To the Editors:
In December 2019 appeared in China a novel coronavirus, designated as SARS-CoV-2, responsible for a pandemic respiratory disease, known as coronavirus disease, with the Italian outbreak from February 2020. Children appear to have milder symptoms and less severe disease.1 2 , 3 4
Children hospitalized in our pediatric department underwent NS (Copan-503CS01 nasopharyngeal flocked swab) and NPA (Medicoplast mucus extractor 440-ch08), performed from both nostrils, on admission and after 24 hours. SARS-CoV-2 RNA was extracted from the paired samples through nucleic acid amplification, using the RT-PCR.
From March 13 to May 22, 300 paired specimens (NS/NPA) collected from 136 patients (134 hospitalized and 2 outpatients) were tested for SARS-CoV-2.
For clinical aims, we considered positive, to SARS-CoV-2 every patient whose NPA or NS or NPA/NS resulted positive or weak positive.
Out of the 134 patients hospitalized, 18 children tested positive [prevalence 13.4%, 95% confidence interval (CI) 8.2%–20.4%]; among the latter, 13 of them and 2 outpatient children were followed collecting their paired specimens until both resulted negative 24 hours apart.
Of the 300 paired specimens evaluated: 276 were concordant, 24 were discordant, so the naĂ¯ve concordance was 92.0% (95% CI 88.3%–94.6%) with Cohen’s kappa (K) 0.63. Among the paired specimens whose NPA resulted positive, 41.9% (95% CI 28.2%–56.9%) had NS negative; while among the paired specimens whose NPA resulted negative, 2.3% (95% CI 1.1%–5.1%) had NS positive.
Considering NPA as the gold standard for detection of SARS-CoV-2, we calculated sensitivities and specificities of NS. The overall sensitivity of NS was 58.1% (95% CI 43.1%–71.8%) and the specificity was 97.7% (95% CI 94.9%–98.9%). Since the different practice in specimen collection, we divided our cohort according to the children’s age (<6 or ≥6 years, Table 1 ). Among children under 6 years, the concordance was K = 0.67. Regarding children of 6 years or older, the concordance was K = 0.60.
TABLE 1.: NS and NPA Results
The NS has, in any case, a low sensitivity in detecting SARS-CoV-2 in children when referred to NPA. Our results, the first we know are available, suggest to prefer the collection of NPA whenever possible for the detection of SARS-CoV-2 in children.
ACKNOWLEDGMENTS
Testing Pediatric COVID-19 (TPC-19) study group: Paola Marchisio, MD, Silvana Castaldi, MD, Elia Biganzoli, PhD, Patrizia Boracchi, Samantha Bosis, MD, Giovanna Lunghi, MD, Ferruccio Ceriotti, MD, Giuseppe Bertolozzi, MD, Carlo Agostoni, MD, and Andrea Gori, MD
Ester Capecchi, MD Giada Maria Di Pietro, MD Ester Luconi, MSc
REFERENCES
1. Ludvigsson JF. Systematic review of COVID-19 in children shows milder cases and a better prognosis than adults. Acta Paediatr. 2020;109:1088–1095.
2. Mawaddah A, Gendeh HS, Lum SG, et al. Upper respiratory tract sampling in COVID-19. Malays J Pathol. 2020;42:23–35.
3. Loeffelholz MJ, Tang YW. Laboratory diagnosis of emerging human coronavirus infections—the state of the art. Emerg Microbes Infect. 2020;9:747–756.
4. Lambert SB, Whiley DM, O’Neill NT, et al. Comparing nose-throat swabs and nasopharyngeal aspirates collected from children with symptoms for respiratory virus identification using real-time polymerase chain reaction. Pediatrics. 2008;122:e615–e620.
