Table 1.

Definitions of Long COVID-19.

Name	Symptoms/ clinical manifestation	Time after COVID-19	COVID-19 severity	Reference
Post COVID-19 condition/syndrome	fatigue, shortness of breath, cognitive dysfunction or other symptoms affecting everyday functioning	> 3 months, lasting at least 2 months	mild-severe	WHO, 2021 https://www.who.int/publications/i/item/WHO-2019-nCoV-Post_COVID-19_condition-Clinical_case_definition-2021.1
	fatigue, exertion intolerance, partly meeting the criteria for ME/CFS	4–15 months	mild-moderate	[91]
	fatigue, exertion intolerance, partly meeting the criteria for ME/CFS	7–19 months	mild-moderate	[86]
	respiratory symptoms, pulmonary abnormalities	3–6 months	severe	[94]
	Mainly cognitive and neurological symptoms	> 3 months	na	[84]
Post-acute sequelae of COVID-19 (PASC)	one or more of the following: constitutional, respiratory, cardiopulmonary, gastrointestinal, genitourinary, reologic, rash, musculoskeletal symptoms, trouble sleeping	> 3 months	mild-severe	[78]
	respiratory, gastrointestinal, neurological symptoms, anosmia/dysgeusia	2–3 months	mild-severe	[20]
	pulmonary and extrapulmonary symptoms	2–3 months	severe	[96]
	fatigue, respiratory, digestive, neurological, skin and mucous membrane, circulation symptoms	> 1 months	mild	[76]
	different symptoms including fatigue, dyspnea, respiratory, body aches	> 1 months	mainly mild-moderate	[79]
	respiratory symptoms, interstitial lung changes	3–12 months	mild-severe	[95]
	pulmonary and extrapulmonary symptoms	2–3 months	severe	[96]
	According to WHO case definition	> 6 months	mild-severe (mainly hospitalized)	[97]
Long COVID	fatigue, dyspena, chest pain	> 4 months	mild-severe	[77]
	breathing difficulties/breathlessness, fatigue/malaise, chest/throat pain, anxiety/depression, headache, myalgia, other pain, cognitive, abdominal symptoms	3–6 months	mild-severe	[71]
	33 symptoms based on WHO case definition for post COVID-19 condition	> 4 months	mild	[18]
	with and without cognitive symptoms (e.g. "brain fog")	na	mainly mild	[93]
	Physical symptoms (e.g. arthralgia/myalgia, fatigue, cough), exertion intolerance	12 months	severe	[80]
	e.g. fatigue, neurological, cardiopulmonary, gastrointestinal symptoms, trouble sleeping	∼4 months	mild-severe	Peluso et al., 2022
	Fatigue, cough, shortness of breath	3–12 months	mild-severe	[85]
	One or more symptoms of the following e.g. pulmonary, systemic, neurological or psychiatric symptoms	12 months	mild and moderate/severe	[83]
Post-acute COVID-19 syndrome	different symptoms including fatigue, memory issues, loss of smell, abdominal pain	∼7 months	mainly mild	[81]