Immunity to Infection in Healthy Participants and Participants With Cancer

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).