A Prospective Study of Clinical, Epidemiological and Serologic Status Features in a Paediatric Pcr Sars-Cov-2 Positive Population

Background:Although most cases of SARS-CoV-2 infection in pediatric population are asymptomatic or mild, severe cases may occur in a small percentage. Unlike other respiratory infections, children usually develop it from infected adults. Percentage of seroconversión and outcome of antibodies after infection anti-SAR-CoV-2 in children are still poorly understood and may be different from adults. The first aim was to describe clinical and epidemiological characteristics of pediatric patients diagnosed of SARS-CoV-2 infection in the second epidemic wave in two tertiary hospitals in Madrid, Spain and to determine the proportion of seronegative by comparing 3 serological techniques. As secondary aim it was proposed to determine the proportion of seronegative by comparing 3 serological techniques, seroconversion associated variables and the way of infection among the family members. Methods:Multicenter prospective observational study in two university hospitals of the Community of Madrid, between September and November 2020, of COVID-19 infection confirmed by PCR in the Emergency Department. A retrospective data collection was performed at 4-8 weeks after diagnosis on an outpatient basis, using a clinical-epidemiological questionnaire. At this time blood samples were collected to analyse the humoral response by 3 different serological assays.The quantitative variables are expressed as medians (interquartile range (IQR) 25-75).Univariate analysis of possible factors associated with seropositivity absence was performed.Results: One hundred and eleven patients (58 girls) were included with a median days of 37 (IQR: 34-44) between diagnosis and serologic test performed.Median age was 88 (IQR: 24-149) months. Parents were from abroad in 62 cases (50% from South and Central America).Ninety eight children were symptomatic, 17 children were diagnosed by epidemiological screening, 4 of whom subsequently developed symptoms.Eight of them needing admission with a median length of stay 2 days (IQR: 2-4), none of them in PICU.Underlying conditions were found in 33 patients, mainly recurrent bronchitis.Most frequent symptoms (70%) were low-grade fever (37-38ºC) or fever (≥ 38ºC), rhinorrhea 44%, cough 31.5%, headache 29.7%, weakness 27%, diarrhea 19.8%, abdominal pain and vomiting 26%, anosmia 16.2% (median 10 days; IQR: 6-30). Infection was interpreted as a secondary case in 56 patients, being a relative the index case in 96.4%. Seronegativity was observed in 19 patients in any of the 3 serological techniques (17.1%; 95% CI: 10.6-25.4), this proportion was higher among children aged 2-to 10-year-old age (16 of 45; 35%, p Conclusions: Our results confirm the mild clinical picture in children during the second epidemic wave, and that in most cases, children are not the index case in the family. Likewise, in children the proportion in whom seroconversion is not detected is high, and seems higher than that reported in adults. In our series, an association of seronegativity was seen in the 2 to 10 year-old age group and when there was no documentation of COVID-19 in any household contact.