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Archivos de Pediatría del Uruguay

Print version ISSN 0004-0584On-line version ISSN 1688-1249


AMAYA, Gabriela; SANTORO, Anabella; FERNANDEZ, Karina  and  DEWAELE, Rita. Related PCR positivity factors for SARS-CoV-2 in children under 15 years of age. Arch. Pediatr. Urug. [online]. 2022, vol.93, n.nspe2, e226.  Epub Dec 01, 2022. ISSN 0004-0584.


the SARS-CoV-2 infection has shown a lower percentage in children compared to the global incidence of patients infected by this virus. The Polymerase Chain Reaction (PCR) test for SARS-CoV-2 in a sample of nasopharyngeal secretions is considered the reference standard test, and it has shown higher sensitivity and specificity levels than other techniques.


describe the characteristics of patients under 15 years of age who underwent PCR for SARS-CoV-2 in a private health provider in the interior of the country between July 1, 2020 and April 30, 2021. Analyze possible factors linked to test positivity. Describe the characteristics of cases with positive PCR


prospective observational study with a retrospective case-control analysis based on the follow-up of a cohort of children under 15 years of age who underwent a PCR test for SARS-CoV-2 in the period analyzed, at a private health provider in the interior of Uruguay. Data were collected during patients’ follow-up according to the institutional protocol that includes: personal data, reason for requesting the PCR, contact data, PCR result and cycle threshold (CT), clinical manifestations and evolution.


2,361 PCRs were performed to children of under 15 years of age (15% of all PCRs in the institution). Average age 8.6 years (range 7 days - 14 years and 11 months); 49% girls and 51% boys. Reason for requesting the test: 78.4% due to previous contact, 14.3% due to symptoms without knowledge of contact and 7.3% prior to hospital admission (emergency or scheduled). Positivity percentage for the entire period 14.7% with significant monthly variability (5.6% in December and 27% in April). The PCR was positive in 346 cases, with a mean CT of 27, and a range between 16.8 and 37.3. No statistical differences were found regarding age and sex between positive and negative cases. Only 1 case was positive PCR prior to hospital admission (OR 0.03 95% CI 0.004 - 0.22) and 20 out of the 611 PCR were requested due to prior institutional contact (school, sports centers, etc.), the difference being statistically significant when the patient was older than 15 years (p 0.029). From the retrospective study of cases (PCR positive) and controls (PCR negative), a statistically significant link (p<0.000001) arose regarding: when the request resulted from a prior contact compared to other causes (OR 5.2 CI 95% 3.28-8.26), when the index case was older than 15 years of age (OR 4.57 95% CI 2.95-7.10) and when the patient and the contact had cohabited (OR 5.28 95% CI 3.97-7.04). There were no hospitalizations or deaths from COVID in the population analyzed.


testing children and adolescents for COVID 19 continues to be a valid strategy in case of suggestive symptoms or contact with a confirmed positive case. In this study, children with a history of contact with a positive case, and older than 15 years, showed a higher proportion of positive PCR results for SARS-CoV-2.

Keywords : COVID-19 Testing; SARS-CoV-2; COVID-19; Child.

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