TABLE 1.

Characteristics of included studies

Author, year	Country	Study design	Population included	Outcomes of interest for this review					Funding source
				Frequency of long COVID‐19 a	Main signs/symptoms of long COVID‐19 evaluated/observed	Temporal criteria used for long COVID‐19 or time point to measure signs/symptoms	Mean duration of long COVID‐19	Main aspects investigated as a potential risk factor for long COVID‐19
Bellan, 2021 25	Italy	Prospective cohort	COVID‐19 participants Participants recovered from severe COVID‐19, requiring hospitalisation during the acute phase n = 256	No	Ageusia Anosmia Arthralgia Chest pain Cough Diarrhoea Dyspnea Myalgia Pulmonary dysfunction Post‐traumatic stress	16 weeks after hospital discharge	No	Chronic Kidney Disease COPD Diabetes ICU admission during the hospital stay Modality of oxygen delivery Number of comorbidities Sex Smoking status	AGEING Project, Department of Excellence, Department of Translational Medicine, Università del Piemonte Orientale and by the Azienda Ospedaliero–Universitaria Maggiore della Carità di Novara
Carfi, 2020 4	Italy	Prospective cohort	COVID‐19 participants Participants recovered from severe COVID‐19, requiring hospitalisation during the acute phase n = 143	Yes	Anosmia Arthralgia Chest pain Cough Diarrhoea Dyspnea Dysgeusia Fatigue Headache Lack of appetite Myalgia Rhinitis Red eyes Sicca syndrome Sputum production Sore throat Vertigo	5.1 weeks (mean) after hospital discharge	No	No	Not reported
Carvalho‐Schneider, 2020 26	France	Prospective cohort	COVID‐19 participants Participants recovered from COVID‐19, requiring or not hospitalisation during the acute phase n = 130	Yes	Anosmia/ageusia Arthralgia Asthenia Chest pain Cutaneous signs Diarrhoea Dyspnoea Flulike symptoms (myalgia, headache) Palpitations	8 weeks after acute phase onset	No	Age Comorbidities Hospital admission at the acute phase Initial abnormal auscultation Signs and symptoms at the acute phase	Not reported
El Sayed, 2020 27	Saudi Arabia	Retrospective cohort	Long COVID‐19 participants COVID‐19 after 2 consecutive negative PCR tests who attended for pulmonology clinic for follow‐up and psychiatric department for assessment. n = 200	No	Fatigue Anhedonia	11.8 weeks (mean) after 2 consecutive negative PCR tests	No	Age Educational level Sex Smoking status	Not reported
Garrigues, 2020 28	France	Retrospective cohort	COVID‐19 participants Participants recovered from COVID‐19, requiring hospitalisation during the acute phase. n = 120	No	Anosmia Chest pain Concentration impairment Cough Dysgeusia Dyspnoea Fatigue Hair loss Memory impairment Sleep disorders	14.2 weeks after hospital admission	No	ICU‐admission	Not reported
Guedj, 2020 29	France	Retrospective cohort	Long‐COVID‐19 participants Participants recovered from COVID‐19, requiring hospitalisation during the acute phase. n = 35	No	Dyspnoea Hyposmia/anosmia Insomnia Memory/cognitive impairment Pain Post‐traumatic stress disorder	3 weeks after acute phase onset	No	No	The local PET database of healthy controls was funded by Assistance Publique – Hopitaux de Marseille
Halpin, 2020 30	United Kingdom	Retrospective cohort	COVID‐19 participants COVID‐19 requiring hospitalisation during the acute phase n = 100	No	Concentration impairment Continence impairment Dyspnoea Fatigue Faecal/Urinary incontinence Memory impairment Neuropsychological symptoms Pain Speech‐ and swallow‐ related symptoms	At least 4 weeks after hospital discharge	No	No	National Institute for Health Research (NIH) infrastructure at Leeds and Sheffield
Huang, 2021 31	China	Retrospective cohort	COVID‐19 participants COVID‐19 requiring hospitalisation during the acute phase n = 1733	Yes	Ageusia Anosmia Anxiety or depression Arthralgia Chest pain Dyspnoea Diarrhoea or vomiting Dizziness Fatigue or muscle weakness Fever Hair loss Headache Lack of appetite Mobility impairment Myalgia Palpitations Pain or discomfort Respiratory dysfunction Skin rash Sleep disorders Sore throat or difficult to swallow	24 weeks after hospital discharge	No	Age Severity of acute COVID‐19 infection Sex	National Natural Science Foundation of China; Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences; the National Key Research and Development Programme of China; Major Projects of National Science and Technology on New Drug Creation and Development of Pulmonary Tuberculosis; Peking Union Medical College Foundation
Jacobs, 2020 32	United States of America	Retrospective cohort	COVID‐19 participants COVID‐19 requiring hospitalisation during the acute phase n = 183	Yes	Anosmia Arthralgia Confusion Cough Diarrhoea Dysgeusia Dyspnoea Eye irritation Fatigue Fever Headache Myalgia Sputum production Ulcer	4 weeks after hospital discharge	No	Age Comorbidities Oxygen requirements during and after hospitalisation Sex	Not reported
Liang, 2020 33	China	Prospective cohort	COVID‐19 participants COVID‐19 requiring hospitalisation during the acute phase n = 76	No	Chest pain on exertion Cough Diarrhoea Dyspnoea Fatigue Fever Sputum production Palpitations Respiratory dysfunction	12 weeks after hospital discharge	No	Age Comorbidities Hospital length of stay Severity of acute COVID‐19 infection Sex Treatment received in the acute phase	Not reported
Lu, 2020 34	China	Prospective cohort	COVID‐19 participants COVID‐19 requiring hospitalisation during the acute phase n = 60	Yes	Anosmia Dysgeusia Fatigue Headache Hearing loss Mobility impairment Limb numbness Memory impairment Myalgia Mood changes Vision changes Tremor	12 weeks after hospital discharge	No	No	Shanghai Natural Science Foundation, Youth Programme of National Natural Science Foundation of China, Shanghai Sailing Programme, Shanghai Science and Technology Development, Shanghai Municipal Science and Technology Major Project and ZJ Lab
Moreno‐Perez, 2021 35	Spain	Prospective cohort	COVID‐19 participants COVID‐19 requiring or not hospitalisation during the acute phase n = 277	Yes	Anosmia Arthralgia Cough Diahrrea Dysgeusia Dyspnoea Fatigue Myalgia Neurological symptoms (headache, memory or cognitive impairment)	10‐14 weeks after discharge from hospital or ambulatory	No	Age Comorbidities Sex Severity of acute COVID‐19 infection COVID‐19 GRAM score Inflammatory markers ICU‐admission in the acute phase ICU length of stay Treatment received in the acute phase	No external funding was received
Nehme, 2020 36	Switzerland	Prospective cohort	COVID‐19 participants Participants recovered from severe COVID‐19, requiring hospitalisation during the acute phase n = 669	Yes	Ageusia Anosmia Cough Digestive symptoms Dyspnea Fatigue Fever Headache	4‐6 weeks after acute phase onset	No	No	Not reported
Otte, 2020a 37 /Otte, 2020b 38	Germany	Retrospective cohort	COVID‐19 participants Participants recovered from COVID‐19, not requiring hospitalisation during the acute phase n = 91	No	Olfactory dysfunction	At least 3 weeks after recovery	No	No	Not reported
Petersen, 2020 39	Denmark	Prospective cohort	COVID‐19 participants Participants recovered from COVID‐19, not requiring hospitalisation or not during the acute phase n = 187	Yes	Anosmia Arthralgia Cough Diarrhoea Dysgeusia Dyspnea Fatigue Fever Headache Myalgia Nausea Rash Throat pain	14.2‐17.8 weeks after acute phase onset	No	Age Comorbidities Hospitalisation Self‐reported medication use Sex Smoking status	Krúnborg and Bortartún
Puchner, 2021 40	Austria	Prospective cohort	COVID‐19 participants Participants recovered from severe COVID‐19, requiring hospitalisation during the acute phase n = 23	No	Neuropsychological dysfunction Pulmonary dysfunction Sleep disorder	3‐4 weeks after hospital discharge	No	No	No funding
Ramani, 2021 41	United States of America	Case series	COVID‐19 participants Participants recovered from COVID‐19, requiring hospitalisation during the acute phase n = 28	No	Cognitive dysfunction Depression Insomnia Physical dysfunction Pulmonary dysfunction	6 weeks after hospital discharge	No	No	No funding
Rosales‐Castillo, 2021 42	Spain	Retrospective cohort	COVID‐19 participants Participants recovered from COVID‐19, requiring hospitalisation during the acute phase n = 118	Yes	Ageusia Anosmia Asthenia Cough Dyspnea Myalgia	7 weeks (mean) after hospital discharge	No	No	Not reported
Roth, 2021 43	United States of America	Case series	Long‐COVID‐19 participants Participants recovered from severe COVID‐19, requiring hospitalisation during the acute phase n = 3	No	Cholestasis	Not specified	No	Ischemic hepatitis	No funding
Simani, 2021 44	Iran	Retrospective cohort	COVID‐19 participants Participants recovered from COVID‐19, requiring hospitalisation during the acute phase n = 120	No	Chornic fatigue syndrome Post‐traumatic stress disorder	24 weeks after disease onset	No	Comorbidity Post‐traumatic stress disorder Sex	Not reported
Suarez‐Robles, 2020 45	France	Retrospective cohort	COVID‐19 participants Participants recovered from COVID‐19, requiring hospitalisation during the acute phase n = 134	No	Anosmia Arthralgia Cough Cutaneous manifestations Dyspnea Dysgeusia Dysphonia Fatigue Headache Palpitation Psychological symptoms Sputum production Walking disturbances	12 weeks after hospital discharge	No	No	Not reported
Tarazona‐Fernandez, 2020 46	Spain	Retrospective cohort	COVID‐19 participants Participants recovered from COVID‐19, not requiring hospitalisation during the acute phase n = 37	Yes	Anxiety Arthralgia Asthenia Chest pain Cough Depression Diahrrea Dyspnea Fever Headache Myalgia Red eyes Sore throat	5.7 weeks (mean) after disease onset	No	No	No funding
Van den Borst, 2020 47	Netherlands	Prospective cohort	COVID‐19 participants Participants recovered from COVID‐19, requiring or not hospitalisation during the acute phase n = 124	No	Anxiety/Depression Dyspnea Cognitive impairment Physical dysfunction Pulmonary dysfunction	9.1 (1.6) weeks (mean/SD) after hospital discharge	No	COVID‐19 severity status in the acute phase	No funding
Xiong, 2021 48	China	Retrospective cohort	COVID‐19 participants Participants recovered from non‐critical COVID‐19, requiring hospitalisation during the acute phase n = 538	No	Cardiovascular‐related symptoms General symptoms (arthralgia, chills, dizziness, fatigue, limb oedema, myalgia, sweating) Hair loss Psychosocial symptoms Pulmonary dysfunction	More than 12 weeks after hospital discharge	No	Age COVID‐19 severity status in the acute phase Sex Signs and symptoms at the acute phase	Not reported
Zhao, 2020 49	China	Retrospective cohort	COVID‐19 participants Participants recovered from non‐critical COVID‐19, requiring hospitalisation during the acute phase n = 55	No	Ageusia Anosmia Cough and sputum Dyspnea Gastrointestinal symptoms Fatigue Headache Pulmonary dysfunction	12 weeks after hospital discharge	No	Age Comorbidities Hospital length of stay Sex Signs and symptoms at the acute phase	Key Scientific Research Projects of Henan Higher Education Institutions (under grant 20B320032)

Abbreviations: COPD, chronic obstructive pulmonary disease; CT, computerised tomography; D_lco, diffusing lung capacity for carbon monoxide; HFNC, high‐flow nasal cannula; ICU, intensive care unit; IMV, invasive mechanical ventilation; NIV, non‐invasive mechanical ventilation; MRI, magnetic resonance imaging; SD, standard deviation; SPPB, short physical performance battery; US, ultrasonography; VHA, veteran health administration.

^a Frequency of long COVID‐19, or post‐acute COVID‐19 or persistence of clinical manifestations after the acute phase (as defined by the authors of primary studies).