The challenges of diagnosing Pulmonary Embolism (PE) is discussed throughout this book. A whole chapter is designated to just masqueraders of PE. There are other textbooks dedicated to just infections and sepsis. This section reviews combined infections and PE. During the time of this text creation, the coronavirus was devastating lives and health care systems across the world. It affected every one of all demographics and no one was protected from its mayhem. Hospital based care providers have long recognized the connection between infection and clotting risks, but ideal diagnostic and treatment plans are hard to standardize across all patients. There are many nuances that affect care. Rather than review each disease specifically, a decision was made to focus mostly on COVID. The latter half of this chapter covers how other infections can produce similar PEs. The logic used to cover the COVID section can then be applied to other infection states. There are few papers that focus on specific interventions based on specific triggers with the exception of PE in the setting of malignancy and now COVID.