Many people have unpleasant reactions after being vaccinated against Covid-19. They complain of muscle pain, fever, headache or tiredness. However, some feel no change at all after the injection – and worry whether this means that they have poor vaccination protection. Is this assumption correct?
CLAIM: You need noticeable vaccination reactions for strong protection against the coronavirus.
FACTS: It is true that fever and fatigue, for example, are signs that the body is fighting back. The symptoms usually come from a certain part of the immune system, the so-called “innate immune system”. This is activated first after a vaccination and signals the body of a potential danger from a foreign intruder, explains Peggy Riese, an expert on vaccinations at the Helmholtz Center for Infection Research in Braunschweig.
After vaccination, the vaccine is such an intruder for this part of the immune system. As such, it not only perceives the virus antigen that triggers the protective effect, says Riese, but also, for example, active ingredient enhancers or auxiliary substances such as stabilizers. So this part of the immune system reacts immediately, but in a more general way. Why some people are more prone to vaccination reactions while others hardly feel anything is not yet fully understood, according to Riese.
The specific protection against the Sars-CoV-2 pathogen, on the other hand, is only generated over time by the cells of the so-called “acquired immune system”. In the process, the body learns to continue to produce tailor-made antibodies in the event of such an infection and, for example, to kill infected body cells with the help of special T cells, the killer cells.
Both types of the immune system are in a very complex, not yet fully explored exchange with one another. In fact, the vaccination reaction of the innate immune system is the trigger for the acquired system to become active – but this impulse is often not or barely noticeable.
“Even if you have no or only very mild side effects such as slight pain at the injection site or headache, you are protected with the same probability as people who have stronger vaccine reactions such as fever, malaise and joint pain,” explains researcher Riese.
Symptoms after a vaccination are “not an indicator of the strength of the vaccination protection”, confirms Christine Falk, President of the German Society for Immunology. People could be completely symptom-free and still develop strong protection. Conversely, in studies on the approval of the Covid 19 vaccines, people also showed symptoms who would only have received a placebo.