Long COVID in the context of "COVID-19"

The treatment and management of COVID-19 combines both supportive care, which includes treatment to relieve symptoms, fluid therapy, oxygen support as needed, and a growing list of approved medications. Highly effective vaccines have reduced mortality related to SARS-CoV-2; for those awaiting vaccination, as well as for the estimated millions of immunocompromised persons who are unlikely to respond robustly to vaccination, treatment remains important. Some people may experience persistent symptoms or disability after recovery from the infection, known as long COVID, but there is still limited information on the best management and rehabilitation for this condition.

Most cases of COVID-19 are mild. In these, supportive care includes medication such as paracetamol or NSAIDs to relieve symptoms (fever, body aches, cough), proper intake of fluids, rest, and nasal breathing. Good personal hygiene and a healthy diet are also recommended. As of April 2020 the U.S. Centers for Disease Control and Prevention (CDC) recommended that those who suspect they are carrying the virus isolate themselves at home and wear a face mask. As of November 2020 use of the glucocorticoid dexamethasone had been strongly recommended in those severe cases treated in hospital with low oxygen levels, to reduce the risk of death. Noninvasive ventilation and, ultimately, admission to an intensive care unit for mechanical ventilation may be required to support breathing. Extracorporeal membrane oxygenation (ECMO) has been used to address respiratory failure, but its benefits are still under consideration. Some of the cases of severe disease course are caused by systemic hyper-inflammation, the so-called cytokine storm.

A thrombus (pl. thrombi) is a solid or semisolid aggregate from constituents of the blood (platelets, fibrin, red blood cells, white blood cells) within the circulatory system during life. A blood clot is the final product of the blood coagulation step in hemostasis in or out of the circulatory system. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of cross-linked fibrin protein. The substance making up a thrombus is sometimes called cruor. A thrombus is a healthy response to injury intended to stop and prevent further bleeding, but can be harmful in thrombosis, when a clot obstructs blood flow through a healthy blood vessel in the circulatory system.

In the microcirculation consisting of the very small and smallest blood vessels the capillaries, tiny thrombi known as microclots can obstruct the flow of blood in the capillaries. This can cause a number of problems particularly affecting the alveoli in the lungs of the respiratory system resulting from reduced oxygen supply. Microclots have been found to be a characteristic feature in severe cases of COVID-19 and in long COVID.

Dysautonomia, autonomic failure, or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This condition may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. A number of conditions can feature dysautonomia, such as Parkinson's disease, Long COVID, multiple system atrophy, dementia with Lewy bodies, Ehlers–Danlos syndromes, autoimmune autonomic ganglionopathy and autonomic neuropathy, HIV/AIDS, mitochondrial cytopathy, pure autonomic failure, autism, and postural orthostatic tachycardia syndrome.

Diagnosis is made by functional testing of the ANS, focusing on the affected organ system. Investigations may be performed to identify underlying disease processes that may have led to the development of symptoms or autonomic neuropathy. Symptomatic treatment is available for many symptoms associated with dysautonomia, and some disease processes can be directly treated. Depending on the severity of the dysfunction, dysautonomia can range from being nearly symptomless and transient to disabling and/or life-threatening.