It is currently circulating at the same time as influenza A.
The flu epidemic is still not weakening. The latter began in mid-December 2024 and is still at a “high level of intensity” according to Public Health France, so much so that the joint vaccination campaign against influenza and Covid-19 which was to end on January 31, 2025 is extended until February 28, 2025. The agency also observes a “co-circulation of the 3 influenza viruses A (H1N1), A (H3N2) and B/Victoria”. If we often hear about influenza A, what about influenza B?
The definition of influenza B
There are 4 types of influenza viruses: A,B,C and D. This infectious disease, very contagious, is caused by viruses called “influenza viruses”. It is the influenza A and B viruses that cause the famous seasonal epidemics, “but only type A viruses have been responsible for pandemics to date”explain Public health France. There is no difference in contagion between different types of viruses. Influenza A viruses are themselves classified into subtypes or “strains”, depending on the characteristics of proteins present on their surface. For example, the 2 typical sub-layers of influenza A which circulate in the human population are H1N1 influenza and H3N2 influenza.
B viruses differ slightly because they are not classified into subtypes, but can be subdivided into lineages. “They belong to either the B/Yamataga line or the B/Victoria line”according to theWHO. The three Influenzaviruses A, B and C infect humans. Influenza A also circulates in aquatic birds (including ducks), chickens, pigs or horses, “while Influenzavirus B is specific to humans”explains theInserm. “Type B viruses only cause localized epidemics, especially in small communities of elderly people.specifiesPasteur Institute.
What are the symptoms of influenza B?
The symptoms of influenza A and influenza B are similar. They usually begin about 2 days after infection and cause a sudden onset of fever, cough (usually dry), headache, muscle and joint pain, sore throat or even a runny nose.
Treatments to treat influenza B
Most people who get the flu recover on their own. It is recommended to stay home and rest, drink plenty of water and consult a doctor if symptoms worsen. According to Public Health France, treatment for the flu is primarily directed against the symptoms and consists of the prescription of medication against fever (paracetamol for example), pain, cough or even a blocked nose.
“Vaccination is the best means of protection against influenza. It must be carried out at least two weeks before the start of the influenza epidemic (as winter approaches). Vaccination must be renewed every year”recommends Public Health France. Health insurance covers vaccination for adults aged 65 and over, people with certain long-term illnesses, people with asthma or chronic pulmonary disease, pregnant women, immunocompromised people, people obese and people staying in a health establishment.