One of the greatest weapons in the hands of human beings in the fight against corona virus is undoubtedly the vaccines developed. However, the different efficiency values from each vaccine cause confusion. There are even those who classify vaccines as “good” or “bad” based on these values alone. We will now look at these concepts that raise the most questions about vaccines. In particular, we will try to explain the differences between vaccine efficacy and effectiveness, which are not widely known, through current vaccines. NTV editor Ömer Faruk Şahin compiled this Focus File.