More than one year since its emergence, corona virus disease 2019 (COVID-19) is 
still looming large with a paucity of treatment options. To add to this burden, 
a sizeable subset of patients who have recovered from acute COVID-19 infection 
have reported lingering symptoms, leading to significant disability and 
impairment of their daily life activities. These patients are considered to 
suffer from what has been termed as "chronic" or "long" COVID-19 or a form of 
post-acute sequelae of COVID-19, and patients experiencing this syndrome have 
been termed COVID-19 long-haulers. Despite recovery from infection, the 
persistence of atypical chronic symptoms, including extreme fatigue, shortness 
of breath, joint pains, brain fogs, anxiety and depression, that could last for 
months implies an underlying disease pathology that persist beyond the acute 
presentation of the disease. As opposed to the direct effects of the virus 
itself, the immune response to severe acute respiratory syndrome coronavirus 2 
(SARS-CoV-2) is believed to be largely responsible for the appearance of these 
lasting symptoms, possibly through facilitating an ongoing inflammatory process. 
In this review, we hypothesize potential immunological mechanisms underlying 
these persistent and prolonged effects, and describe the multi-organ long-term 
manifestations of COVID-19.