Flu Vaccine Efficacy and Risks

Autumn and winter are times of the year to suffer an acute respiratory disease caused by the "Influenza" virus, which enters the body through the respiratory tract. The virus spreads very quickly through droplets from the coughs and sneezes of infected people.

Generally, the flu has a benign course and does not cause complications except in certain population groups at higher risk (the elderly or chronically ill). The most common symptoms are:

• High fever up to 40ºC
• Headache
• Throat pain
• muscle pains
• Dry cough
• Weakness and tiredness
• Watery and painful eyes
• Nasal congestion and runny nose

When does the vaccination campaign start?

At the beginning of autumn, the influenza vaccination campaigns are launched, which is when the virus begins to circulate. In the so-called risk groups, the flu can cause serious complications and even death. That is why it is recommended to include them in the annual flu vaccination campaigns. In addition, the vaccine is indicated in those groups that work in essential services for the community (health, firefighters, nursing home employees, etc.) since they are more exposed to the flu and so on.

What is the flu vaccine?

The flu vaccine is made up of killed or attenuated viruses that are administered through a injection intramuscular or intradermal. In adults only a single dose is indicated, but in children who have never been vaccinated, two doses are administered one month apart. Vaccinations are carried out in health centers, hospitals and nursing homes.

Efficacy and risks

The efficacy of the vaccine is not 100% since the flu virus strains change every year but the severity of the infection is always reduced. The vaccine uses the virus strains that have circulated the most in the previous year but may not correspond to those that circulate this year.

Another factor that modifies the efficacy of the vaccine is the age and health of the person vaccinated. According to data from the Ministry of Health, when the coincidence between circulating viruses and those in the vaccine is high, the vaccine prevents between 70 and 90% of influenza in healthy people under 65 years of age. In risk groups it is effective in preventing complications derived from the flu. It is estimated that it prevents 50 to 60% of hospitalizations and 80% of deaths derived from these complications. In these groups, although the efficacy in preventing the disease is lower (about 40%), the course of the disease will be less severe.

It is about one and with few side effects. The symptoms that may appear after injecting it are usually local (pain, inflammation, redness in the injected area) that disappears in about 48 hours. More infrequent is the appearance of a generalized picture of malaise with low-grade fever and generalized pain without consequences and that resolves spontaneously.

It should only be administered to people who may have a allergic reaction to any component of the vaccine and in children.

Flu Vaccine Recommended

• Children (older than 6 months) with chronic diseases (heart disease, cancer, rheumatic diseases, etc.), severe malnutrition, morbid obesity or absence of spleen.
• In adults, it is recommended from 65 years of age, to pregnant women at any stage of pregnancy, people who have undergone a splenectomy (removal of the spleen), chronic patients, health personnel and groups that work in essential public services and healthy adults who live in the environment of the population at risk.

In the event of any strange symptoms, MAPFRE Salud has a service for any queries you may wish to make about the flu vaccine or other health-related issues.