An immune system that isn’t functioning correctly. You can be immunocompromised by diseases like AIDS or taking some anti-cancer drugs, but you can also be immunocompromised by losing sleep, not drinking enough water and eating poorly. Pregnant women aren’t considered immunocompromised, but changes to their immune system can make them more susceptible to some diseases.

People with a weakened immune system are sometimes described as being immunocompromised. Cancer patients in active treatment, people being treated for autoimmune conditions like lupus, pregnant women and others may have weaker immune systems, which may make them more vulnerable to COVID-19 transmission or symptom severity.

An immune system that is weakened or impaired, meaning its ability to fight off infection may be more limited. The condition can be caused by viruses (such as HIV) or bacteria.