Background. The burden of human coronavirus (HCoV)-associated respiratory tract infections (RTIs) in hospitalized children is poorly defined. We studied the occurrence and hospitalization rates of HCoV over 9 years.Methods. Children from Sør-Trøndelag County, Norway, hospitalized with RTIs and asymptomatic controls, were prospectively enrolled from 2006 to 2015. Nasopharyngeal aspirates were analyzed with semiquantitative polymerase chain reaction (PCR) tests for HCoV subtypes OC43, 229E, NL63, and HKU1, and 13 other respiratory pathogens.Results. HCoV was present in 9.1% (313/3458) of all RTI episodes: 46.6% OC43, 32.3% NL63, 16.0% HKU1, and 5.8% 229E. Hospitalization rates for HCoV-positive children with lower RTIs were 1.5 and 2.8 per 1000 <5 and <1 years of age, respectively. The detection rate among controls was 10.2% (38/373). Codetections occurred in 68.1% of the patients and 68.4% of the controls. In a logistic regression analysis, high HCoV genomic loads (cycle threshold <28 in PCR analysis) were associated with RTIs (odds ratio = 3.12, P = .016) adjusted for relevant factors.Conclusions. HCoVs occurred in 1 of 10 hospitalized children with RTIs and asymptomatic controls. A high HCoV genomic load was associated with RTI. HCoVs are associated with a substantial burden of RTIs in need of hospitalization.Keywords. human coronaviruses; children; hospitalization rates; respiratory tract infections; asymptomatic controls. METHODS Study SettingThe study was conducted at the Children's Department at St Olavs Hospital in Trondheim, Norway. The Department of Pediatrics is the sole pediatric reference center for approximately 59 000 children in Sør-Trøndelag County. Study PopulationFrom November 2006 to July 2015 we conducted a prospective surveillance study, enrolling all children admitted to the Children's Department at St Olavs Hospital with symptoms and

Background: The clinical impact of common human coronavirus (cHCoV) remains unclear. We studied the clinical manifestations of pediatric cHCoV infections and the possible modifying effects of codetected human rhinovirus (RV) and respiratory syncytial virus (RSV). Methods: We used data from an 11-year-long prospective study of hospitalized children with community-acquired respiratory tract infections. Nasopharyngeal aspirates were analyzed with real-time polymerase chain reaction assay for cHCoV OC43, NL63, HKU1 and 229E, and 15 other respiratory viruses. We assessed disease severity based on the clinical factors hospitalization length, oxygen requirement, other respiratory support and supplementary fluids. Results: cHCoV was detected in 341 (8%) of 4312 children. Among 104 children with single cHCoV detections, 58 (56%) had lower respiratory tract infection (LRTI) and 20 (19%) developed severe disease. The proportion with severe disease was lower among single cHCoV detections compared with single RSV detections (338 of 870; 39%), but similar to single RV detections (136 of 987; 14%). Compared with single cHCoV, codetected cHCoV-RSV was more often associated with LRTI (86 of 89; 97%) and severe disease (adjusted odds ratio, 3.3; 95% confidence interval: 1.6–6.7). LRTI was more frequent in codetected cHCoV-RV (52 of 68; 76%) than single cHCoV, but the risk of severe disease was lower (adjusted odds ratios, 0.3; 95% confidence interval: 0.1–1.0). Conclusions: cHCoV was associated with severe LRTI in hospitalized children. Viral codetections were present in two-thirds. Codetections of cHCoV-RV were associated with lower proportions of severe disease, suggesting a modifying effect of RV on HCoV.

Background The role of Parechovirus A (PeV-A) in hospitalized children with respiratory tract infections (RTIs) is unclear. We studied the occurrence and impact of PeV-A over 10 years. Methods Children from Sør-Trøndelag County, Norway, hospitalized with RTI and a comparison group of asymptomatic children admitted to elective surgery, were prospectively enrolled from 2006 to 2016. Nasopharyngeal aspirates were cultured and analyzed with polymerase chain reaction tests for PeV-A and 19 other pathogens. The cycle threshold levels of PeV-A were reported as measures of viral genomic loads. Parechovirus A-positive samples were genotyped by amplification and sequencing of the VP3/VP1 junction. Results Parechovirus A was detected in 8.8% (323/3689) patients with RTI and in 10.1% (45/444) of the children in the comparison group (P = .34). Parechovirus A genotyping (n = 188) revealed PeV-A1 (n = 121), PeV-A3 (n = 15), PeV-A5 (n = 6), and PeV-A6 (n = 46). Viral codetections occurred in 95% of patients and in 84% of the children in the comparison group (P = .016). In multivariable logistic regression analysis, RTI was unrelated to PeV-A genomic loads, adjusted for other viruses and covariates. Similar results were found for PeV-A1 and PeV-A6. Conclusions Parechovirus A and viral codetections were common in hospitalized children with RTI and asymptomatic children in a comparison group. Our findings suggest that PeV-A has a limited role in hospitalized children with RTI.

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Background Human bocavirus 1 (HBoV1) is frequently codetected with other viruses, and detected in asymptomatic children. Thus, the burden of HBoV1 respiratory tract infections (RTI) has been unknown. Using HBoV1-mRNA to indicate true HBoV1 RTI, we assessed the burden of HBoV1 in hospitalized children and the impact of viral codetections, compared with RSV. Methods Over 11 years, we enrolled 4,879 children &lt;16 years old admitted with RTI. Nasopharyngeal aspirates were analyzed with polymerase chain reaction for HBoV1-DNA, HBoV1-mRNA and 19 other pathogens. Results HBoV1-mRNA was detected in 2.7% (130/4850) samples, modestly peaking in autumn and winter. Forty-three percent with HBoV1 mRNA were 12-17 months old, and only 5% were &lt;6 months old. A total of 73.8% had viral codetections. It was more likely to detect HBoV1-mRNA if HBoV1-DNA was detected alone (OR: 3.9, 95% CI: 1.7-8.9) or with 1 viral codetection (OR: 1.9, 95% CI: 1.1-3.3), compared to ≥2 codetections. Codetection of severe viruses like RSV had lower odds for HBoV1-mRNA (OR: 0.34, 95% CI: 0.19-0.61). The yearly lower RTI (LRTI) hospitalization rate per 1,000 children &lt;5 years was 0.7 for HBoV1-mRNA and 8.7 for RSV. Conclusions True HBoV1 RTI is most likely when HBoV1-DNA is detected alone, or with one codetected virus. Hospitalization due to HBoV1 LRTI is 10-12 times less common than RSV.