Flu Vaccine - Benefits and Side Effects

Influenza is a respiratory infection caused by a virus called influenza, which causes outbreaks almost every year at the time of winter. The colder the winter is more common often influenza outbreaks.

Flu vaccine
Flu vaccine

Influenza is a benign disease in the vast majority of cases, having a mortality rate below 1%. However, being highly contagious, it is capable of infecting millions of people in a relatively short time, causing a rate of 1% represents, in absolute numbers, a large number of victims. Therefore, vaccination against influenza viruses has become an important public health measure in recent years.

In this article we explain the flu vaccine, addressing the most frequently asked questions on the subject.

What is the flu vaccine?

The flu vaccine is made from killed virus. It contains only some specific proteins of the influenza virus, called antigens, which are capable of stimulating the immune system to produce antibodies.

The influenza virus is famous for its high frequency of mutation, which compromises the ability of the immune system to create antibodies that are effective in the long run. You can have a cold today and create highly effective antibodies against the influenza virus. The problem is that in the coming years, there is a good chance of circulating virus has to be different from that contaminated him. Antibodies that you created will now be no longer effective, or are only partially effective against the new mutant strain.

The great epidemics of influenza that arise from time to time as the pandemic H1N1 (swine flu), 2009, occur every time the influenza virus undergoes as relevant mutations that make it virtually a new virus in the eyes of the majority of the immune system of population. The virus is so different from those Influenzas people have had throughout their lives, virtually no one has immunity against it. Millions of people get sick around the silent and the flu becomes headline newspapers for weeks. However, after the period of crisis, the population creates the necessary antibodies, and the strain of influenza that both startled becomes a little feared and unable to infect large crowds microbe (until a new mutation appears and start the cycle all over again) .

As a result of this characteristic of influenza, there are several different strains of the virus circulating around the world. So for a vaccine to be effective, it needs to be effective against more than one type of Influenza and often need to be updated in order to always be active against the latest mutations.

Therefore, new vaccines are produced annually in order to cover the Influenza virus strains that circulated most recently. Worldwide for research so that we know exactly what the strains that are circulating with greater intensity, both the North and in the South. These surveys are guiding the composition of the vaccine each year.

Currently, the production of vaccines takes on average six months from the selection of the circulating strains until the final product available for distribution. As vaccination campaigns are made in the fall, the vaccine is usually prepared in the previous months, usually in the spring. Thus, except for cases of sudden intensive mutations, there are rarely mismatches between the strains covered by the vaccine and the strains circulating in the population.

The choice must fall by the fact that the immune system needs about 1 month to fully develop an immunity against strains present in the vaccine. As the peak of flu activity occurs in winter, the vaccinated population will have enough time to be prepared against the virus.

It is worth remarking that the flu shot does not contain all known strains of influenza, only those that are likely to be more active in the coming winter. For 2015, ANVISA, with support from the World Health Organization, has already shown that the flu vaccine in Brazil have activity against the following variations of influenza:
  • Influenza A / California.
  • Influenza A / Switzerland.
  • Influenza B / Phuket.
  • Influenza B / Brisbane.

As the vaccine is made with virus specific proteins, it may also be effective against various other strains of influenza. For example, the composition of the 2015 vaccine will also be effective against strains of Influenza A / South Australia, A / Norway, A / Stockholm and 2009 H1N1 because they all possess antigens that are present in the vaccine.

Who should get the flu vaccine?

Anyone over 6 months old can receive a flu shot. However, there are certain groups that should receive priority in vaccination campaigns because they are at greatest risk of developing complications. In the case of influenza, the goal of vaccination campaigns not eliminate the movement of the virus but rather to reduce the incidence of complications and therefore the number of deaths.

Therefore, the target audience of these campaigns are health professionals, individuals over 60, children between six months and five years old, pregnant during the influenza outbreak period, indigenous people, prisoners, patients with chronic diseases and transplant.

If you are not part of the target group of the campaign and still want to be immunized against flu, so no problem there. The vaccine has practically no contraindications. See your doctor or health care health center and inquire.

Contraindications to influenza vaccine

Virtually all people over 6 months of age can be vaccinated against flu. In some countries there is a flu vaccine made with live attenuated virus. This vaccine has its own contraindications that are not covered in this text. We will stick only to the vaccine made with killed virus, which is commonly used vaccine in vaccination campaigns.

The main contraindication to influenza vaccination is the egg allergy. As the preparation of the vaccine uses chicken eggs, people allergic reactions can develop. If you are allergic to eggs, do not take the flu vaccine without medical advice.

There should also be some caution about people who have had Guillain-Barré syndrome (SBG). In fact, the risk of developing this disease after influenza vaccine is extremely low, about 1 case per 1 million doses. This means that the risk of having a complication of influenza is much higher that the risk of developing Guillain-Barre after vaccination. If you have had GBS and is part of the influenza risk group, talk to your doctor about the risks and benefits of the vaccine.

Individuals with acute febrile illness should not be vaccinated until they are fully recovered.

Side effects of flu vaccine

The influenza vaccine composed of killed virus are generally well tolerated, with the most common side effect of pain and inflammation at the injection site. In clinical studies, serious adverse events were very rare.

Other adverse effects may occur, but is uncommon and of short duration typically include: headache, fever, nausea, cough, irritation to the eyes and muscle pain. There are reports of fainting among teens, but these seem to be more related to fear of needle than the vaccine itself.

Frequently asked questions

1. You can catch the flu from the vaccine?

No. The vaccine is made with virus fragments. There is no chance of someone getting the flu due to vaccination.

2. The flu vaccine also prevents colds?

No, despite having similar symptoms, influenza and the common cold are different infections caused by different viruses.

3. Even vaccinated can get the flu?

Yes, the vaccine covers the main strains, but does not cover all. The success rate is about 70 to 90%. However, most people have been referred to with the same flu vaccination in fact have cooled frames. As most people can not distinguish the flu from a cold, this confusion is common.

4. Pregnant women can receive the flu vaccine?

Yes, not only can as they should.

5. immunosuppressed people, such as people with HIV or transplant can be vaccinated.

Yes, not only can as they should.

6. Can I get the vaccine at any time of the year?

It can even, but as the peak efficacy of the vaccine occurs in the first three months, the ideal is to take it just before the winter, which is the time that influenza outbreaks usually arise. To take a long time before the outbreak of vaccine may make its effectiveness is not the one intended.

7. If I travel to the northern hemisphere, Brazil's vaccine is effective?

As part because the selected strains are not the same. In 2015, for example, the 4 selected strains in Brazilian vaccine, only two are present in American and European vaccine. On the other hand, if the trip is to another country in the southern hemisphere, the coverage is total, because the composition of the vaccine is usually the same.

8. The flu vaccine interfere with any other vaccine?

No influenza vaccine can be administered the same day or next to other vaccines.

9. How long does the flu vaccine to take effect?

At least 2 weeks are required for the antibodies induced by the vaccine can be produced.

10. We really need to get vaccinated every year?

Yes, vaccination must be reinforced every year. The vaccine that you took in 2014 will not protect you during the winter flu outbreak 2015.

11. I'm not part of the risk group. Still need to vaccinate me?

Need not have to, because the risk of influenza complications in your case is very low. However, as the rate of adverse effects of the vaccine is very low, you will be more secure if it is vaccinated. In the assessment of pros and cons, the pros come out winners by a wide margin.

12. Do you know someone who has been vaccinated?

Yes, me. By being a health professional, I take the flu shot every year since 2010, without ever having any problems.

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