Many cancer patients are highly susceptible to infection and respond poorly to vaccination. This observational study will determine molecular and cellular features of immunity to viral pathogens in participants with cancer and compare them to healthy controls. The aim is to identify how antiviral immunity in participants with cancer differs from that in healthy participants to understand why cancer patients are more susceptible to infections. In this context, the investigators will also evaluate immunity to medically indicated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and seasonal influenza vaccine received by study participants during standard care (vaccines are not part of the study).

Cancer and its treatments are associated with dysregulated immune systems, and cancer patients are highly susceptible to infections (e.g., influenza, SARS-CoV-2). Importantly, cancer patients often respond poorly to vaccination. The molecular and cellular mechanisms underlying immune dysregulation and poor immunity in cancer patients are manifold, variable among individual patients/conditions, and poorly understood. An in-depth understanding of these mechanisms is essential to identifying novel strategies to prevent infectious diseases and developing individualized therapies.

In this observational study, the investigators will collect blood samples from 200 participants with hematological and oncological malignancies and healthy participants and analyze the cellular and humoral immune status in the context of SARS-CoV-2 and influenza infection and vaccination within these samples using systems biological tools. Medically indicated vaccination against SARS-CoV-2 and influenza during study participation is allowed.

This study aims to (1) examine the fundamental innate, cellular, and humoral immune responses to pathogens that form the basis of immunological memory and (2) identify molecular and cellular mechanisms responsible for the reduced immune immunity to viral pathogens in participants with cancer.

Inclusion Criteria:

• You are aged 18 years or older.
• You are able to understand and give informed consent.
• Participants with cancer: you are suffering from cancer
• Healthy participants: you are a healthy individual.

Exclusion Criteria:

• You are unable to give informed consent.
• You have been suffering from an acute infection with fever during the last three days.
• You have a Hb level of less than 9 g/dl.
• You have a human immunodeficiency virus (HIV) or hepatitis C virus (HCV) infection.

Participants with cancer will be drawn from the local clinics at the University Hospital Tübingen. Healthy participants will be recruited from university and hospital employees not associated with the study.