The flu vaccine protects against different types of influenza viruses, which is responsible for the development of influenza. However, as this virus undergoes many mutations over time, it becomes increasingly resistant and, as a result, the vaccine needs to be remade each year to protect against new forms of the virus.
The vaccine is given by injection into the arm and helps the body develop influenza immunity, preventing serious complications such as pneumonia and other breathing problems, as well as hospitalization and death. To do this, the vaccine exposes the person to a small dose of the inactivated influenza virus, which is sufficient to “train” the defense system to defend themselves in case of contact with a live virus.
- The vaccine is available for free through the Single Health System (SUS) for people in risk groups.
- But can also be found in private immunization clinics.
Ideally, the flu vaccine should be given to people who are more likely to come into contact with the flu virus and develop symptoms and/or complications. Thus, the vaccine is recommended by the Ministry of Health in the following cases:
In addition, detainees and other detainees who are deprived of their liberty must also be vaccinated, in particular because of the conditions of their location, which facilitates the transmission of diseases.
The flu vaccine protects against different groups of the influenza virus, including H1N1. For free SUS vaccines, they protect against 3 types of viruses: influenza A (H1N1), A (H3N2) and influenza type B, being known as trivalents. The vaccine that can be purchased and given in private clinics is usually tetravalent and also protects against another type of influenza B virus.
In all cases, the vaccine does not protect against any type of coronavirus, including the cause of COVID-19 infection.
The flu vaccine offered by SUS to risk groups is usually given in health centers during immunization campaigns. However, this vaccine can also be manufactured by those who are not part of the risk group, in private clinics, after payment of the vaccine.
The flu vaccine lasts between 6 and 12 months and should therefore be given annually, especially in autumn. In addition, while influenza viruses undergo rapid mutations, the new vaccine is used to protect the body from new types that appear during the year.
Once administered, the flu vaccine begins to take effect in 2 to 4 weeks and therefore cannot prevent an already developing flu.
Ideally, the vaccine should be given up to 4 weeks before flu symptoms appear. However, if the person already has the flu, it is advisable to wait for the symptoms to go away before vaccination, to prevent natural flu symptoms from being confused with a reaction to the vaccine, for example.
The vaccine will protect the body from other possible influenza virus infection.
Some side effects that may occur after the vaccine is applied include the development of cold symptoms, such as chills or nasal discharge. In addition, a reaction may also develop at the site of the bite, such as pain, swelling and redness. In this case, it is recommended to apply an ice stone on site for a few minutes throughout the day to reduce swelling.
In rarer cases, headaches, fatigue, muscle aches, unusual weakness or sensation in the arms and legs, high fever and abnormal bleeding can still occur.
This vaccine is contraindicated for people with bleeding, Guillain-Barré syndrome, blood clotting problems such as hemophilia or skin that bruises easily, neurological disorder or brain disease.
In addition, it should not be applied to people allergic to egg or latex, weakened immune systems, such as cancer treatments or if you are taking anticoagulant medications, as well as during pregnancy and lactation.
During pregnancy, a woman’s body is more vulnerable to infection and, as a result, there is a high chance of getting the flu. For example, pregnant women are among the flu risk groups and should therefore be vaccinated free of charge at SUS health posts.