Table 2.
Summary of all studies providing data on Long COVID in children and adolescents included in this review.
| First Author | Study Period | Country | Number of Paediatric Patients/Type of Study Population | Study Type | Main SARS-CoV-2 Variant(s) | Definition Long COVID | Study Focus | Key Findings | Comments |
|---|---|---|---|---|---|---|---|---|---|
| Adler 2022 [25] | December 2021 to January 2022 | Israel | n = 1140 participants aged 5–18 years with previous SARS-CoV-2 infection n = 2092 controls without infection Online questionnaire |
Cross-sectional study |
Delta and Omicron variants | Symptoms >4 weeks after SARS-CoV-2 infection | Prevalence of Long COVID symptoms and associated factors |
Prevalence of most symptoms was higher in children with previous infection: headaches (18.4% vs. 5.4%, p < 0.001), weakness (15.1% vs. 3.3%, p < 0.001), fatigue (12.3% vs. 6.4%, p < 0.001), abdominal pain (9.5% vs. 3.8%, p < 0.001). Symptoms were more prevalent in adolescents (12–18 years) than in children aged 5–11 years. Symptoms more frequent in participants without infection: school malfunctioning, stress, social problems, and weight changes. |
Vaccination status included in analysis. |
| Ashkenazi-Hoffnung 2021 [26] | November 2020 to April 2021 |
Israel | n = 90 participants ≤18 years of age who presented to a designated clinic for Long COVID | Prospective study | n.d. | NIH definition | To describe the spectrum of persisting symptoms in children with Long COVID | Most common symptoms included: fatigue (71.1%), dyspnoea (50.0%) and myalgia (45.6%). Less common symptoms included: sleep disturbances (33.3%), chest pain (31.1%), paraesthesia (28.9%), headache (28.9%), hair loss (26.7%), anosmia-ageusia or parosmia/euosmia (25.6%), gastrointestinal symptoms (20.0%), dizziness (18.9%), weight loss (18.9%), memory impairment (17.8%), vasomotor complaints (14.4%), arthralgia (14.4%), tremor (13.3%), and cough (10.0%). |
No SARS-CoV-2 negative control group. Unclear if all participants had a final diagnosis of Long COVID. A substantial number of participants had pre-existing diagnoses, including asthma, ADHD, and anxiety/depressive disorders. |
| Atchison 2023 [27] | March 2021 to March 2022 | United Kingdom | n = 10,059 children and adolescents aged 5–17 years in the community (REACT-1 study) |
Serial cross-sectional study | Alpha, Delta, Omicron variants | Persistent symptoms lasting ≥3 months post SARS-CoV-2 infection | Estimate the prevalence of persistent symptoms after SARS-CoV-2 infection and identify associated risk factors | ≥1 persistent symptom lasting ≥3 months post infection in 4.4% (95% CI 3.7 to 5.1) of 3173 children aged 5–11 years and 13.3% (95% CI 12.5 to 14.1) of 6886 participants aged 12–17 years. Most common symptoms: age 5–11 years: persistent cough (27.4%), headaches (25.4%); age 12–17 years: loss or change of sense of smell (52.2%) and taste (40.7%) Risk factors for Long COVID: higher age and pre-existing health conditions. |
No SARS-CoV-2 negative control group. Included suspected COVID-19 cases that were unconfirmed. Included only participants who previously had symptomatic SARS-CoV-2 infection. |
| Bergia 2022 [28] | March to December 2020 | Spain | n = 451 children aged <18 years with symptomatic, confirmed (PCR, antigen test, serology) SARS-CoV-2 infection n = 98 controls without history of SARS-CoV-2 infection |
Retrospective study | n.d. | NICE and WHO definitions | To evaluate the prevalence of persistent symptoms after SARS-CoV-2 infection | 18.4% of participants in the COVID-19 group had one or more symptoms for 4–12 weeks, 14.6% for longer than 12 weeks. Only 8.2% had 2 or more symptoms for more than 12 weeks. Odds were higher for participants ≥5 years (OR 3.0), those admitted to hospital (OR 3.9), those admitted to the PICU (OR 4.3) and those with relatives with symptoms lasting for 12 weeks or more (OR 2.8). The following symptoms were more common in the COVID-19 group than in the control group: decreased appetite, myalgia, and asthenia. |
13 patients (2.9%) with MIS-C included. Included only patients who previously had symptomatic SARS-CoV-2 infection. |
| Borch 2022 [29] | January 2020 to March 2021 | Denmark | n = 15,041 children aged 0–17 years with confirmed SARS-CoV-2 infection n = 15,080 negative controls |
National cohort study | n.d. | NICE guideline | To evaluate persistent symptoms after SARS-CoV-2 infection | SARS-CoV-2-positive group: 3813/15,041 (25.4%) children reported symptoms lasting >4 weeks; 1323 (34.7%) reported one symptom, 1095 (28.7%) two symptoms and 1395 (36.6%) three or more symptoms. Control group: 3446/15,080 (22.9%) children reported symptoms lasting > 4 weeks; 1870 children (54.3%) reported one symptom, 794 children (23.0%) reported two symptoms, and 782 children (22.7%) reported three or more symptoms. Despite similar proportions of participants reporting symptoms in both groups (25.4% vs. 22.9%; difference: 2.5%), this was statistically highly significant (p < 0.0001). SARS-CoV-2 positive preschool children suffered more often from fatigue (RD 0.05), loss of smell (RD 0.01), loss of taste (RD 0.01) and muscle weakness (RD 0.01) than controls. SARS-CoV-2 positive school children suffered more often from loss of smell (RD 0.12), loss of taste (RD 0.10), fatigue (RD 0.05), respiratory problems (RD 0.03), dizziness (RD 0.02), muscle weakness (RD 0.02) and chest pain (RD 0.01) than controls. |
|
| Brackel 2021 [30] | December 2020 to February 2021 | The Nether-lands |
n = 89 children suspected of having Long COVID aged 2–18 years, reported by local paediatricians based at various hospitals across the country | Cross-sectional observational study | n.d. | Not provided | To determine the number of paediatric patients who have been referred to a specialist by a family doctor and are experiencing Long COVID symptoms | The most common complaints were fatigue (87%), dyspnoea (55%), concentration difficulties (45%) and headaches (38%). 36% of children had severe limitations in their daily activities. |
In a substantial proportion of patients, SARS-CoV-2 infection was not microbiologically confirmed. |
| Buonsenso 2021 [31] | March to October 2020 | Italy | n = 109 patients aged <18 years, at least 30 days after being diagnosed with SARS-CoV-2 infection (PCR confirmed) (on average 162.5 ± 113.7 days after infection) Questionnaire-based Included both patients with symptomatic and asymptomatic SARS-CoV-2 infection |
Cross-sectional study | n.d. | Not provided | To evaluate persistent symptoms after SARS-CoV-2 infection in paediatric patients | Overall, 41.8% of participants completely recovered, 35.7% reported 1–2 symptoms, 22.5% had more than 3 symptoms. 27.1% of participants (35 of 68 children) reported at least one persistent symptom for ≥120 days. Most common symptoms: Insomnia (18.6%), respiratory problems (14.7%), nasal congestion (12.4%), fatigue (10.8%), muscle (10.1%) and joint pain (6.9%), and impaired concentration (10.1%). |
2.3% of participants had MIS-C. Alternative diagnoses were not ruled out. No SARS-CoV-2 negative control group. |
| Buonsenso 2022 [32] | January 2020 to January 2021 | Mainly United Kingdom and USA | n = 510 participants aged 1–18 years Questionnaire-based survey (parent-led) |
Prospective survey | n.d. | Symptoms for >4 weeks after COVID-19 |
To evaluate prolonged symptoms after SARS-CoV-2 infection based on parental perception | Mean time of persistent symptoms after SARS-CoV-2: 8.2 months (standard deviation: 3.9) Most common symptoms: Tiredness and weakness (87.1%), fatigue (80.4%), headache (78.6%), abdominal pain (75.9%), muscle aches (68.4%), muscle and joint pain (60.6%), post-exertional malaise (53.7%), rash (52.4%), unexplained irritability (51.4%), dizziness (48.0%). Most common changes since SARS-CoV-2 infection: changes concerning energy levels (83.3%), mood (58.8%), sleep (56.3%), appetite (49.6%), lower levels of activity (90%), concentration difficulties (60.6%), memory problems (45.9%), difficulty doing everyday tasks (40%). |
In 41% of participants COVID-19 had not been confirmed by a test or medical professional. No SARS-CoV-2 negative control group. |
| Buonsenso 2022 [33] * | April 2020 to April 2021 | Italy | Larger cohort (n = 507) which included n = 179 children and n = 101 adults with PCR-confirmed SARS-CoV-2 infection, who had at least one follow-up at 1–3 months after infection n = 37 SARS-CoV-2 negative controls (children) n = 49 SARS-CoV-2 negative controls (adults) Assessment via phone call and face-to-face visits Follow-ups at 1–3 months and at 6–9 months |
Prospective cohort study | n.d. | Symptoms for >4 weeks after COVID-19 |
To describe and compare long-term symptoms after SARS-CoV-2 infection in adults and children living in the same households | A significantly higher number of adults reported at least one persistent symptom after COVID-19 at first follow-up compared with children (67%, 68/101 vs. 32%, 57/179; p < 0.001). Participants aged ≤18 years had a higher probability of full recovery in comparison to adults at both follow-ups at 1–3 months (p = 0.001) and 6–9 months (p = 0.01). 16.7% of children experienced co-existing symptoms from ≥ 2 symptom categories at 1–3 months follow-up, 3.3% reported symptoms from ≥ 3 categories. At 6–9 months follow-up, 5.1% of children reported symptoms from ≥ 2 and 1.4% from ≥ 3 categories. |
ISARIC Global COVID-19 follow-up protocol was used as a screening tool for persistent symptoms. Additional data were kindly provided by one of the authors |
| Buonsenso 2022 [34] | April 2020 to April 2022 | Italy | n = 679 PCR-confirmed participants aged 0–18 years Follow-up at 1–5, 6–9, and ≥12 months post-SARS-CoV-2 diagnosis Assessment via phone call, a survey, and face-to-face visits |
Prospective cohort study | Wild type virus (488/679 participants), Alpha, Delta, Omicron variants |
Delphi research definition Symptoms present for at least 4 weeks since the diagnosis of SARS-CoV-2 infection |
To assess the prevalence of persistent symptoms after SARS-CoV-2 and to evaluate risk factors, including virus variants | Most frequent persistent symptoms: fatigue (19%), headache (12%), insomnia (7.5%), muscle pain (6.9%), and confusion with concentration issues (6.8%). Overall improvement over time was reported: at the 1–5 months follow-up, 4% of parents reported ‘poor recovery’; 1.3% at 6–9 months; and 0.7% at ≥12 months follow-up. Patients not recovered by 6–9 months had a lower probability of recovery during the subsequent follow-up period. In total, 86% of participants described a full or almost complete recovery. |
ISARIC Global COVID-19 follow-up protocol for children was used. Symptom patterns according to virus variants were analysed. No SARS-CoV-2 negative control group. |
| Buonsenso 2023 [35] | n.d. | Italy | n = 1243 participants, median age 7.3 years (4.0–10.2). Follow-up at 3, 6, 12 months (18 months for pre-Omicron infections) |
Prospective study | Omicron (70.8%) Delta (19.9%), Alpha (6%), and wild-type (3.3%) variants |
Symptoms for >3 months after acute COVID-19 |
To evaluate the risk of persistent symptoms depending on SARS-CoV-2 variant |
Infection with pre-Omicron variants was associated with a significantly higher rate of persistent symptoms at 3 and 6 months. Highest odds ratios (ORs) were observed with the initial variants: wild-type SARS-CoV-2: 4.1 (2.2–7.7, p < 0.001) at 3 months and 8.6 (4.3–17.1, p < 0.001) at 6 months; Alpha variant: OR 4.4 (2.7–7.1, p < 0.001) at 3 months and 9.9 (5.8–16.8, p < 0.001) at 6 months. | |
| Chevinsky 2021 [36] * | March to June 2020 | United States | n = 305 inpatient patients aged <18 years n = 305 matched controls n = 2368 outpatient patients n = 2368 matched controls Healthcare database-based analysis |
Matched cohort study | n.d. | ‘Late conditions’ defined as conditions not previously recorded as underlying or acute COVID-19 conditions | To assess the type, association, and timing (1–4 months) of post-COVID conditions |
Children who previously had COVID-19 were not at a higher risk of experiencing post-COVID conditions compared with children who did not have COVID-19. | Analyses heavily focused on adult data. Study did not assess persisting symptoms (i.e., symptoms that started with COVID-19 and continued). |
| Funk 2022 [37] | March 2020 to January 2021 | 8 countries | n = 1884 PCR-confirmed SARS-CoV-2–positive children aged <18 years (1802 not hospitalised, 564 hospitalised) n = 1701 SARS-CoV-2–negative controls Follow-up 90–120 days after COVID-19 Participant recruitment in 39 paediatric emergency departments in 8 countries |
Prospective cohort study | n.d. | Persistent, new or returning symptoms >90 days after SARS-CoV-2 infection | To evaluate the prevalence of Post COVID-19 condition 90 days after an emergency department visit | Overall, 5.8% (95% CI, 4.8–7.0%) of SARS-CoV-2 positive participants had persistent symptoms. 9.8% (95% CI 7.4–13.0%) of hospitalised children vs. 4.6% (95% CI, 3.6–5.8%) of non-hospitalised children had persistent symptoms. Most common symptoms in the SARS-CoV-2–positive group: respiratory (e.g., cough, difficulty breathing, or shortness of breath; 2.0%) and systemic (e.g., fatigue or weakness; 1.8%). In the negative matched control group, 5.0% of hospitalised children and 2.7% of non-hospitalised children reported prolonged symptoms. Risk factors for PCC: Hospitalisation for ≥48 h, ≥4 acute symptoms, age ≥14 years. |
Comparison of hospitalised vs. non-hospitalised cases not provided in manuscript—calculated using data provided in manuscript: Fisher’s exact test p = 0.0001. No SARS-CoV-2 negative control group. |
| Guido 2022 [38] | February to November 2021 | Italy | n = 322 participants after SARS-CoV-2 infection aged between 1.5 and 17 years Evaluation at disease onset, after 1 month, and after 3–5 months |
Prospective study | n.d. | Persistent symptoms for more than 3 months after onset | To evaluate the presence of neurological symptoms and psychological effects | 22% of participants had persistent symptoms at 3–5 months. Most prevalent neurological symptoms: headache (7.5%), fatigue (6.8%), and anosmia (2.2%). Fewer symptoms were found in the group of 1.5–5-year-old patients compared with the 6–17-year-old patients. Other persistent symptoms: Cognitive, behavioural and mood problems (14%), sleep disturbances (13%), and changes in eating habits (10%). |
No SARS-CoV-2 negative control group. Unclear how SARS-CoV-2 infection was determined. |
| Jamaica Balderas 2023 [39] | July 2020 to December 2021 | Mexico | n = 215 patients <18 years with positive SARS-CoV-2 PCR test and/or IgG test Follow-up at 2, 4, 6, and 12 months |
Prospective study | n.d. | Persistent symptoms >12 weeks after acute SARS-CoV-2 infection |
To describe clinical experience with Long COVID patients in a paediatric centre | Persistent symptoms were observed in 32.6% of patients after 2, 9.3% after 4, and 2.3% after 6 months. Main persistent symptoms: dyspnoea, dry cough, runny nose and fatigue. |
8.4% of participants had MIS-C. No SARS-CoV-2 negative control group. |
| Katsuta 2023 [40] | February 2020 to April 2022 | Japan | n = 1697 SARS-CoV-2-positive patients <16 years |
Prospective study | pre-Delta, Delta, Omicron | Symptoms >28 days after SARS-CoV-2 infection | To evaluate persisting symptoms after SARS-CoV-2 infection | Prolonged symptoms were reported in 3.2% (n = 55). Common symptoms were dysosmia (1.1%), dysgeusia (1.0%), fever (0.8%), fatigue (0.7%), and cough (0.5%). Persistent symptoms were more likely to occur in patients who had fever or dysosmia at acute presentation. |
No SARS-CoV-2 negative control group. |
| Kikkenborg Berg 2022 [41] | January 2020 to July 2021 | Denmark | n = 6630 patients aged 15–18 years with confirmed SARS-CoV-2 infection n = 21,640 controls Questionnaire-based Paediatric Quality of Life (PedsQL) Children’s Somatic Symptoms Inventory-24 (CSSI-24) |
National cross-sectional study | n.d. | Persistent symptoms >2 months after SARS-CoV-2 infection |
To evaluate quality of life, psychological and social well-being, school absence during the pandemic, and long-term symptoms | Cases had higher odds of experiencing at least one Long COVID symptom lasting ≥2 months compared with the control group [3159 (61.9%) vs. 12,340 (57.0%), odds ratio 1.22 (95% CI 1.15–1.30); p < 0.0001]. Symptoms significantly more common in cases than controls: chest pain, headache, sore throat, dizziness, loss of appetite, trouble breathing, palpitations, and cough. Cases had better quality of life scores on PedsQL, as well as significantly higher physical, emotional, social, and school functioning mean scores. Cases also reported lower symptom scores in CSSI-24. |
|
| Kikkenborg Berg 2022 [42] | January 2020 to July 2021 | Denmark | n = 10,997 SARS-CoV-2-positive children aged 0–14 years n = 33,016 negative controls Questionnaire-based |
Cross-sectional study | Alpha, Delta variants | Persistent symptoms for >8 weeks after the positive SARS-CoV-2 test | To examine the prevalence, severity, and duration of persistent symptoms, as well as impact on quality of life, number of missed school or daycare days, and psychological and social effects after SARS-CoV-2 infection | In all age groups, cases had higher odds of experiencing at least one persistent symptom (for more than 3 months) than controls: 0–3 years age group (435 [36.4%] of 1194 vs. 872 [22.6%] of 3855; OR 1.94 [1.68–2.23], p < 0.0001) 4–11 years age group (1710 [34.0%] of 5023 vs. 5356 [29.2%] of 18,372; OR 1,28 [1.19–1.37], p < 0.0001) 12–14 years age group (1204 [42.1%] of 2857 vs. 3966 [36.8%] of 10,789; 1.26 [1.11–1.32], p < 0.0001). Symptoms significantly more prevalent in the case group included: fatigue, headache, dizziness, sore throat, muscle/joint pain, chest pain, trouble breathing, cough, and loss of appetite. There was a trend towards better quality-of-life scores in emotional and social functioning for cases compared with controls in older children. |
Similar rates of pre-existing co-morbidities in cases and controls. |
| Kompaniyets 2022 [43] | March 2020 to January 2022 | United States | n = 781,419 patients aged 0–17 years with SARS-CoV-2 infection n = 2,344,257 negative controls aged 0–17 years Analysis based on a large medical claims database Symptoms were classified by International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) |
Retrospective study | n.d. | Symptoms >4 weeks after SARS-CoV-2 infection | To assess persistent symptoms after SARS-CoV-2 infection | Patients with SARS-CoV-2 infection were less likely to experience the following symptoms/conditions: Respiratory symptoms (aHR = 0.91), sleeping disorders (0.91), neurological conditions (0.94), anxiety-related conditions (0.85), mood disorders (0.78), and muscle disorder (0.94). Patients with SARS-CoV-2 infection were more likely to experience the following symptoms/conditions: Smell and taste disturbances (aHR = 1.17), circulatory symptoms (1.07), malaise and fatigue (1.05), musculoskeletal pain (1.02), pulmonary embolism (2.01), myocarditis and cardiomyopathy (1.99), venous thromboembolic event (1.87), renal failure (1.32), type 1 diabetes (1.23), coagulation and haemorrhagic disorders (1.18), type 2 diabetes (1.17), and cardiac dysrhythmias (1.16). |
|
| Kuitunen 2022 [44] | January 2021 to September 2022 | Finland | n = 132 visits to general practitioners coded with a diagnosis of Long COVID in children aged 1–14 years. control group: 21,633 visits of controls aged 15–64 years aged for Long COVID. |
Retrospective register-based study | n.d. | not available | To analyse the incidence of formally-diagnosed Long COVID cases in Finnish children |
The visit rate due to Long COVID was very low in children compared to adults: age 1–6: 7.9 per 100,000 visits, age 7–14: 19.0 per 100,000 visits, age 15–64: 541.6 per 100,000 visits. |
Lack of clinical data. |
| Lorman 2023 [45] | March 2020 to June 2022 | United States | n = 14,399 patients <21 years, divided into 3 cohorts: n = 1309 post-acute Sequelae of SARS-CoV-2 (PASC) cases (using ICD-10 diagnosis U09.9) n = 6545 children with SARS-CoV-2 infection (PCR, antigen, or serology positive) n = 6545 children without SARS-CoV-2 infection |
Cohort study | Pre- and post-Omicron variants | NIH definition of PASC Persistent symptoms for >30 days after SARS-CoV-2 infection |
To identify clusters of PASC-associated diagnoses |
Significant increase was observed in multiple symptoms related to cardiovascular, respiratory, neurological, psychological, endocrine, gastrointestinal, and musculoskeletal systems among children with PASC. Typical symptoms in PASC cases (compared with both control groups) included dyspnoea, abnormalities in breathing, and malaise/fatigue. |
Study is based on Electronic Health Records from 9 different hospitals. n = 3806 (26.4%) patients were aged 16–20 years, including n = 346 PASC cases, n = 1730 SARS-CoV-2 negative, and n = 1730 SARS-CoV-2 positive patients. |
| Messiah 2022 [46] | March 2021 to January 2022 | United States | n = 312 children aged 0–19 years diagnosed with COVID-19 (n = 286) or MIS-C (n = 26) | Retrospective study | n.d. | NICE criteria | To assess the presence of acute (<30 days) and chronic (≥30, 60–120, and >120 days) long-term COVID symptoms |
26.9% of children with MIS-C and 15.3% without MIS-C reported persistent symptoms for ≥30 days. Females were almost twice as likely to report persistent symptoms compared to males. | No SARS-CoV-2 negative control group. Electronic Health Records based study. Additional data were kindly provided by one of the authors. |
| Merzon 2022 [47] | February 2020 to June 2021 | Israel | n = 20,601 patients aged 5–18 years after SARS-CoV-2 infection (PCR tested), including n = 65 patients with Long COVID Based on an online computerised Israeli database of patient demographics, medical visits, laboratory tests, hospitalisations, and prescriptions |
Population-based cross-sectional study | n.d. | Persistent symptoms ≥12 weeks after SARS-CoV-2 infection |
To identify demographic, clinical, and socioeconomic factors associated with Long COVID | 65 of 20,601 participants (0.32%) had a diagnosis of Long COVID Variables associated with Long COVID: hospitalisation due to COVID-19 infection (aOR 44.7), recurrent acute SARS-CoV-2 infection(s) within 180 days (aOR 43.7), symptomatic COVID-19 infection (aOR = 5.3), older age (aOR 1.4) Pre-existing conditions associated with Long COVID: ADHD (aOR 2.0), chronic allergic rhinitis (aOR = 2.7) and chronic urticaria (aOR 8.1). |
Small number of participants with Long COVID. No SARS-CoV-2 negative control group. Only included patients with formal diagnosis of Long COVID. Additional data were kindly provided by one of the authors. |
| Miller 2022 [48] | June 2020 to May 2021 | United Kingdom | n = 1062 patients ≤17 years with past or present evidence of SARS-CoV-2 infection n = 3970 patients without evidence of SARS-CoV-2 infection Questionnaire-based with weekly and monthly surveys |
Household-based community cohort study | n.d. | NICE guidelines Persistent symptoms lasting > 4 weeks |
To evaluate the prevalence of persistent symptoms after SARS-CoV-2 infection | 43 of 1062 (4.1%; 95% CI, 2.9–5.4%) patients with previous SARS-CoV-2 infection reported persistent symptoms. The prevalence of persisting symptoms in the whole cohort (including patients with or without evidence of SARS-CoV-2 infection) was 2.6% (129/5032 patients; 95% CI, 2.1–3.0%). |
Not all patients without evidence of SARS-CoV-2 infection had undergone laboratory testing. |
|
Mizrahi
2023 [49] * |
March 2020 to October 2021 | Israel | n = 118,308 SARS-CoV-2 positive patients ≤18 years n = 118,308 negative controls Electronic medical records from an Israeli nationwide healthcare organisation |
Retrospective nationwide cohort study | Wild-type, Alpha, Delta variants | Divided into early (30–180 days) and late (180–360 days) time periods after infection Defined as prolonged or new symptoms >4 weeks after acute onset |
To determine clinical sequelae of Long COVID during the first year after mild SARS-CoV-2 infection | Elevated risk according to age group: Age 0–4: Conjunctivitis (HR 1.18, 1.08–1.29) and dyspnoea (HR 1.22, 1.11–1.35) only during the early phase Age 5–11: Conjunctivitis (HR 1.24, 1.07–1.43) only during the early phase. Sore throat (HR 1.54, 1.20–1.97) only during the late phase Age 12–18 Anosmia and dysgeusia (HR 23.5, 5.48–100.86), dyspnoea (HR 1.7, 1.36–2.12) and weakness (HR 1.66, 1.41–1.96) only during the early phase In the entire cohort (including adults), there was a trend for anosmia/dysgeusia, dyspnoea, weakness, chest pain, and palpitations to decline over time. |
Only patients with mild disease. Study included additional adult cases and controls. Anosmia and dysgeusia were grouped together in the analysis. |
| Molteni 2021 [50] | September 2020 to January 2021 | United Kingdom | n = 1734 children with positive SARS-CoV-2 test aged 5–17 years n = 1734 negative SARS-CoV-2 matched controls |
Prospective cohort study | n.d. | NICE guidelines | To evaluate illness duration and symptoms of COVID-19 in children |
77 (4.4%) of 1734 children had symptoms for ≥ 28 days with low symptom burden (median 2 symptoms, IQR 1–4) in comparison to the first week of illness (median 6 symptoms, IQR 4–8). Most common persisting symptoms were fatigue, headache, and anosmia. 25 (1.8%) of 1379 children reported symptoms for ≥ 56 days. The most common symptoms in those 25 children over their entire illness were anosmia (84.0%), headache (80.0%), sore throat (80.0%), and fatigue (76.0%). Few children among the negative controls (0.9%) had symptoms for at least 28 days. |
|
| Morello 2023 [51] | February 2020 to October 2022 | Italy | n = 1243 patients aged 0–18 years after SARS-CoV-2 infection In-clinic follow-up at a post-COVID clinic at 3, 6, 12 and 18 months after onset |
Prospective cohort study | Wild-type virus, Alpha, Delta, Omicron variants The majority had infection with Omicron (70.8%). |
Delphi definition | To evaluate risk factors for Long COVID and recovery rates |
23% (294/1243) met the criteria for Long COVID at 3 months. Of 268 patients that had Long COVID at the 3-month and follow-up at 6 months 143 (53%) reported symptoms. At 12 months 38/167 (23%) and at 18 months 15/77 (19%) reported symptoms. Most common symptoms at 3 months: Fatigue (55.1%), exertional dyspnoea (26.2%), headache (23.5%) and gastrointestinal symptoms (19.0%), muscle pain (18.0%), concentration/memory problems (10.5%), joint pain (10.5%), and chest pain (9.9%). Risk factors for Long COVID: >10 years of age (OR 1.2; CI 1.2–1.3), presence of comorbidities (OR 1.7; CI 1.1–2.5) and hospitalisation during the acute phase (OR 4.8; CI 1.9–12.1). Reduced risk for Long COVID: infection with Omicron variant (OR 0.6; CI 0.5–0.8) and being asymptomatic during the acute phase of the infection (OR 0.5; CI 0.2–0.9). |
No SARS-CoV-2 negative control group. 89% of participants had only mild infection. Additional data were kindly provided by one of the authors |
| Nugawela 2022 [52] | January to March 2021 | United Kingdom | n = 3246 participants aged 11–17 years after SARS-CoV-2 infection n = 3893 negative matched controls |
Questionnaire-based cohort study | n.d. | Delphi definition | To create a predictive model for Long COVID symptoms in children and young people | 3 months after PCR test 25.2% (817/3246) of SARS-CoV-2 positive patients and 18.5% (719/3893) of the control group experienced ≥ 1 impairing ongoing symptoms (p < 0.001; calculated based on data provided in the manuscript) A risk prediction equation to identify those at highest risk of Long COVID 3 months after SARS-CoV-2 infection was established. |
Data from the children and young people with Long COVID (CLoCk) study was used. |
| Osmanov 2022 [53] | April to August 2020 | Russia | n = 518 hospitalised patients ≤18 years after PCR-confirmed SARS-CoV-2 infection Median follow-up time since hospital discharge: 256 days |
Cross-sectional cohort study | Wild-type virus | Persistent symptoms >5 months | To evaluate long-term outcomes and to identify risk factors in children previously hospitalised after SARS-CoV-2 infection | 126 patients (24.3%) experienced persistent symptoms at follow-up. 44 patients (8.4%) reported symptoms in ≥2 categories. Most common symptoms: Fatigue (n = 53, 10.7%), sleep disorders (n = 36, 6.9%), and sensory problems (n = 29, 5.6%). Risk factors for Long COVID: Older age, with 6–11 years (OR 2.7 (95% CI 1.4 to 5.8) and 12–18 years (OR 2.7, 95% CI 1.4 to 5.4) and history of allergic diseases (OR 1.7, 95% CI 1.04 to 2.7). |
ISARIC Global follow-up protocol was used. Only hospitalised patients included. No SARS-CoV-2 negative control group. |
| Palacios 2022 [54] | February to December 2021 | United States | n = 82 adolescents with an average age of 15.2 years Evaluation at median time of 3.5 months after SARS-CoV-2 infection, 49% had a follow-up 2–3 months later |
Single- center, retrospective cohort study |
n.d. | Persistent symptoms for more than 4 weeks after infection | To evaluate persistent pulmonary abnormalities after COVID-19 |
80% of participants reported ≥2 symptoms (cough, chest pain, dyspnoea at rest or during exercise), 67% of participants followed up at about 6.5 months post-infection had persisting exertional dyspnoea. 77% of participants had normal spirometry, 17% (n = 14) had obstructive deficits, and 6.1% (n = 5) had restrictive deficits. Normal results were shown on plethysmography or diffusion capacity. |
No SARS-CoV-2 negative control group. |
| Pazukhina 2022 [55] | April to August 2020 | Russia | n = 360 previously hospitalised children (median age 9.5 years) with confirmed SARS-CoV-2 infection Two follow-up telephone interviews at 6 and 12 months after discharge |
Prospective cohort study | n.d. | WHO definition | To assess prevalence and risk factors of Post Covid-19 Condition |
At least one persistent symptom was present in 20% (95% CI 16–24) of children at 6 months, decreasing to 11% (95% CI 8–14) at 12 months. Most common symptoms at 6 months: Fatigue 9%, dermatological 5%, neurocognitive 4% and sleep-related symptoms 4%. At 12 months: decrease of symptoms to 4%, 2%, 2%, and 1% was observed, respectively. Risk factors associated with post COVID condition: neurological comorbidities both at 6 months (OR 4.4, 1.4 to 15.7) and 12 months (OR 9.0 2.6 to 34.8), allergic respiratory diseases at 12 months (OR 2.7, 1.04 to 6.5). |
No SARS-CoV-2 negative control group. |
| Pinto Pereira 2023 [56] | September 2020 to March 2021 | England | n = 6407 SARS-CoV-2 positive patients aged 11–17 years n = 6542 SARS-CoV-2 negative controls Questionnaire-based study 6 months after acute illness |
National cohort study | n.d. | Delphi definition | To evaluate physical and mental health 6 months after SARS-CoV-2 infection |
24.5% of SARS-CoV-2 positive patients and 17.8% of negative controls had Long COVID symptoms at 6 months after infection. Common symptoms in both groups: Tiredness, shortness of breath, and headaches. |
|
| Pinto Pereira 2023 [57] | September 2020 to March 2021 | England | n = 2909 SARS-CoV-2 positive patients aged 11–17 years n = 2177 SARS-CoV-2 negative controls Questionnaire based follow-up after 6 and 12 months |
Prospective study | Wild-type, Alpha (B.1.1.7) variants | Delphi research definition | To assess health and well-being 6 and 12 months after SARS-CoV-2 infection |
Prevalence of Long COVID at 6 and 12 months: SARS-CoV-2 positive group: 6 m: 748/2909 (25.7%) 12 m: 785/2909 (27.0%). SARS-CoV-2 negative group: 6 m: 362/2177 = (16.6%) 12 m: 458/2177 = (21.0%). |
Additional data were kindly provided by the first author. |
|
Roessler
2022 [58] * |
January 2019 to December 2020 | Germany | n = 11,950 patients aged 0–17 years with COVID-19 n = 59,750 matched control group Mean follow-up time: 236 days after acute illness |
Retrospective matched cohort study based on health insurance data |
Pre-Omicron variants | WHO definition, but symptoms >3 months after diagnosis of COVID-19 |
To evaluate morbidity after COVID-19 in children and adolescents | Incidence Rate Ratios (IRR) of documented health-related problems was significantly higher in the COVID-19 group (IRR: 1.3, 95% CI: 1.25-1.35, p < 0.01). Specific outcomes with the highest IRR were malaise/fatigue/exhaustion (IRR 2.3), cough (IRR 1.7), throat/chest pain (1.7). |
Data from German statutory health insurance organisations. |
| Roge 2021 [59] | July 2020 to April 2021 | Latvia | n = 236 patients with COVID-19 aged 1 month to 18 years n = 142 SARS-CoV-2 negative controls with other community-acquired Infections |
Ambi-directional cohort study | n.d. | NICE criteria | To evaluate ongoing symptoms 1–6 months after SARS-CoV-2 infection Median follow-up time after COVID-19: 73.5 days (IQR 43–110 days), 69 days in the control group (IQR 58–84 days) |
44.5% (n = 105) of SARS-CoV2 positive patients reported persistent symptoms 12 weeks after infection. Most common symptoms: irritability (27.6%, n = 29), changes in mood (26.7%, n = 28), and fatigue (19.2%, n = 20). In comparison to the control group, persistent symptoms such as fever [adjusted Odds Ratio (ORa) 4.0, 95% CI: 1.4–11.6; p = 0.01], fatigue (ORa 8.7, 95% CI: 2.5–29.9; p = 0.001), rhinorrhea (ORa 2.6, 95% CI: 1.3–5.4; p = 0.008) anosmia/dysgeusia (ORa 11.2, 95% CI: 1.4–89.1; p = 0.02), headaches (ORa 12.9, 95% CI: 1.7–99.6; p = 0.01), nocturnal sweating (ORa 16.7, 95% CI: 2.1–130.4; p = 0.007) were significantly associated with SARS-CoV-2 infection. Cognitive difficulties (concentration, memory, attention, mood changes, irritability and anxiety/depression) were also significantly more common in cases than controls. |
Control group consisted of patients with other community-aquired infections. |
| Sakurada 2023 [60] * | February 2021 to October 2022 | Japan | n = 54 patients diagnosed with Long COVID aged 11–18 years n = 398 patients diagnosed with Long COVID aged >19 years |
Retrospective observational study | Alpha, Delta, Omicron variants | Symptoms >4 weeks after onset of SARS-CoV-2 infection |
To evaluate clinical characteristics of Long COVID in teenagers compared with adults |
In both groups the most frequent complaints were fatigue (teenagers: 55.6% vs. adults: 61.1%; p = 0.44) and headache (35.2% vs. 21.9%; p = 0.03). Other common symptoms included dyosmia, dysgeusia, insomnia, dyspnoea and hair loss, but no significant differences between teenagers and adults were detected. |
No SARS-CoV-2 negative control group. |
| Seery 2023 [61] | June 2020 to June 2021 | Argentina | n = 639 patients 1–17 years old with confirmed SARS-CoV-2 infection n = 577 SARS-CoV-2 negative controls Parent questionnaire 6 months after testing |
Observational study | Pre-Omicron variants | WHO criteria Symptoms >3 months after SARS-CoV-2 infection |
To evaluate long-term symptoms of SARS-CoV-2 and associated risk factors | Significantly more patients with previous infection had at least one symptom ≥3 months compared with the control group (34% vs. 13%, p < 0.0001). There was a 3 to 7-fold increased risk of headache, dizziness, loss of taste, dyspnoea, cough, fatigue, muscle pain and weight loss in the subgroup that had experienced SARS-CoV-2 infection. Risk factors for Long COVID were older age, comorbidities and symptomatic infection. |
|
| Sorensen 2022 [62] | September 2020 to April 2021 |
Denmark | PCR confirmed SARS-CoV-2 cases aged 15–19 years: ♀ n = 1512 ♂ n = 838 SARS-CoV-2 negative controls: ♀ n = 2163 ♂ n = 1018 |
Prospective questionnaire -based study | Wild type, Alpha | WHO definition | To evaluate the risk differences between SARS-CoV-2 positive participants and negative controls for persistent symptoms 6–12 months after SARS-CoV-2 infection |
There was no risk difference between cases and controls regarding PTSD, anxiety, or depression. There was an increased risk difference in cases regarding chronic fatigue (in ♀ and ♂) and fibromyalgia (in ♀). Dysosmia, dygeusia, reduced appetite, and reduced strength were more common in cases than in controls (in ♀ and ♂), dyspnoe, chest pain, dizziness, fatigue and headache were more common in cases than in controls in ♀ only. Difficulties concentrating (♀ 33% vs. 9.6%, RD 25.3; ♂ 17.1% vs. 5.1%, RD 13.4), memory issues (♀ 26% vs. 5.5%, RD 22.6; ♂ 13.7% vs. 3.6%, RD 11.3), mental exhaustion (♀ 46.8% vs. 18.9%, RD 29.3; ♂ 24.3% vs. 9.8%, RD 15.8), physical exhaustion (♀ 46.4% vs. 12.2%, RD 36.3; ♂ 23.2% vs. 6.5%, RD 37.9), and sleeping problems (♀ 23.9% vs. 11.3%, RD 13.6; ♂ 15.6% vs. 7.1%, RD 9.2) were more common in cases than in controls. |
Figures based on supplementary data file of the original manuscript and additional data kindly provided by the author. |
| Stephenson 2022 [63] | January to March 2021 | United Kingdom | n = 3065 SARS-CoV-2 positive adolescents aged 11–17 years n = 3739 matched negative controls |
Longitudinal cohort study |
Mainly Alpha | Persistent symptoms for more than 3 months after SARS-CoV-2 infection |
To evaluate the incidence and clinical phenotype of Long COVID | At 3 months 2038 (66.5%) positive participants and 1993 (53.3%) negative controls had any symptoms, and 928 (30.3%) from the positive group and 603 (16.2%) from the control group had three or more symptoms. At 3 months the most common symptoms in the SARS-CoV-2 positive group vs. the control group were: tiredness (39.0% vs. 24.4%), shortness of breath (23.4% vs. 10.4%) and headaches (23.2% vs. 14.2%). All three comparisons were statistically highly significant (p < 0.0001). |
|
| Stephenson 2023 [64] | January to March 2021 | United Kingdom | n = 1658 SARS-CoV-2 positive 11–17 year old patients (PCR confirmed) n = 1737 SARS-CoV-2 negative controls Follow-up online questionnaire 3 and 6 months after PCR test |
Prospective study | n.d. | No clear definition provided | Evaluation of ongoing symptoms after SARS-CoV-2 infection | There were 35.9% SARS-CoV-2 patients with at least 1 symptom at baseline, compared with 67.8% at 3 and 56.6% at 6 months. In the control group 9.2% had at least 1 symptom at baseline, 53.3% at 3 and 35.3% at 6 months. The 11 most common symptoms (>10%) in SARS-CoV-2 patients were: Fever, chills, headache, loss of smell, muscle pain, persistent cough, sore throat, skipping meals, shortness of breath, tiredness, and dizziness. After 3 months, prevalence of those symptoms was reduced and a smaller decline was observed after 6 months. The same symptoms and trends were observed among the control group at lower prevalence. New symptoms were reported after 6 months in both groups. |
Data from national matched cohort study (The CLoCk). |
| Valenzuela 2022 [65] | March 2020 to December 2021 |
Chile | SARS-CoV-2 positive (PCR-tested) hospitalised patients at 3 tertiary hospitals n = 216 hospitalised patients n = 67 (31%) of those were obese |
Observational study | Alpha, Gamma, Lambda and Delta variants | Symptoms >4 weeks after onset of symptoms | Association of obesity and post-acute sequelae of SARS-CoV-2 infection |
At the 6 months follow-up obesity was associated with dyspnoea (aOR 9.91, 95% CI 1.92–51.10) and muscle weakness (aOR 20.04, 95% CI 2.50–160.65). There was a significant association between obesity and muscle weakness in all age groups, but the association between obesity and dyspnoea was only significant in patients < 12 years. |
Obesity was associated with ICU admission, oxygen requirement, non-invasive ventilatory support, superinfections and bacterial pneumonia. |
| Warren-Gash 2023 [66] | November 2021 to April 2022 | United Kingdom | n = 7797 children (SARS-CoV-2 positive and negative) Data from COVID-19 School Infection Survey (SIS) 3 survey rounds at 173 schools Round 1: Nov.–Dec. 2021 Round 2: Jan.–Feb. 2022 Round 3: Mar.–Apr. 2022 Questionnaire-based in round 1 and 3 |
Prospective observational study | Pre- and during Omicron | Delphi research definition Symptoms lasting >12 weeks after onset of SARS-CoV-2 infection |
To assess the prevalence of Long COVID comparing persisting symptoms between SARS-CoV-2 positive and negative children |
Symptoms that were significantly more common in SARS-CoV-2 positive patients than the control group comprised: 4–11 years: loss of smell/taste and cardiovascular 11–16 years: loss of smell/taste, cardiovascular and systemic symptoms (fever, chills, weakness or tiredness) 16–18 years: loss of smell/taste and pulmonary. |
Control group comprised of children without a history of SARS-CoV-2 or without known positive test result; prior infection not excluded via serology. |
| Pulmonary function/inflammatory markers | |||||||||
|
Sommen
2023 [67] * |
December 2020 to May 2021 | Norway | n = 405 SARS-CoV-2 positive participants (aged 12–25 years; median: 18 years) n = 111 negative controls Baseline and follow-up at 6 months after mild SARS-CoV-2 infection |
Prospective study | Alpha (B1.1.7.) variant | WHO definition | Investigation of immunological blood markers and pulmonary function after SARS-CoV-2 infection |
Elevated levels of chemokines/cytokines (eotaxin, MCP-1, and IP-10) were detected 6 months after mild SARS-CoV-2 infection. No difference between patients with Long COVID and those without in any of the immunological parameters investigated. No difference in pulmonary function between the SARS-CoV-2 positive and negative groups regardless of long-lasting symptoms. |
Only included patients with mild SARS-CoV-2. Study included adults; no age breakdown provided. |
| Long COVID and mental health | |||||||||
| Akçay 2022 [68] | April 2020 to February 2021 | Turkey | n = 74 patients aged 11–17 years after SARS-CoV-2 infection Revised Children’s Anxiety and Depression Scale (RCADS) and UCLA-loneliness scale were used. Baseline inflammatory markers at acute phase of infection |
Retrospective study | n.d. | Not provided | To investigate how baseline inflammation levels, internalising symptoms, and feelings of loneliness are related in SARS-CoV-2 survivors |
Only a weak association between baseline C-reactive protein levels and major depressive disorder was found (r = 0.258, p = 0.027). Higher levels of anxiety in the patient or the parent were associated with a higher risk of developing depression, as was loneliness in the patient. |
No SARS-CoV-2 negative control group. |
| Blankenburg 2022 [69] | March to April 2021 | Germany | n = 188 seropositive students (median age 15 years) n = 1365 seronegative controls |
Cross-sectional survey (school-based) | n.d. | Persisting symptom >12 weeks after acute SARS-CoV-2 infection |
Assessing certain neurocognitive, pain, and mood symptoms | High rates of neurocognitive, pain and mood symptoms were observed in both groups. Female students reported a consistently higher prevalence of neurocognitive, pain and mood symptoms. Only one statistically significant difference was detected: seropositive students felt less sadness (p < 0.05). |
|
| Shachar-Lavie 2023 [70] | November 2020 to August 2021 | Israel | n = 103 patients with Long COVID (serologically or PCR confirmed) n = 113 uninfected healthy children aged 4–18 years in the control group Parent questionnaire-based and structured interviews |
Case–control study | n.d. | Symptoms >4 weeks after SARS-CoV-2 infection |
To examine the consequences of Long COVID on children’s mental health | In Long COVID patients, there was a significantly higher prevalence of memory difficulties. No group differences were found in other functional aspects (connection with friends and engagement in physical activities), concentration impairment, as well as emotional and behavioural problems. |
|
| Cardiac impact | |||||||||
| Erol 2021 [71] | March to June 2021 | Turkey | n = 121 SARS-CoV-2 positive patients aged 0–18 years (positive PCR or positive history) n = 95 controls without known contact with COVID-19 cases Evaluation of blood pressure, electrocardiography, and echocardiography results |
n.d. | n.d. | No clear definition of Long COVID Included patients that had SARS-CoV-2 infection >1 month and <1 year ago |
To evaluate persistent symptoms after SARS-CoV-2 infection in relation to cardiovascular health | 37.2% (n = 45) of SARS-CoV-2 positive patients had persistent symptoms during the study period. The most common persistent symptoms were dizziness ± syncope (15.6%) and palpitations ± chest pain (11.1%). chest and back ache (51.1%). Significant differences between the study and control group were found in systolic blood pressure values and echocardiographic parameters (left ventricular ejection fraction, relative wall thickness, and tricuspid annular plane systolic excursion). No significant differences in heart rates in ECG, PR intervals, and QTc values between both groups. |
Not all cases were microbiologically confirmed. Prior SARS-CoV-2 infection in controls not excluded via serology. Only the blood pressure values of patients >2 years were evaluated. |
| Sabatino 2022 [72] | February 2020 to December 2021 | Italy | n = 157 SARS-CoV-2 positive patients aged 0–18 years (microbiologically confirmed) n = 107 healthy patients in the control group Three follow-up groups: <180 days, 180–240 days, >240 days Performing of transthoracic echocardiogram and speckle-tracking echocardiography |
Single-centre observational prospective study | n.d. | No definition of Long COVID provided | To evaluate cardiac mechanics in previously healthy patients after asymptomatic or mild SARS-CoV-2 infection | A significant reduction in left ventricular global longitudinal strain in SARS-CoV-2 group compared to controls (SARS-CoV-2: −20.5 ± 2.9%; controls: −21.8 ± 1.7%; p < 0.001). No significant differences between the three follow-up groups were identified. |
Only patients with asymptomatic or mild disease (WHO stages 0 or 1) were included. No association between virus variants and cardiac findings. |
| Anosmia/Ageusia | |||||||||
| Mariani 2023 [73] | Beginning of the pandemic until October 2022 | Italy | n = 1250 patients aged <19 years referred to an outpatient clinic after microbiologically confirmed SARS-CoV-2 infection Follow-up at 3, 6, 12, and 18 months after infection |
Retrospective study | Wild type, Alpha, Delta, and Omicron variants |
Symptoms for >12 weeks after confirmed SARS-CoV-2 infection that cannot be explained otherwise | To evaluate risk factors for persistent anosmia and dysgeusia after SARS-CoV-2 infection Also, to evaluate SARS-CoV-2 variants, hospitalisation, vaccination, and olfactory/gustative dysfunction during the acute phase of infection |
During the acute phase of infection, 5.1% of all patients had anosmia and 4.2% had dysgeusia. At 3 months (n = 1250) 1% had anosmia; 1% dysgeusia At 6 months (n = 1224) 0.6% had anosmia; 0.6% dysgeusia At 12 months (n = 181) 1.7% had anosmia; 1.1% dysgeusia At 18 months (n = 87) 2 (2.3%) had anosmia; only 1 (1.1%) dysgeusia. Risk factors for persistent anosmia and dysgeusia were onset during during the acute phase of SARS-CoV-2, and Infection/illness due to a pre-Omicron variant. |
Impact of virus variants and vaccination status included in analysis. No significant association between vaccination status and persistence of dysgeusia and anosmia. Onlyfew patients were assessed at 18 months. |
| Namazova-Baranova 2022 [74] | n.d. | Russia | n = 61 patients aged 6–18 years after SARS-CoV-2 infection n = 20 controls without previous SARS-CoV-2 infection Examination at 6–8 weeks after recovery and after 1 year Olfactory and gustatory sensitivity test scores were used, the three-component olfactory test and a parent questionnaire |
Prospective study | n.d. | Not provided | To evaluate smell and taste after SARS-CoV-2 infection | Compared with controls, a reduction in the ability to smell and taste was observed in the SARS-CoV-2 group. Olfactory sensitivity in participants who had recovered from SARS-CoV-2 returned to normal levels after 6–12 months. |
Small sample size; very small cohort at 1 year (n=21). Control group was also small. Previous SARS-CoV-2 infection not excluded in control group (e.g. by serology). |
| Rusetsky 2021 [75] | April and May 2020 | Russia | n = 79 hospitalised patients aged 6–17 years with PCR-confirmed SARS-CoV-2 infection Follow-up at day 5 and day 60 Evaluation based on the SNOT-22 standardised questionnaire, psychophysical olfactory test, and telephone survey |
Prospective cross-sectional study | n.d. | Not provided | To evaluate the olfactory status after acute SARS-CoV-2 infection |
At day 0 (D0) 54/79 (68.4%) participants had olfactory impairment, which declined to 41/79 (51.9%) at D5. At D60 all participants had fully recovered (n = 72; 7 lost to follow-up). In 3 patients, recovery only occurred after D30. | Small sample size. No SARS-CoV-2 negative control group. Patients with a “severe need for oxygen support” were excluded. |
* Also includes adult patients; Abbreviations: ADHD = attention deficit hyperactivity disorder; adjusted hazard ratio = aHR, adjusted odds ratio = aOR, D = day; n.d. = no data; MIS-C = Multisystem Inflammatory Syndrome in Children; NIHR = UK National Institute for Health Research; PASC = post-acute sequelae of SARS-CoV-2 infection; RD = risk difference; WHO = World Health Organization.