Flu vaccine: does it react? See the vaccination schedule

Despite being a common disease that is often easily treated, the flu can cause complications.

According to the World Health Organization, it is estimated that influenza is responsible for severely affecting 3.5 million people annually.

With the change in temperature between seasons, the disease becomes even more frequent, as some habits, such as leaving the environments less ventilated because of the cold, facilitate the transmission of the virus.

To keep yourself protected, especially in the case of high-risk groups, it is essential to receive the vaccine annually.

In the following text we explain how it helps in this protection, who should take it and we answer the main questions. Check out!

What is the flu vaccine?

The flu vaccine is an immunization to prevent different strains of the flu virus from causing the disease, being the main form of prevention.

This is a vaccination provided by SUS and private health units. In the public network, the flu vaccine is the trivalent one , which protects against 3 different subtypes of the influenza virus, 2 of which are Influenza A (H1N1 and H3N2) and one Influenza B virus.

The vaccine is aimed at priority groups, such as the elderly, children from 6 months to 5 years, people with chronic diseases and specific clinical conditions, pregnant women, health professionals, people in prison and prison professionals.

In private networks, the vaccine can be taken by anyone who wants to receive the immunization.

The main difference is that the dose available in private vaccination centers is quadrivalent , which protects against 2 subtypes of the Influenza A virus (H1N1 and H3N2) and 2 subtypes of the Influenza B virus.

It is safe and has no major complications, however, like any vaccine, it can cause mild side effects, such as pain in the area, malaise and fever .

After receiving the vaccine, the time needed for it to start taking effect is, on average, 2 to 3 weeks. Because of this time, the campaigns take place before the winter season, when the circulation of the virus is greater.

Vaccination campaign

Annually, the Ministry of Health promotes the National Vaccination Campaign against influenza, to alert risk groups about the need to receive the annual dose of the vaccine. In 2019, the 21st edition takes place.

In 2018, the campaign started on April 23 and extended until June 1, with the intention of vaccinating more than 54 million people in the priority group free of charge.

This year, the campaign is scheduled to take place from April 10 to May 31 . The national mobilization day, known as D-day, will take place on May 4.

However, in Amazonas, the campaign will start even earlier, still in the month of March. Because of the number of deaths already registered in the state, the government decreed that the situation is emergency and therefore anticipated immunization. There are already 24 confirmed deaths, with the H1N1 virus predominating in circulation.

The forecast is that around 1 million doses of the vaccine will arrive by the weekend in the state. First, the doses will be applied to children and pregnant women, then the vaccine will be used for other risk groups.

Flu vaccination: what changes from 2018 to 2019?

What changes from 2018 to 2019 is the start of immunization. This year the campaign was anticipated so that the number of deaths caused by the infection is reduced, especially by the number of victims already registered in the state of Amazonas.

The composition is also different, as disclosed by the National Health Surveillance Agency (Anvisa).

The trivalent vaccine, made available by public health services, must contain two subtypes of the Influenza A virus and one subtype of the Influenza B virus, which are:

  • A virus similar to the influenza A / Michigan / 45/2015 (H1N1) pdm09 virus;
  • A virus similar to the influenza virus A / Switzerland / 8060/2017 (H3N2);
  • A virus similar to the influenza B / Colorado / 06/2017 virus (strain B / Victoria / 2/87.

In the quadrivalent vaccine, in addition to the three mentioned above, it must also contain a virus similar to the influenza B / Phuket / 3073/2013 virus (strain B / Yamagata / 16/88).

This type of vaccine, however, is only available in private health services.

According to Anvisa, the vaccines approved with these strains are as follows:

  • Fluarix Tetra – GlaxoSmithKline Brasil Ltda;
  • Influvac – Abbott Laboratórios do Brasil Ltda;
  • Influvac Tetra – Abbott Laboratórios do Brasil Ltda;
  • Trivalent influenza vaccine (fragmented and inactivated) – Instituto Butantan;
  • Trivalent Influenza Vaccine (subunit, inactivated) – Medstar Importação e Exportação Eireli;
  • Vaxigrip – Sanofi-Aventis Farmacêutica Ltda.

In the composition of the vaccine in the year 2018, the specifications were as follows:

  • a virus similar to the influenza A / Michigan / 45/2015 (H1N1) pdm09 virus;
  • a virus similar to the influenza A / Singapore / INFIMH-16-0019 / 2016 (H3N2) virus;
  • a virus similar to the influenza B / Phuket / 3073/2013 virus;
  • a virus similar to the influenza B / Brisbane / 60/2008 virus (quadrivalent only).

Read more: What is H1N1 flu, symptoms, prevention and transmission

Campaign actions

Within the campaign, informational materials are made available at health centers and on social networks and websites of health institutions. The Ministry of Health is responsible for disclosing about the importance of the vaccine, the goals for the year and alerting risk groups.

In addition to the care provided at the health units, within the campaign there is a national mobilization D – Day .

In 2018, it took place on May 12, with 65 thousand posts spread across the country and 240 thousand health workers working to serve the population.

New WHO strategies for influenza control

One of the concerns of the World Health Organization is a possible new pandemic caused by the Influenza virus, and one of the priorities is to devise new strategies to prevent the disease in all countries.

Recently, the organization published what it intends to do, in this sense, to prevent seasonal influenza from becoming a worldwide concern.

The strategy has two main purposes. One is to build in the countries more competent plans for surveillance, control, prevention and preparation to prevent these cases.

For this to happen, countries are asked to develop a specific program to contain the transmission of the virus, such as the flu vaccination campaign in Brazil, for example.

The other objective is to develop tools to better control, treat and prevent the disease, such as investing in research on vaccines, antivirals and treatments that help to reduce the number of victims of the disease, especially within risk groups.

One of the WHO programs, present for more than 65 years, is the Global Influenza Surveillance and Response System (GISRS) – a global influenza surveillance system, formed by WHO partner health centers in countries.

What is the vaccine made of?

The flu vaccine is produced from the different strains of the flu virus, which are grown on embryonated chicken eggs, which is why the vaccines contain traces of egg proteins .

These viruses are purified and fragmented by a chemical process, in which they are inactivated.

This composition is updated annually to meet the needs of the population according to the viruses that are in circulation, considering that it undergoes constant mutations.

All of these changes go through processes verified and guided by the World Health Organization, which must approve the vaccine for application in the population.

When applied in a single dose, it is a preservative-free vaccine. But, when in the multidosis presentation, it contains a preservative derived from mercury, thimerosal.

They may also contain antibiotics (neomycin and gentamicin) and formaldehyde, compounds used in production to prevent contamination. In addition, you may have sodium chloride and water for injection.

What is the difference between the trivalent and quadrivalent vaccines?

The quadrivalent vaccine is offered in private health services and contains 2 different subtypes of the Influenza A virus (H1N1 and H3N2) and 2 subtypes of the Influenza B virus, according to those that were in circulation in the previous year. The trivalent has the same subtypes as Influenza A, but only one Influenza B virus.

The trivalent, moreover, is the version made available by public health clinics, offered free of charge to groups at risk. However, it is also a vaccine available in private clinics.

In the quadrivalent, the two subtypes of Influenza B are from the Victoria and Yamagata lineage. In the trivalent, only one subtype of these strains is present in the vaccine, being sufficient to prevent most cases of influenza that can be caused by these viruses.

This difference, of having one subtype less than the Influenza B virus, is due to the fact that this type of strain is not so common in circulation in Brazil, and is therefore not mandatory.

How does the dose schedule work?

The flu vaccine can be applied in a dose schedule, which, according to the patient’s age group, changes slightly.

Children from 6 months to 9 years old

For children in this age group, the flu vaccine is applied in two doses when it comes to the first immunization.

Between one vaccine and another, an interval of one month is necessary. Thereafter, the vaccine must be taken annually.

Adolescents, adults and the elderly

In children over the age of 9, adolescents, adults and the elderly, the flu vaccine is made in a single dose, also with the need for revaccination on an annual basis.

Who can take it?

Almost all people aged 6 months and older can receive the flu vaccine, but there are risk groups that are an immunization priority. Are they:

  • Children from 6 months to 5 years of age;
  • Pregnant and puerperal women;
  • Health professionals;
  • Indian people;
  • Teachers;
  • Elderly people aged 60 or over;
  • Prisoners and prison staff;
  • Patients with chronic diseases and specific clinical conditions.

Should I get vaccinated every year?

-Yeah . Ideally, especially for groups at risk, the flu vaccine should be taken annually.

For these groups, immunization is a priority because they have characteristics that make them more susceptible to contracting the disease or having complications because of it.

According to Karina Chiuratto, a pharmacist and professor of the Training Course in Vaccination Service in Pharmacies at IBRAS, the flu vaccine should be administered at this frequency due to the approximate time of protection it offers, which is generally 12 months.

“ In addition, a characteristic of influenza viruses is constant mutation, that is, they change their characteristics and the previous vaccine does not protect against ‘new’ mutated viruses. That is why, annually, the World Health Organization (WHO) recommends the composition of the flu vaccine based on the prevalence of strains circulating in the previous year around the world ”he explains.

The fact that the vaccine is annual also helps to reduce the number of deaths caused by the disease. In 2018, cases of influenza were more than twice as many as in the previous year, in 2017, with 3,558 patients diagnosed with the disease and 608 deaths.

Among the dead, the most affected group is the elderly, followed by people who have some cardiovascular complication or diabetes .

Thus, having a specific annual vaccination schedule for groups at risk also helps to reduce the number of deaths.

Can pregnant women get the vaccine?

Yes , they are even among the risk groups that should receive immunization as a priority.

During pregnancy, the woman’s body undergoes several changes, with the consequences of this period impairing the immune system, which becomes more fragile so that there is no rejection to the baby.

This way, you are more sensitive to suffering infections such as colds and flu, with a greater risk of complications, such as pneumonia and respiratory infections.

These infections, in addition to causing damage to women’s health, also pose risks to the baby. Therefore, the vaccine is essential for the protection of both.

Read more: Can pregnant women take acetaminophen? Know the dosage and risks

Price: how much does the flu vaccine cost?

The flu vaccine is available free of charge in public health units, serving priority groups. However, anyone over the age of 6 months who wants to be vaccinated can receive it through the private network, at an average price between R $ 80 and R $ 160 per dose.


As Karina Chiuratto explains, some people may be allergic to the components present in some vaccines, such as milk protein, egg protein, formaldehyde, gelatin and others.

“ For these people, vaccines are contraindicated. However, if the medical professional understands that the risk of the patient contracting the disease and suffering sequelae is greater than the risk of allergic reaction caused by the vaccine, the patient may be advised to get vaccinated, yes, but, in an environment that ensures their care immediate emergency, usually in a hospital setting ”explains Karina Chiuratto.

According to information from the Ministry of Health, egg allergy (food that is present in the vaccine) is a problem that affects 1.3% of children and 0.2% of adults.

That way, if the person is able to eat the food without any reaction, they probably will not have any side effects with the flu vaccine.

Anyway, it is important that each case of allergy is analyzed individually, and it is not possible to contraindicate the vaccine in a generalized way.

People who have a deficiency in the functioning of the immune system (immunosuppressed) also need to consult a doctor beforehand to assess the risk-benefit ratio of receiving the immunization.

Vaccine reactions: what are the side effects?

Like all vaccines, flu can also cause some adverse reactions. It can cause discomfort in the area, such as pain, redness, hardening of the region and temporary discomfort, similar to the onset of a cold .

These manifestations can occur between 15% and 20% of vaccinated people, but they are generally mild and last for up to 48 hours.

In rare cases, in people who are allergic to one of the components of the vaccine, mild allergic reactions, thicker tongue and swelling of the lips may occur.

The person may also experience a little passing fever, accompanied by a feeling of malaise and pain. It is a condition that affects between 1% to 2% of vaccinated people.

It is, in general, more common in the first application of the vaccine and can start from 6h to 12h after the injection, persisting for 1 to 2 days.

Therefore, in some cases, it may be recommended that the patient remain in the clinic or hospital for a few minutes after receiving the vaccine, as, in case of any allergic reaction, it is possible to receive care at the site.

Can the flu vaccine cause the flu?

No . As Karina Chiuratto explains, there is no chance that the vaccine will cause the disease, as it is not made with the live virus, therefore it is an inactivated vaccine.

However, it is known that some people can have side effects that resemble flu symptoms, such as malaise, fever, muscle pain and headache .

However, even though the vaccine is not able to cause the disease, it is possible that the immunized person catches the flu due to some factors such as time to start protection, composition of the vaccine and vaccine failure, as explained by the pharmacist.

“ The vaccine takes around 7 days to generate protection. If the patient already had the influenza virus incubated or came into contact with the virus after immunization, within that 7-day window, the vaccine applied will have no action against this virus ”.

Regarding the composition, she explains that in these cases the patient may present the flu after immunization, since the vaccines currently available protect against up to 4 strains of the influenza virus.

That is, the patient can receive the vaccine and contract the flu for having come into contact with a virus that is not part of the composition of the vaccine.

Vaccine failure, in this case, is a possibility for any immunization as none guarantees 100% protection.

Other precautions to avoid the flu

The vaccine is the main form of prevention of the flu, but there are several other precautions that can be taken to prevent the transmission of the disease.

Caring for personal hygiene and the environment can reduce risks. Here’s what to do:

Wash your hands thoroughly

Throughout the day, it is common to bring your hand to your mouth or eyes frequently. But, with this habit, we expose our organism to viruses and bacteria in which we have contact on the surfaces of objects, such as on shared computers and on public transport, for example.

Therefore, in addition to the vaccine, it is important to adopt the habit of always keeping your hands well hygienic, washing them more frequently with soap and water. When this is not possible, the use of alcohol gel can help as well.

Be careful when coughing or sneezing

Flu or not, we must be careful when talking, coughing and sneezing, so as not to spread particles of saliva and possibly some virus.

In such cases, when coughing and sneezing, people should cover their mouths with the inside of their arms or with some disposable handkerchief. It is important not to use your hand to cover your mouth, as this way, when placing your hand on surfaces, the contamination will be greater.

Do not share personal items

Cups and cutlery, for example, should not be shared, as they can facilitate the transmission of the virus between infected and uninfected people. If you live with someone who has the flu, avoid using it.

Keep rooms well ventilated

Despite being more common in cold times of the year, the flu is not caused by low temperatures, but by the increased circulation of the virus. This is mainly due to the fact that people leave the environments more closed.

So, even in the cold, always try to keep your windows open, whether at home, at work or on public transport.

Have a healthy diet

To protect ourselves from the virus, our immune system needs to be strengthened. One way to keep it that way is through food, including foods rich in vitamin C, omega-3 and zinc in the diet.

Common questions

Does the vaccine also protect against colds?

It does not protect . The flu vaccine protects only against the viruses that cause the flu, the cold being a different disease.

It is quite common for people to confuse the two diseases, but although the cold is also a disease caused by viruses and has similar symptoms, it is usually milder than the flu, which can lead the patient to hospitalization.

The cold is often caused by viruses such as rhinovirus, respiratory syncytial virus (RSV), parainfluenza virus, among others.

The duration of a cold is also shorter than that of the flu, lasting, on average, from 3 to 10 days. The flu, in addition to lasting 3 to 14 days, is caused by different viruses and has a high fever as a characteristic symptom.

Read more: What is the difference between a flu and a cold?

Can the vaccine interfere with the results of laboratory tests?

-Yeah . It is possible that the vaccine causes changes in the results of some tests, such as in laboratory tests to identify the presence of other viruses, such as HIV , hepatitis C virus and HTLV-1.

Therefore, when performing an examination, the patient who received the vaccine must inform the responsible professional.

Is the influenza vaccine different for children, adults and the elderly?

No . As the pharmacist Karina Chiuratto says, there are no differences in the types of virus strains according to the age group:

“ However, each laboratory manufacturer can determine, through its clinical studies, whether the concentration of antigens and other components will vary according to age. In this way, it is important to assess from which laboratory the vaccine will be the most suitable, since there is a variation between pediatric and adult doses ”.

That is, despite using the same viruses, the concentration may vary according to the age of the patient.

Who has a fever and / or taking antibiotics can get the vaccine?

It depends . The use of antibiotics, according to Karina, does not contraindicate the vaccine. ” As for fever, it is not recommended to apply any vaccine when the patient has a fever, the ideal is to wait for the end of the picture to be able to receive the vaccine ” explains.

Vaccination campaigns take place annually and we remind them of the importance of immunization to avoid complications.

If you are among the groups with priority to receive the vaccine or want to prevent the flu, go to a health facility to receive the vaccine. Thanks for reading!