Fever after vaccination
After the flu vaccination, systemic reactions of the immune system occur in addition to local inflammatory reactions. Fever is one of the most effective defense mechanisms of the body. The immune system identifies the processed viruses from the influenza vaccine as potentially threatening pathogens.
Since most pathogens are mainly composed of proteins, their function is strongly dependent on the prevailing ambient temperature. For this reason, the body tries to make the environmental conditions for the pathogens as negative as possible and increases the body temperature. This is how the fever comes about as a side effect of the flu vaccination. It usually lasts for a maximum of two to three days.
Headache and aching limbs (muscle pain)
Headaches and aching limbs are a typical symptom of influenza. In a weakened form they can also occur with the flu vaccination. The flu vaccination is carried out with processed and thus attenuated flu viruses so that the body gets to know the surface structure of the pathogens.
The immune system is activated in the same way as it would be with the real flu. However, since it is an attenuated pathogen, the physical reaction is far less pronounced than with influenza. Nevertheless, symptoms such as fever, fatigue, headache and aching limbs can occur. Muscle aches are also typical, although these occur particularly in the muscle into which the flu vaccine was injected.
Guillain-Barré Syndrome
Guillain-Barré Syndrome (GBS) is an inflammatory nerve disease. It can cause temporary damage to the nerves, for example after an infection. The nerve roots, which originate from the spinal cord, are particularly affected by the inflammatory changes.
The main symptom is paralysis, which begins in the legs and continues to rise. Due to the inflammatory cause of the disease, GBS was also discussed as a possible consequence of the flu vaccination. However, no correlation between GBS and the vaccination was found.
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