In this issue of Infectious Disease Clinics of North America, guest editors Drs. Naomi P. OGrady and Sameer Kadri bring their considerable expertise to the topic of Complex Infectious Diseases Issues in the Intensive Care Unit. Affected immunity of patients with COVID-19 has made management of complex infectious diseases in the intensive care unit more important than ever. This issue provides key updates for managing these complex infectious diseases and includes current clinical information for COVID-19 patients, making this a state-of-the-art collection of review articles for practicing infectious disease physicians.