Some COVID-19 vaccines use a modified (stabilised) variant of the Coronavirus SARS-CoV-2 spike protein as a target antigen structure. In SARS-CoV-2 infections, the immune system recognises the unmodified form of the spike protein as an antigen. Researchers at the Paul-Ehrlich-Institut were able to observe that antibodies formed post-vaccination recognise different spike protein linear structures than antibodies formed post-infection. The comparison was made with antibodies in the serum of individuals vaccinated with Comirnaty (BioNTech/Pfizer) and antibodies in serum from COVID-19 convalescents. A report on the findings appears in the online edition of Vaccines from 1 December 2021.