PCR gene targets and sources from which the primers were obtained.

<p>This multiplex nested PCR was performed in all samples independently of any diagnostic test carried out by the referring hospital.</p><p>PCR gene targets and sources from which the primers were obtained.</p

Pathogen prevalence in the main and replication cohorts shown as number detected in nasopharyngeal samples considering the age of the children.

<p>Only the more prevalent viruses are presented.</p

Associations among respiratory pathogens in hospitalized children in the GENDRES and UK cohorts.

<p>Associations among respiratory pathogens in hospitalized children in the GENDRES and UK cohorts.</p

Summary of the characteristics of RSV cohort and comparison between those with positive and negative blood PCR for bacteria.

<p>General data are presented as percentages or means with 95% confidence intervals. Different statistical models were used to assess the association between the variables: Fisher’s exact test (1) for discrete variables and Wilcoxon test (2) for continuous variables.</p

Severity parameters for the patients: Wood Downes score, GENVIP score, length of hospitalization, oxygen, respiratory support, respiratory distress and PICU admission.

<p>Patients are classified as: positive RSV in nasopharyngeal sample, positive RSV with confirmed bacteremia, and positive RSV and suspected bacterial superinfection.</p

Description of RSV infected patients with positive blood bacterial PCR.

<p>Abbreviations: NINV: noninvasive ventilation; INV: invasive ventilation; RSV: respiratory syncytial virus; PCR: polymerase chain reaction.</p

Target genes and organisms detected by nested PCR.

<p>Target genes and organisms detected by nested PCR.</p

Comparison of virus and disease severity of the main cohort considering the virus as single pathogen or as co-infection in the sample.

<p>Different statistical models were considered to study the bivariate association between the variables depending on the dependent variable. A binary logistic model was used for the binary variables oxygen needed and respiratory support needed, and a negative binomial regression model for counted data (hospital stay length). Data are presented as OR (confidence interval 95%) and the level of statistical significance was set at 0.05.</p

Relationship between demographic and clinical variables with mono-infection and co-infection is shown for both GENDRES and UK cohort.

<p>The correlation was analysed using simple logistic regression. Data are presented as OR (95% confidence interval) and <i>P</i>-value. The characteristics of the two cohorts analyzed were compared and when P-value results were significant when different: the GENDRES cohort and the UK cohort. <i>P</i>-value results from the comparison between both cohorts. A <i>P</i>-value < 0.005 was considered significant.</p

Description of the characteristics of the two cohorts analyzed: the GENDRES cohort and the UK cohort.

<p><i>P</i>-value results from the comparison between both cohorts. A <i>P</i>-value < 0.05 was considered significant.</p