[theold]

If the effectiveness is low and the number of cases is low, the RKI reports the vaccination effectiveness as zero - even if it could be negative. 

This happened most recently in the five to eleven year old age group. The authority is now being criticized for this.

How effective is the vaccination against the omicron variant? By comparing the proportion of vaccinated people among all Covid-19 cases (vaccination breakthroughs) with the proportion of vaccinated people in the population, the Robert Koch Institute (RKI) tries to roughly estimate the so-called vaccination effectiveness.


https://www.welt.de/wissenschaft/plus238...ndern.html