The term ‘immune compromised’ refers to individuals whose immune system is considered weaker, more impaired, or less robust than that of the average healthy adult. The primary role of the immune system is to help fight off infection. Individuals with compromised immune systems are at a higher risk of getting infections, including viral infections such as COVID-19. There are many reasons that a person might be immune compromised: health conditions such as cancer, diabetes, or heart disease, older age, or lifestyle choices such as smoking can all contribute to weakened immune systems. Patients with cancer may be at greater risk of being immune compromised depending on the type of cancer they have, the type of treatment they receive, other health conditions, and their age. The risk of being immune compromised is typically highest during the time of active cancer treatment, such as during treatment with chemotherapy. There is no specific test to determine if a person is immune compromised, although findings such as low white blood cell counts or low levels of antibodies (also called immunoglobulins) in the blood likely indicate an immune compromised state.