2023-12-13 22:17:35
Every winter, influenza viruses A and B strike France. The symptoms and complications are generally the same. However, these two types of flu, which continue to mutate, require the vaccine to be updated every year.
Influenza B: few differences with type A influenza
It exists 3 flu viruses that affect human beings: virus influenzae de type A, B et C. These RNA viruses belong to the family of orthomixoviridae.
THE virus A et B are both responsible for influenza epidemics encountered each year in France (the type C virus causes sporadic cases.).
It should be noted that influenza A infects species other than humans, while influenza B is almost specific to humans (even if the disease is sometimes encountered in seals).
Similar symptoms and management
The nature of the symptoms of influenza A and B are similar. The same goes for their care. However, in practice, the intensity and risks of complications (particularly in vulnerable people) would be less in the case of influenza B. In addition, Health Insurance notes that type A influenza is more difficult to control because its structure can be altered. change significantly and radically quickly.
The same vaccine response
Theflu vaccine is effective once morest both types A and B.
“Nevertheless, the vaccine must constantly adapt to mutations in circulating viruses. Indeed, these two viruses contain two types of surface proteins, hemagglutinin (HA) and neuraminidase (NA), which correspond to external antigens. surface proteins constantly mutate over time,” explains Dr. Jean Tafazzoli, general practitioner.
Therefore, each epidemic episode is unique. For example, from the end of November 2022 to the end of March 2023, the influenza epidemic experienced two successive waves, due to type A(H3N2) then B/Victoria viruses. The vaccination campaign provided for specific prevention.
Influenza B, no more contagious
Influenza, whether type A, B or C, is a very contagious disease and is always transmitted in the same way by secretions from the nose and bronchi as well as by the saliva.
- Influenza is transmitted by contact direct of person to person by the sneezingthe cough and the unwashed hands.
- It is also possible to catch the disease indirectly via of objects or contaminated food.
Influenza B, responsible for winter epidemics
According to the Health Insurance website, type B influenza is the most common. She is partly responsible for winter epidemics (also linked to the influenza A virus) which affects between 2 and 8 million people in France.
As a reminder, influenza epidemics are noted by Public Health France which conducts surveillance from the beginning of October to mid-April of the following year in these weekly bulletins.
Type B viruses have evolved since 1980 in 2 lineages. These viruses present different antigens and which are represented by the B/Yamagata and B/Victoria strains. However, the Yamagata strain has apparently disappeared since the health crisis of 2020 (perhaps due to very effective health measures). Nevertheless, the Victoria and Yamagata lines are systematically targeted by the vaccination campaign each year.
Symptoms: is influenza B “less serious”?
The symptoms of influenza A and influenza B are similar. Some scientific sources report a lesser severity of influenza B compared to type A (source 2). However, other studies demonstrate that the intensity of symptoms is the same in both types of flu (source 1).
Influenza B appears suddenly following an incubation period of 48 hours on average. The usual symptoms are:
- a high fever(around 39°C) accompanied by chills and of muscle aches ;
- a fatigue intense (asthenia), a feeling of despondency with loss of appetite;
- of the headache (headache);
- a dry cough: “Let’s not forget that the flu is a virus which targets the cells of the tissues of the respiratory tract. It enters these cells and multiplies there. The new viruses emerging from the infected cells cause their death, and will infect neighboring cells and so on”, explains Doctor Jean Tafazzoli, general practitioner.
Sometimes other signs can be added: sore throat, runny nose, etc.
A person who has the flu is contagious to others, up to five days following the first symptoms begin in adults, or even seven days in children.
Be careful, a flu syndrome can also be a sign of covid-19: the best is to take a test to detect the SARS-Cov-2 virus in order to rule out a diagnosis of covid.
Influenza B complications: who is at risk?
Whether type A or type B, the flu is responsible for sometimes serious complications every year. She is the cause of 4000 to 6000 deaths every year (source 3).
Chez elderly, immunocompromised or chronically ill patients (diabetes, cystic fibrosis, renal failure, COPD, etc.), the risks are multiple: extensive lung damageworsening of their general condition, pneumonia, bacterial superinfection…
Chez the pregnant woman, lung damage linked to influenza can sometimes require hospitalization. It is sometimes the origin of miscarriages or of premature births.
Chez infants (especially before six months), hospitalization is usually necessary.
Annual influenza vaccination is therefore necessary for these vulnerable people (apart from infants who cannot receive this vaccine).
Prevention: how to avoid influenza B?
Just like influenza A, influenza B can be avoided by adopting barrier measures. Vaccination is recommended for people at risk of complications.
The application of barrier gestures
To avoid transmitting or catching bronchitis during the winter season, it may be recommended to:
- wear a disposable or washable surgical mask when it is recommended;
- ventilate each room 10 minutes every hour;
- wash your hands regularly with soap and water or use a hydro-alcoholic solution;
- greet without shaking hands and avoid hugs;
- cough or sneeze into your elbow or in a handkerchief;
- blow your nose in a single-use tissue then throw it away.
“These actions apply equally to covid, to the flu and to all winter infections. They are ultimately the first protection once morest epidemics of viral diseases that are sometimes fatal for vulnerable people,” underlines Doctor Jean Tafazzoli.
A constantly updated vaccine
THE seasonal flu vaccine strains is constantly updated as changes occur. It protects once morest both types of influenza A and B.
This vaccine is recommended for people at risk of developing a serious form of influenza and for other populations to provide protection (for example, to relatives of a fragile person). In 2023, vaccination can now be offered to children aged 2 to 17 without chronic illness.
Usually, these people can benefit from100% coverage of vaccination costs by social security.
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Recommended formulation of influenza vaccines for saison 2023/2024
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How is influenza B diagnosed?
The diagnosis of influenza B can be confirmed by the doctor only through a clinical examination. It assumes the type of virus (A or B) which most often corresponds to the circulating virus causing the current epidemic.
However, for fragile and hospitalized people, tests are available:
- Rapid tests and PCR flu tests exist but they are only available in certain health establishments (laboratories, Ephad, hospitals, etc.). Additionally, rapid influenza tests are unreliable and nonspecific.
- Recently, in certain pharmacies and health establishments, there is a Flu/Covid rapid test (TROD). It is reliable and allows you to distinguish between influenza A and B. This test must be carried out by a healthcare professional (nurse, pharmacist or doctor) and the results are delivered in 15 to 30 minutes.
Treatments: how is influenza B treated?
Just like influenza A, treatment of influenza B is only symptomatic in healthy people. Rest and good hydration are sufficient for healing in 8 days. For its part, the fever generally subsides in 2 to 3 days. Of paracetamol can help relieve fever and pain. In the event of contraindications to the latter, the doctor can prescribe NSAIDs (such as ibuprofen and its derivatives) for a short period.
“Ibuprofen must absolutely be avoided in the event of an infectious disease at the risk of a potentially serious sudden worsening,” explains general practitioner Jean Tafazzoli.
The use of a antiviral medication (Oseltamivir or Zanamivir) is most often useless. It may be offered by the attending physician to particularly fragile people (people at risk of complications targeted by vaccination). Finally, antibiotics are ineffective once morest influenza which is a disease oforigine virale.
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