Figure 3
Clinical Manifestations
Fever was found to be the most frequent symptom with 64% (CI 95% 54%-72%), I2 88.18% and p<0.001, followed by cough 42% (CI 95% 37%-48%) I2 59.54% and p<0.001, vomit 31% (CI 95% 17-47%), I294.42% p<0.001 and diarrhea 28% (CI 95% 17%-47%) I2 92.67%, p<0.001. Figure 4.Abdominal pain and constipation 27%(CI 95% 12%-45%) I2 of 95.32% p<0.001, rhinorrhea 19% (CI 95% 12%-28%), I2 79.74%% p<0.001,  fatigue and myalgia 15% (CI 95% 5%-27%)  I2=93.03% p<0.001, tachypnea 13% (CI 95% 0%-45%) I2= 88.63% p<0.001, and less common symptoms were sore throat 10%, (CI 95% 4%-16%) I2 82.42% p<0.001, headache 10% (CI95% 4%-19%) I2 83.30% and p<0.001 and finally expectoration with a frequency of  9% (CI95% 2%-20%) I2 96.65%, p<0.001. Meta-analysis of other symptoms are shown in Supplementary Material .
Image and laboratory findings
The most important laboratory alterations were: lymphopenia 19.55% (124/634) [18,21,22,25,26,28-30,34-36,40,43-47,52,54,58,60,61], lymphocytosis 18.29% (86/470) [21,22,25,26,29,30,33-36,40,43,45,47,52,58,59], neutrophilia 17.84% (58/325) [18,21,22,25,33-36,40,44,45,47,58,62] leucopenia 17.19%  ( 87/506) [24,25,28,29,31,32,33,36,38,43,46,48-50,57,61] and leukocytosis 16.35% (78/477) [21,22,25,26,29,30,32-35,40,43,47,52,58,62]. Pro-inflammatory biomarkers: C-reactive protein increased in 28.55% (205/718) of patients [21-26,28-35,40,43-46,48,52,54,56,58,60-62] and high level of procalcitonin was presented in 18.26% (76/416) of cases. [21,23,24,26,28-30,33,34,40,46,47,54,60-62]. Supplementary Material .
Other laboratory findings were: D-dimer was increased in 42.85% (75/175) of patients [21,23,25,28,29,33,36,39,44,47,61,62], alanine- aminotransferase were increased in 22.10% (84/380) [21,25,26,28,29,33-36,40,44,45,47,52,54,62] and  high dehydrogenase lactic were presented 21.56% (55/255) of cases [21,25,27,29,33,34,36,40,45-47,52,61]. Patients who reported laboratory results were hospitalized therefore we cannot correlate the laboratory findings with illness severity. Supplementary Material .
In respect to image findings a total of 39.61% (353/891) cases had abnormalities in chest CT scan [21-30,33-37,40,43-47,51,52,54,56,57,58,60,62] and 51.10 % (162/317) in chest radiography [18,21-24,29,40,44,52,56-58,62] characterized primarily by ground-glass opacities 35.43% (208/587) [17,21-26,28-30,35,37,40,43,45-47,52,54,60,62]. In some articles the imaging studies were taken from all hospitalized patients, including asymptomatic, in others studies only from those with more severe symptoms.
Bilateral compromise was seen in 34.82% cases 156/448 [18,22,23,27,29,30,34,35,37,40,43-46,54,60] and 25.58% (98/383) cases had unilateral involvement [21,26,27,29,30,33-35,40,43-46,54].Supplementary Material .
 Management
Patients were treated with interferon, antivirals (lopinavir-ritonavir), steroids and immunoglobulin. So far, we cannot evaluate effectivity of treatments on the outcomes because all studies are observational and not reported individual or aggregate outcomes.
Complications and outcomes
Coinfection with other pathogen was seen in16.77% (104/620) of cases [18,21,22,26,27,30,35,38,43,45,49,56,58,60], the most reported wasMycoplasma pneumoniae in 21.95% (72/328) cases [26,27,30,34,35,43,45], Influenza A & B virus and syncytial respiratory virus were encountered in 4, 7 and 8 patients, respectively [21,26,30,49,56] Also, Sun D et al. reported 2 patients who developed sepsis. All patients with co-infection were hospitalized, and a total of 10.34% (129/1247) children admitted to the pediatric intensive care unit. [17,18,21,27,35,48-50,56,57,58,60,62], 11.56% (48/415) received mechanical ventilation. In five studies reported deaths, the mortality rate was 0.16% (8/4871) [17,31,39,50,60]
PIMS-ST in COVID-19.
Of the 44 studies included in this systematic review, 5 of them specifically described several patients with Kawasaki disease and/or the presence of PIMS-TS in hospitalized patients with history of SARS-CoV-2 infection. [21,22,47,51,65]. In the largest case series published by Whitaker et al. [17 ] they included 58 children, with a median age of 9y, met the criteria for PIMS-TS divided in three patterns; 23 patients presented with fever and elevated pro-inflammatory markers such as RCP, 13 met criteria for complete KD , and 29 presented a toxic shock due to KD or myocardial damage. All patients had fever, 31 developed abdominal pain, 15 headache, 6 sore-throat, 26 patients presented conjunctivitis, 17 had changes in mucus membranes, 9 lymphadenopathy and 9 had swollen extremities. Admission to PICU was required in 29 patients and 25 required mechanical ventilation. All of them had elevated RCP. One patient died. The complete information about these 5 studies is available in Supplementary Material. The most relevant in all studies is the severity of illness, 65.5 % of children were admitted to PICU and one dead.