Abstract
Patients with cancer are at an increased risk to suffer severe coronavirus disease 2019 (COVID-19). Therefore, specific preventative measures including COVID-19 vaccines are especially important. Both anticancer therapies and the underlying malignancy itself can lead to significant immunosuppression posing a particular challenge for vaccination strategies in these patients. At the moment, four COVID-19 vaccines are European Medicines Agency (EMA) approved in Germany: two mRNA and two viral vector-based vaccines. All four vaccines show excellent protection against severe COVID-19. Their mechanism of action relies on the induction of the production of virus-specific proteins by human cells and the following activation of a specific adaptive immune response. Vaccination against COVID-19 has been prioritized for cancer patients and medical personnel in Germany. Regarding timing of vaccination, vaccination prior to initiation of anticancer therapy seems ideal in newly diagnosed disease. However, due to the significant risk of severe COVID-19 in cancer patients, vaccination is also strongly recommended for patients already undergoing anticancer therapy. In these patients, immune response might be reduced. In two particular patient cohorts, namely stem cell transplant recipients and patients treated with B‑cell depleting agents, an interval of several months following therapy is recommended because otherwise the response to vaccination will most likely be severely reduced. Preliminary data suggest only low rates of seroconversion following a single shot of vaccine in cancer patients. Therefore, on the long run, repeat vaccination regimens might be preferable in cancer patients.