If the virus mutates in such a way that antibodies that were effective against the original virus in vaccinated or convalescent people, for example, are not as potent in fighting a new variant, a so-called immune escape has been created. This allows people to become infected and ill despite vaccination or surviving COVID-19. The Delta variant stands out due to its higher transferability as well as a kind of immune escape. “The mutation reduces the effect of some antibodies and thus also recognition by the immune system,” said immunologist Georg Behrens, professor at the Hannover Medical School at the Clinic for Rheumatology and Immunology, in an interview with DW.