Introduction
The occurrence of elevated temperatures or fever after a vaccination in adults is called a normal general reaction to the vaccine. Together with local reactions such as a reddened, painful, swollen injection site or swollen lymph nodes near the vaccination site, these are called temporary, usually harmless “side effects”.
Cause
The cause of an elevated temperature as a general reaction to the administered vaccine lies in the activation of the body’s own immune system. The fact that the vaccine supplies the body with either attenuated live viruses (live vaccine) or only viral components (dead vaccine) and the immune system recognizes these as harmful invaders and begins to fight them, can cause the same or similar symptoms as in a normal viral or bacterial cold. However, this immune reaction to the administered vaccine is intentional: because the administered virus or virus components are recognized as foreign, the defense system forms certain defensive substances, the so-called antibodies, against these very intruders. At the same time, a kind of “memory” for this pathogen is formed in the immune system, so that in the event of a possible later re-infection with the same virus, antibodies can be formed more quickly and efficiently and the body is thus prepared for this infection. The fever after vaccination is thus an expression of the active immune defence and of the fact that the vaccine is being administered, which can therefore be regarded as a completely physiological reaction of the body: by increasing the body temperature, the body’s defence cells and enzymes become more active and efficient, more defence cells are formed, metabolic processes are accelerated, while viruses and bacteria feel less comfortable and are inhibited in their reproduction.
When does fever occur in adults after vaccination?
The fever that can develop after a vaccination, you belong to the possible vaccination reactions that can occur after a vaccination. These reactions include fever, reddening of the injection site, muscle pain (comparable to a muscle ache) and flu-like symptoms. Usually these reactions occur within 72 hours after vaccination and should not last longer than 1-2 days. You can find more articles on this topic here: How to measure fever ; How to reduce fever Only if the fever persists for several days, the injection site is swollen and overheated or there is a massive feeling of illness, a doctor should be consulted.
