Flu vaccine: when to take it, when to avoid it (and other questions)

The flu vaccine protects against the different types of the Influenza virus responsible for the development of influenza. However, as this virus undergoes many mutations over time, it becomes increasingly resistant and, therefore, the vaccine needs to be redone every year to protect vaccinated people against new virus mutations.

The vaccine is usually given through an injection into the arm and helps the body develop immunity against the flu, preventing the onset of flu-related complications such as pneumonia or heart problems, in addition to hospitalization and death. For this, the vaccine exposes the person to a small dose of the inactivated flu virus, which is already enough to "train" the defense system to defend itself in case it ever comes into contact with a live virus.

The price of the flu vaccine varies between R $ 100 to R $ 200 in private clinics, but it can also be done free of charge at SUS by people who belong to the flu risk groups.

1. Which risk groups should get the vaccine?

The vaccine is indicated for people at higher risk of getting the flu virus, such as:

• Children between 6 months and 6 years old incomplete (5 years and 11 months); Adults aged 55 to 59 years; Elderly over 60 years; Pregnant women; Women in postpartum up to 45 days; Health professionals; Teachers; Indigenous population; People with compromised immune system, such as HIV or cancer; People with chronic disease, such as diabetes, bronchitis or asthma; Trisomy patients, such as Down syndrome; Adolescents living in socio-educational institutions.

In addition, prisoners and other persons deprived of their liberty must also be vaccinated, especially due to the conditions of their location, which facilitates the transmission of disease.

2. Does the flu vaccine protect against H1N1?

The flu vaccine protects against different groups of the flu virus, including H1N1. In the case of vaccines administered free by SUS, they protect against 3 types of the virus: influenza A (H1N1), A (H3N2) and Influenza type B, being known as trivalent.

The vaccine that can be purchased and administered in private clinics is usually tetravalent, also protecting against another type of Influenza B virus.

3. Where can the vaccine be administered?

The flu vaccine offered by SUS to groups at risk is usually administered at health centers during vaccination campaigns. However, this vaccine can also be made by those who are not part of the risk group, in private clinics, after payment of the vaccine.

4. Do I have to get the vaccine every year?

The flu vaccine has a duration that can vary between 6 to 12 months and, therefore, it must be administered every year, especially during the autumn. In addition, as influenza viruses undergo rapid mutations, the new vaccine serves to ensure that the body is protected against the new types that have emerged over the year.

Once administered, the flu vaccine starts to take effect in 2 to 4 weeks and, therefore, is not able to prevent a flu that is already developing.

5. Is it possible to get the flu vaccine?

Ideally, the vaccine should be given up to 4 weeks before any flu symptoms appear. However, if the person already has the flu, it is advisable to wait for the symptoms to disappear before having the vaccination, to avoid that the natural flu symptoms are confused with a reaction to the vaccine, for example.

Vaccination will protect the body against another possible infection with the flu virus.

6. What are the reactions of the flu vaccine?

Some side effects that may arise after applying the vaccine include the development of cold symptoms, such as chills or runny nose. In addition, a reaction can also develop at the site of the bite such as pain, swelling and redness. In this case, it is recommended to apply an ice pebble on the spot for a few minutes throughout the day, in order to reduce swelling.

In more rare cases, headache, tiredness, muscle pain, weakness or unusual sensation in the arms and legs, high fever and abnormal bleeding may still occur.

7. Who should not get the vaccine?

This vaccine is contraindicated for people with bleeding, guillain-barré syndrome, blood clotting problems such as hemophilia or bruises that easily appear, neurological disorder or brain disease.

In addition, it should also not be applied to people with allergies to eggs or latex, a weakened immune system, as in the case of cancer treatments or if you are taking anticoagulant drugs, as well as during pregnancy and lactation.

8. Can pregnant women get the flu vaccine?

During pregnancy the woman's body is more vulnerable to infections and, therefore, there are great chances of getting the flu. Thus, the pregnant woman is part of the risk groups for influenza and, therefore, should have the vaccination free of charge at SUS health posts.