Since all clinical trials conducted during the development of anti-COVID-19 vaccines have adopted among the exclusion criteria the presence of immunodepression or immunomodulating therapy, to date, the effects of vaccination against the new coronavirus 2 in people under such conditions have yet to be clearly defined. The primary objective of the study is to assess the safety of treatment with biotechnological drugs in patients suffering from moderate–severe psoriasis and subjected to the prophylactic vaccination against SARS-Cov-2. Additionally, the secondary objective of the research is to investigate the existence of a possible impact of anti-COVID-19 vaccination on the natural chronic-relapsing course and the severity of the psoriatic disease. The study included 436 patients with moderate–severe psoriasis, both male and female, in treatment with biologics. The data were collected using the direct interview method. A reduction of 74.13% of average Psoriasis Area Severity Index (PASI )compared to baseline (T0) was found in all subjects; this does not differ significantly from the group that underwent vaccination (73.4%). Moreover; at the end of the study, neither mild nor severe adverse events (ADR) were observed among them. In conclusion, biotechnological drugs used in the management of patients with moderate–severe psoriasis demonstrate a high safety profile also in subjects immunized against SARS-Cov-2.