Flu: These are the symptoms
Influenza is an acute infection of the respiratory tract, triggered by viruses. It is very contagious. The incubation period of a flu including symptoms, i.e. the time from infection with the pathogen to the first flu signs, is one to three days. In contrast to a simple cold (flu-like infection), an influenza comes suddenly and with a much more severe clinical picture. For this reason, those affected should see a doctor. Flu symptoms, such as a strong general feeling of illness, aching limbs and muscles, speak for a flu diagnosis. Adults get high fever and dry cough when the flu gets them. In children, however, the symptoms can be completely uncharacteristic, for example abdominal pain or rash. Flu can also cause diarrhoea or nausea and vomiting.
The following symptoms are indicative of influenza:
- fever, often up to 40 degrees
- Tiredness (sometimes lasts for weeks during flu)
- aching limbs, occasionally flu is accompanied by back pain
- Cough (dry cough with little or no sputum is typical of influenza)
- Sweating and chills
- sometimes sore throat, difficulty swallowing and rhinitis
Children may also have unspecific symptoms of influenza, e.g:
- Rash (on the first day of illness, vesicles may form in the mouth, experts speak of flu exanthema)
As the immune system of children is not yet fully developed, consequences can occur in the case of a flu such as earache (inflammation of the middle ear), sinusitis, pneumonia or – especially in small children – pseudocroup, a respiratory disease with barking cough and shortness of breath.
In the case of influenza, however, not all of the flu symptoms mentioned need to occur. Sometimes, for example, influenza runs without a cold. Also, only a third of those affected get a high fever. A further third fall ill with a slight fever, while the last third get the flu without fever.
In case of flu, vaccination is the best way to prevent it. The vaccine needs two weeks to build up a reliable protection. Those who are vaccinated should do so in November or December. Then the vaccine develops its effect until the flu season starts around the turn of the year. Those who are later can catch up on the flu vaccination as quickly as possible.
Attention: Flu viruses are mutable. The vaccination must therefore be repeated every year!
According to the Robert Koch Institute (RKI), the risk of contracting influenza can be roughly halved in older people; in young adults, the protective effect is 80 percent if the vaccine matches the circulating influenza viruses very well. The difference in effectiveness is thought to be due to the reduced immune response of older people, the vaccine does not work quite as reliably.
The vaccines approved in Germany are usually dead vaccines, i.e. they contain inactivated viruses. There are 3-fold and 4-fold vaccines. The triple vaccine protects against three different influenza subtypes or lines (two A and one B line). The flu vaccination with 4-fold vaccine provides additional protection against another B type. Since the 2018/19 flu season, health insurance companies have had to reimburse the flu vaccination with a 4-fold vaccine.
A flu vaccination has hardly any side effects, the vaccine is well tolerated. As with other vaccinations, the flu vaccination can cause slight pain or swelling at the vaccination site. Sometimes a redness also occurs. In rare cases the vaccinated person feels a little unwell after administration of the live vaccine, which is also available, and develops a slight fever, shivers, sweats, feels tired or has headaches, muscle pain or aching limbs. The symptoms usually subside within one or two days.
Flu vaccination during pregnancy
A flu vaccination during pregnancy is not dangerous for either the mother or the child. On the contrary: the Standing Commission on Vaccination (STIKO) even advises all expectant mothers who are pregnant during the flu season to get vaccinated against the flu.
Not only the mother but also the newborn child benefits from a vaccination against influenza during pregnancy. The body passes the antibodies on to the unborn child via the placenta. In this way, the baby is protected against the flu in the first months after birth. Even nursing mothers can be vaccinated against flu without any problems.
Flu vaccination for children and babies
Flu vaccination for children is possible from the age of six months. The flu vaccination is normally also unproblematic for babies. In addition to the dead vaccine, nasal flu vaccination by nasal spray is available for children and adolescents between the ages of two and 17. This means that the doctor sprays a live vaccine into their nose. The live vaccine (LAIV) is the preferred choice when injecting a dead vaccine is problematic, for example in cases of coagulation disorders or injection phobia.
Is influenza contagious?
Flu is a very contagious disease. Infants, toddlers, the elderly and people with immune deficiency or a basic condition such as heart or vascular disease are particularly susceptible.
The flu viruses spread mainly by droplet infection. This means that when a person coughs or sneezes, the pathogens are released into the air via tiny droplets of saliva and bystanders breathe them in. The flu viruses can also be spread by shaking hands or through surfaces such as door handles that many people touch. This type of flu transmission is called smear or contact infection.
Once the viruses are in the body, the flu has an incubation period (the time from infection to the appearance of the first symptoms) of one to three days. Tricky: infected persons are already contagious even if they do not yet show any symptoms of the flu. How long someone is contagious depends on the pathogen and the immune defence of the person affected. A flu lasts on average seven to 14 days. People who are ill are particularly contagious during the first four to five days, as they then cough up large quantities of virus. Children can spread the viruses a little longer. In principle, the stronger the symptoms, the more infectious.