Introduction: Respiratory viruses are among the leading causes of disease and death among children. Co-circulation of influenza and SARS-CoV2 can lead to diagnostic and management difficulties given the similarities the clinical picture. Methods: This is a cohort of all children hospitalized with SARS-CoV2 infection from March to September 3rd 2020, and all children admitted with influenza throughout five flu-seasons (2013-2018) at a pediatric referral hospital. Patients with influenza were identified from the clinical laboratory database. All hospitalized patients with confirmed SARS-CoV2 infection were followed-up prospectively. Results: A total of 295 patients with influenza and 133 with SARS-CoV2 infection were included. The median age was 3.7 years for influenza and 5.3 years for SARS-CoV2. Comorbidities were frequent in both groups, but they were more common in patients with influenza (96.6% vs 82.7%, p <0.001). Fever and cough were the most common clinical manifestations in both groups. Rhinorrhea was present in more than half of children with influenza but was infrequent in those with COVID-19 (53.6 vs 5.8%, p<0.001). Overall, 6.4% percent of patients with influenza and 7.5% percent of patients with SARS-CoV2 infection died. In-hospital mortality and the need for mechanical ventilation among symptomatic patients were similar between groups in the multivariate analysis. Conclusions: Influenza and COVID-19 have a similar picture in pediatric patients, which makes diagnostic testing necessary for adequate diagnosis and management. Even though most cases of COVID-19 in children are asymptomatic or mild, the risk of death among hospitalized patients with comorbidities may be substantial, especially among infants.

LETTER TO THE EDITOR

Background Pediatric patients represent approximately 2% of overall confirmed cases of COVID-19. Illness severity and symptoms differ from adults. Most cases in children are mild but various studies have reported severe and critical cases as well as fatal outcomes. Methods A systematic review and meta-analysis of the available literature was performed. Frequencies were used for reporting categorical variables. Meta-analyses were performed using the binary random effects model for symptoms frequencies in children and illness severity. Results We found 44 studies (n=6026), 38 were used for quantitative synthesis to estimate the frequency of symptoms in the pediatric population with Covid-19 and illness severity, 44 were used for qualitative synthesis. The most common symptoms were fever 64% (CI 95% 54-72%), cough 42% (CI 95% 37-48%) and gastrointestinal symptoms like vomit 31% (CI 95% 17-47%) and diarrhea 28% (CI 95% 17-40%). For illness severity 2% (CI 95%0-5%) were severe and 3% (CI 95% 1-6%) were critical. Children <1-year-old had the higher odds of severe/critical cases with an OR of 2.07 (IC95% 1.40-3.05). All patients were hospitalized, and a total of 10.34% children admitted to PICU. The mortality rate was 0.16% (8/487). A total of 141 patients developed PIMS-TS and only one died. Conclusions: Most cases in children were non-severe, nevertheless children less than 1 year had the higher risk of severe/critical cases. Symptoms frequencies encountered from major to minor were fever, cough and gastrointestinal symptoms. More testing in children should be done in order to understand transmission characteristics in the pediatric population.