Flu shot


The disease, generally referred to as “flu”, represents an infection with the so-called influenza virus and is therefore also referred to as seasonal influenza infection in the medical field. It occurs mainly during the colder and wetter seasons and should not be confused with a common cold or a flu-like infection. Influenza can develop very differently in every person.
Some patients have clearly pronounced symptoms that are accompanied by a strong feeling of illness. Other patients, on the other hand, show milder symptoms that do not limit them too much. As with some other diseases, there is a vaccination to prevent the disease. Vaccination against most diseases takes place during childhood. Examples include diseases such as measles, mumps, rubella or chickenpox.

When should the flu shot take place?

The flu vaccination is recommended for all healthy people before or at the beginning of the flu season. Vaccination is therefore recommended from the end of September to the end of November. People belonging to a risk group can, however, also be vaccinated at another point in time. This is especially true for the elderly and children. Pregnant women and the sick should also be vaccinated, vaccination before the flu season is possible. For example, pregnant women should be vaccinated when they are four months pregnant. Such a vaccination recommendation regardless of the season also applies to people with a weakened immune system.

Who should be vaccinated against the flu?

The so-called Standing Vaccination Commission (STIKO) in Germany issues a number of recommendations for vaccinations. For the flu vaccination, the Standing Vaccination Commission recommends some groups of people to have a special vaccination carried out. These include above all older people over 60 years of age, pregnant women, chronically ill people who have an increased risk of a more severe course due to an infection with influenza, as well as residents of nursing homes and medical employees. These groups of people are those expressly named by the STIKO, as they are at an increased risk of a severe course of the disease and an increased incidence of possible complications of influenza.

Read more on the topic: Superinfection

A flu vaccination is also important for people who have frequent and direct contact with poultry. All other people can of course get vaccinated against flu at any time as a precautionary measure. So you are by no means excluded from vaccination. The STIKO just does not include you in the group of particularly endangered people who should definitely be vaccinated.

Read more on the subject at: Influenza vaccination - yes or no?

Duration of action of a flu shot

After a flu vaccination, the immune system makes antibodies against the special strain of flu virus that was contained in the vaccination. In principle, these antibodies stay in the body for years, but their number decreases over time. Nevertheless, the body is usually immune to the specific strains of flu for a few years. However, as the flu virus is constantly changing, the vaccination must be repeated every year. However, you will be vaccinated against the new flu strains. The time it takes to become immune to the flu viruses after vaccination is usually a few days. This is the time it takes for the immune system to form the first effective antibodies against the flu virus.


The flu, also known as influenza, is transmitted by the influenza viruses. They can be divided into A, B and C types. For humans, however, only types A and B are relevant for a disease. The most important feature of these viruses are their surface structures. The characteristic structures for these viruses are the so-called hemagglutinin (abbreviated to HA) and neuraminidase (abbreviated to NA). Hemagglutinin and neuraminidase are specific protein molecules that are on the surface of viruses. The interesting and complicated thing about these structures is that these two proteins still have a number of subgroups. It is precisely these subgroups that make the development of a vaccine more difficult.Due to a multitude of different mechanisms, the composition of the surface structures repeatedly changes. Since the antibodies that the human body forms are only directed against very specific structures, not every subgroup of the flu viruses can be prevented by a single vaccination with the flu vaccine. Therefore, the flu vaccine is updated every year to reflect the current composition of the flu virus subgroups.

What is the difference between triple and quadruple vaccination?

In the case of flu viruses, a distinction is made between different bacterial strains. These are divided into A and B stems. Often the A strains of the flu are predominant, which is why there is a so-called trivalent vaccine (triple vaccine), which is supposed to work against the two most important representatives of the A flu and a B flu virus strain. The tetravalent vaccine (quadruple vaccine), however, also contains a component that is supposed to help against another B strain. Therefore, this vaccine is of particular importance in a season in which the B flu is also common.
As a rule, however, it is difficult to predict which flu viruses will be circulating more often.
The flu strains that were addressed in the trivalent vaccine 2017/2018 are: A / Michigan / 45/2015 (H1N1), A / Hong Kong / 4801/2014 (H3N2) and B / Brisbane / 60/2008 or strains that are heavily involved are related to the three mentioned. With the tetravalent vaccine, the B / Phuket / 3073/2013 (or similar strains) is also covered.

As a rule, the triple vaccine is cheaper, which is why health insurances mainly conclude discount agreements for it. The quadruple vaccine, however, is often not covered by health insurance.

Which of the two vaccinations should I get?

Before the flu season, it is usually not possible to say whether the triple or quadruple vaccination makes more sense. It depends a lot on which flu strains are most prevalent. The trivalent vaccine is usually sufficient for normally healthy people. This covers the flu strains that are most likely to dominate the flu season. If you want to be on the safe side, you can also opt for the tetravalent vaccine, but in many cases you have to pay for the vaccine yourself and should therefore contact your health insurance company before the vaccination.

Flu vaccine

The vaccine used for the flu vaccination is usually a so-called dead vaccine. Here the pathogens are killed, which means that they are no longer able to divide. In addition to a flu vaccination, vaccination against pneumococci is also recommended for this risk group. Pneumococcal vaccination is particularly recommended for older people aged 60 and over. Pneumococci are bacteria that, among other things, can lead to pneumonia, which is dangerous for the elderly.

Does the flu shot contain aluminum?

Aluminum is contained in most vaccines and therefore also in flu shots. However, it is not there in its pure form, but it is in the flu vaccine as aluminum hydroxide. There it acts as an adjuvant, i.e. a substance that enhances the effect of the actual vaccine. So far it has been scientifically highly controversial whether aluminum in vaccines, food and deodorants is really dangerous. However, there is a very small dose in flu vaccines. This falls below the maximum permitted throughout Europe by around ten times and is thus well below the load limit.

Does the flu shot contain mercury?

In the past, mercury was widely used in vaccines. There it was used to preserve the vaccine. In addition, it should counteract the spread of germs and thus the contamination of the vaccine. This was especially necessary when the vaccine was delivered in larger bottles. In this case, several people were vaccinated with the vaccine from the same bottle, so there was a risk of contamination with other bacteria and viruses. Nowadays, flu vaccines are usually supplied in pre-packaged syringes. Such a syringe only contains the vaccine for one person. It is therefore no longer necessary to add mercury to the flu vaccine.

Side effects

Usually a vaccination against the flu virus is relatively well tolerated and therefore has few side effects. As with any vaccination, local reactions at the vaccination site can still occur.
The typical local reactions after vaccination are redness, swelling and pain around the injection site. In some cases, general symptoms such as a cold can also occur. So after a vaccination you may feel tired and limp or you may get headaches and aching limbs. However, these symptoms disappear completely after 1 to 2 days.


In addition to the typical inflammatory and immune-related side effects, diarrhea can also occur with a flu vaccination. However, this is not one of the most common side effects of the flu shot. The diarrhea is probably caused by slight changes in the hormonal balance. After the vaccination, the immune system is activated and antibodies against the vaccine begin to form. This also activates the metabolism in the body, which is why there is dysregulation of the water balance.


As with all other vaccinations, there are certain contraindications for the flu vaccination that should not be vaccinated. These include, for example, severe infections or an allergy to chicken protein or other components of the vaccine. If you have a serious infection, you should simply postpone your planned flu vaccination until you are healthy again. Since the 2014/2015 vaccination season, the flu vaccination has also been available without chicken protein, so that people with a chicken protein allergy can now also be vaccinated against the flu. Likewise, children and adolescents who suffer from severe immunodeficiency or severe asthma should not be vaccinated with the live flu vaccine, but only with the dead vaccine.

Allergy to egg white

Most flu vaccines are made from incubated hen's eggs. The vaccine therefore contains traces of chicken protein, which is why a flu vaccination is contraindicated if you have a strong allergy to chicken protein. In the case of slight allergies to egg white, a decision can be made depending on the vaccination indication. For example, it is recommended that pregnant women get vaccinated even if they have a slight allergy to egg white. In this case, the vaccination should be carried out under inpatient observation so that allergic reactions can be treated immediately.

Who can't get a flu shot?

A clear contraindication for flu vaccinations are allergies to ingredients of the vaccination. This also includes allergies to chicken protein, as the flu vaccines are usually made on a chicken protein basis. In addition, some immunosuppressed people are not vaccinated. In some extreme immunosuppressive diseases, the immune system is so badly damaged that antibodies cannot be formed even against a vaccine. For people who cannot be vaccinated, special medication is available in acute cases.


The flu vaccination is free of charge for people who are included in the above risk group by the STIKO. If other people want to be vaccinated against the flu, they may have to pay the cost of the flu vaccination themselves, which is between € 20 and € 35. Therefore, when vaccinating against the flu, it is always advisable to contact your health insurance company beforehand to find out whether it will cover the costs of the vaccination or not. In some companies, the vaccination is carried out by the company doctor and the employee pays the costs. Again, it is advisable to inquire about the possible costs of the flu vaccination before the planned vaccination in order to avoid misunderstandings.

Does the health insurance company cover the costs?

The health insurance company generally covers the costs for the flu vaccination for all people who want to be vaccinated. Health insurance also pays the costs for those privately insured. Ideally, you should contact the insurance company before the vaccination so that the costs can be reimbursed quickly. As a privately insured person, however, you usually have to bear the costs yourself. First of all, you have to buy the vaccine yourself at the pharmacy with a prescription from your doctor. Then you can submit the bill from the pharmacy and the doctor to the health insurance, which should then reimburse the sum.

Should you get vaccinated while you have a cold?

The flu vaccination is a treated subspecies of the flu virus that is usually injected into the upper arm muscle of the vaccinated person. There the ingredients should be absorbed by the body so that the immune system begins to fight them. It is therefore not advisable to have the flu vaccination while you have a cold. During a cold, the immune system is already at full capacity, so that the side effects of the flu vaccination can come into their own.
It is therefore better to wait about a week until the symptoms of the cold have gone. In principle, however, you can also be vaccinated with a cold. For example, a slightly runny nose does not have to be an obstacle to the flu vaccination.

How useful is a flu shot?

The first thing you should know is that the real flu is not the same as a flu-like infection or a normal cold. The flu is much more severe and you suddenly feel seriously ill. The real flu significantly restricts your everyday life so that you can often only lie in bed. Even a few weeks after the illness, it can happen that you still feel clearly ailing. A flu vaccination can prevent or significantly reduce this severe course. Vaccination presents components of the virus to the body's immune system so that it then forms antibodies. Antibodies are very special proteins of the body's own immune system, which are always specially formed by the body's white blood cells against a pathogen in order to combat it and render it harmless. The body's immune system produces antibodies when infected with a pathogen and when it comes into contact with a vaccine after a vaccination. This simulates a disease with the pathogen, so to speak, for the body without actually being sick.
With the flu vaccination, it is important to get vaccinated against the pathogen every year because it changes again and again. The vaccination should be given in October or November so that the body has time to build up immunity before the so-called flu wave starts. It is of course also possible to get vaccinated during the flu season. However, the optimal time is usually a little earlier. Due to the constant change in virus types, vaccination against the flu virus does not provide 100 percent protection against the disease as one is used to with other diseases such as measles, mumps or rubella. Especially in older people, the immune system is no longer as effective and strong as it is in young people. This can also be a reason why vaccination against flu does not lead to complete protection. Nevertheless, it is particularly important for older people to get a flu vaccination, as they have a weakened immune system due to old age and accompanying illnesses and therefore an infection with the flu pathogen can lead to serious complications such as pneumonia.
In connection with a vaccination, it is also important to know that the vaccination itself does not cause disease. Most vaccines that are used contain either only components of the pathogen or pathogen in a killed form. The flu viruses spread from person to person in two different ways. The air is one way of spreading. If an infected person sneezes or coughs, the finest particles get into the air, which can be inhaled by other people. The second way of transmission occurs through so-called smear infections, which can occur when shaking hands, for example. Both transmission paths are often difficult to avoid or restrict, as the viruses can reach and encounter you at any time in everyday life. Whether you decide for or against a flu shot is of course up to you. However, you should inform yourself well and check whether you belong to one of the respective risk groups identified by the STIKO. For these risk groups, an annual vaccination against the flu virus is recommended in order to prevent or reduce the risk of illness and the complications that may arise with it.


The flu vaccination is particularly recommended for people who are exposed to an increased risk of complications from an infection with the flu. This includes old and sick people, children and the immunocompromised. In these people, the flu usually lasts for a long time and can have serious consequences, such as pneumonia. Therefore, the side effects of the flu shot are harmless compared to what can happen if you get infected.
Medical staff, i.e. people who come into contact with many sick people, should also be vaccinated. Otherwise you can quickly become a distributor of the flu virus. Anyone who, as a healthy citizen, also wants to avoid the inconvenience of a flu infection should also get vaccinated.


As counter-arguments for a flu vaccination, the side effects of the vaccination are usually mentioned first. These can consist of a local inflammatory reaction with swelling, reddening, overheating and pain at the injection site. In addition, a feeling of sickness with weakness and fever can occur for a few days. Many healthy people also consider the likelihood of catching the flu without a vaccination to be comparatively low and would therefore like to avoid going to the doctor. A clear contraindication for the flu vaccination is an allergy to certain ingredients of the vaccination.

How dangerous can a flu shot be?

The dangers of a flu vaccination are usually very low. As a rule, there are maximally minor side effects that arise due to the body's immune defense against the vaccine. This includes, for example, a slight feeling of illness with tiredness, fatigue and fever. This can last for two to three days. However, these symptoms are definitely not the flu itself. After a flu vaccination, you are immune to these in most cases.
Local inflammatory reactions can also occur at the injection site itself. These are noticeable as a red spot on the puncture as well as pain, swelling and overheating. The pain can even affect the entire muscle that the vaccine is being injected into for two to three days.
Serious undesirable side effects are rare. These are mostly based on an allergy to chicken protein or another ingredient in the flu vaccine, unknown to the vaccinated person. Such an allergic reaction can be very similar to the local inflammatory reaction and only cause discomfort at the injection site. In the worst case, it can lead to an allergic shock with life-threatening circulatory shock and shortness of breath.

Are you contagious during the flu shot?

The flu shot, even a live vaccine, is a weakened form of the flu virus. They are mostly the same shape as the actual flu viruses, but are nowhere near as aggressive. So after the vaccination you do not carry the flu yourself and therefore cannot infect anyone with the disease.

Influenza vaccination in children

There are also guidelines from the STIKO for the use of the flu vaccination in children. She recommends this for seriously ill children from the age of 6 months. However, only half the adult dose should be used for children aged 6 to 36 months. From the 36th month onwards, the full dose can be used. If the children are vaccinated against the flu for the first time, it is suggested to have two vaccinations against the flu every 4 weeks.The STIKO recommends vaccination with a live influenza vaccine for children aged 2-6, provided they are vaccinated against influenza viruses and there is no contraindication to a live vaccine.

Flu vaccination during pregnancy

Pregnancy poses an increased risk for the woman to suffer a severe disease course with pronounced symptoms when infected with the flu virus. This increased risk is due to the fact that the body changes naturally during pregnancy, making the woman's body more susceptible to infections with various pathogens.

A flu vaccination is therefore particularly recommended for pregnant women. A positive benefit of the vaccination is not only the protection for the pregnant woman, but also the subsequent protection for the newborn. The antibodies against the influenza virus formed by the maternal body can get into the child's blood via the placenta and thus represent a kind of nest protection for the baby after birth. In contrast to the so-called live vaccines used in some other vaccinations, the is at The vaccine used for the flu vaccine is a dead vaccine and can therefore generally be used throughout pregnancy. A vaccination can therefore in principle be carried out at any time during pregnancy. The STIKO recommends a flu vaccination from the 2nd trimester of pregnancy.

Read more about the Flu vaccination during pregnancy.

Flu vaccination while breastfeeding

In principle, a flu vaccination can also be carried out while breastfeeding. So if you haven't had yourself vaccinated during pregnancy, you can do so while breastfeeding. This should be done especially if the newborn is very young during the flu season. If the baby is under six months old, they cannot be vaccinated against the flu themselves. Instead, the environment, including the breastfeeding mother, should be vaccinated. This means that the baby is less likely to catch the flu. All vaccines that are used on the mother are considered safe for the infant.

When can you do sports again?

If you are ill, it is often recommended not to exercise or to exert yourself excessively. A vaccination is not a disease, however, so there is no strict ban on sports. However, after a vaccination, you should not necessarily do heavy endurance sports or exercise with heavy weights. This can lead to a worsening of a vaccination reaction. It cannot be ruled out that this will make the pain around the vaccination site worse and last longer. So if there is a need to exercise immediately after a vaccination, then it is advisable to reduce the intensity of the planned sport.

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