other strains of influenza, transmission of influenza B viruses occurs mainly through respiratory droplets from infected individuals, such as when they cough or sneeze. Additionally, the virus can survive on surfaces for a limited period, which allows for indirect contact transmission.
Vaccines are available to provide protection against influenza B viruses. These vaccines are typically updated annually to match the circulating strains and are recommended for people of all ages, particularly those at higher risk of complications such as young children, older adults, and individuals with underlying health conditions. Antiviral medications can also be prescribed to treat and manage influenza B infections, especially in severe cases or for individuals at high risk of complications.
