The Flu: All you need to know

The flu is a contagious respiratory disease. Caused by a virus, it is transmitted very easily through the air (coughing and sneezing), hands or through contaminated objects. To prevent its spread we must take some basic hygiene measures (hand washing, sneezing into the inner elbow or in a handkerchief, airing the house regularly, …).

There are several types of influenza viruses

As stated by the World Health Organization (WHO), there are four types of seasonal influenza virus: A, B, C and D.

– Types A and B are the cause of seasonal epidemics, hence they are included in vaccines.

-C viruses are detected less frequently and also cause only minor infections.

– Type D viruses do not affect humans, only cattle.

Is it necessary to get vaccinated every year?

The flu virus has a high mutation capacity and the types of flu viruses that circulate are changing from year to year. Thus, our defenses cannot recognize and protect us, which can cause disease again every new winter season.

For this reason, every year  a different vaccine is made, adapted to the changes that the virus has experienced and to those strains that are circulating. WHO, after studying the reports of epidemiological surveillance centers spread throughout the world, decides each year what will be the composition of vaccines to protect us in the most effective way.

What vaccines to choose?

In Spain, both trivalent influenza vaccines and tetravalent vaccines and only injectable preparations are available.

The difference between the trivalent flu vaccine and the tetravalent vaccine lies in the number of influenza virus strains included in it.

-The trivalent vaccine contains three strains every year: two of type A and one of type B.

-The tetravalent vaccine includes four: two of type A and two of type B, of which one is of the B / Victoria lineage and another of the B / Yamagata.

To an extent it is difficult to know in advance which lineage the B strains circulating during the season will belong to, but the tetravalent vaccine allows to increase the level of protection. In addition, tetravalent vaccines have shown in studies to be as safe as trivalent vaccines. This means that they can be used, both one and the other, in the same situations.

What vaccine is recommended to use?

Given the level of scientific evidence available, the AEP Vaccine Advisory Committee advises, preferably and whenever available, tetravalent influenza vaccines. Of course, if you do not have access to it, the recommendation is to administer trivalent vaccines.

Who should get vaccinated?

Children from 6 months to 4 years (59 months);
People 50 years of age and older (because they are more likely to suffer from chronic conditions that put them at high risk of presenting a serious case of influenza disease).
People with chronic lung diseases (such as asthma), heart disease (except hypertension), kidney, liver, hematological, neurological or metabolic disorders (including diabetes mellitus);
People immunosuppressed for any cause (including immunosuppression caused by medications or the human immunodeficiency virus);
Women who are pregnant or will be during the flu season and women who gave birth until two weeks ago;
Persons 6 months to 18 years of age who receive medications containing aspirin or salicylates and who are at risk of having Reye’s syndrome after influenza virus infection;
Residents of nursing homes and other chronic care facilities;
Native Americans / Alaska Natives
people with morbid obesity (body mass index [BMI] of 40 or higher);
health care staff;
People in contact with low mobility people at home and caregivers of children under 5 and adults over 50. Special emphasis on people who are in contact with children under 6 months or with people with certain medical conditions that put them at increased risk of serious complications from influenza.

 Special consideration about egg allergy

People allergic to eggs can receive any approved influenza vaccine recommended and according to their age (IIV, RIV4 or LAIV4). People with a clinical history of severe egg allergy (those who have had other symptoms besides hives after being exposed to eggs) should receive the influenza vaccine in a medical setting and under the supervision of a health care provider who is able to recognize and manage severe allergic reactions.

Bérénice Ibarra Ottino