Physicians have summarized a list of unusual clinical observations of COVID-19 including but not limited to severely hypoxic (low oxygen) patients despite relatively normal lung compliance upon examination, thrombotic complications, and consistent autopsy findings of blood clots (thrombi) in the microcirculation of the lung. After an acute COVID-19 infection, over 200 different lingering symptoms have been reported for long COVID, which can persist for about 6?"24 months.