COVID-19 immunization in people with cancer-Is it safe and efficient? What do we know?

Prior to the COVID-19 pandemic, vaccination of people with cancer or a recent history of cancer was advisable under specific conditions, depending on the type of vaccine (inactivated or live attenuated virus or bacterium), type of cancer, and whether they had undergone treatment for cancer. Some malignancies, especially hematological malignancies, and cancer treatments such as chemotherapy, radiotherapy, and splenectomy negatively impact the immune response. The clinical trials of currently used vaccines against COVID-19 did not include people with active cancer; thus, there is an important gap in the knowledge of safety and efficiency data for COVID-19 immunization in this population. However, considering the risk of mortality and morbidity due to possible infection with SARS-CoV-2, medical experts recommend immunization on an individual basis. As the worldwide prevalence of malignancies is high, reliable information on COVID-19 vaccination is expected to be revealed in future clinical trials. In this review, we examine the key aspects of cancer that may be affected by COVID-19 and summarize the current literature on COVID-19 immunization.