Pre-admission virus detection during the COVID-19 pandemic in children with and without symptoms of infection.

AIM: Pre-admission viral screening is used only in exceptional situations such as pandemics. We therefore evaluated pre-admission screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus (RSV) and influenza during the COVID-19 pandemic, comparing epidemiology and clinical features of admitted children. METHODS: Children were screened at a paediatric emergency department from 1 March 2020 to 30 June 2022 by nasopharyngeal sampling and polymerase chain reaction kit. We retrospectively retrieved positive results from the laboratory and scrutinised charts of admitted children. RESULTS: Out of 15 927 screened children, 522, 127 and 572 were positive and admitted with RSV, influenza A or SARS-CoV-2, respectively. Of these, 29 (5.6%), 26 (24.1%) and 245 (44.8%) were incidental findings, lacking symptoms of infection. RSV and influenza A were initially absent but re-emerged in the autumn of 2021. The rate of COVID-19 rose when the Omicron variant emerged in December 2021. The median age of children with RSV was 0.3 years, of those with influenza A 6.7 years and of those with COVID-19 1.6 years. Major complications were rare. CONCLUSION: Frequent incidental detections of SARS-CoV-2 likely reflected widespread presence of a mild infection. Clinically, COVID-19 was like other viral respiratory infections in children.

Seizures in hospitalised paediatric patients with SARS-CoV-2 and comparison of severity with seizures in hospitalised paediatric patients with other respiratory viruses during the COVID-19 pandemic: a population-based cohort study.

OBJECTIVE: To study seizures in patients hospitalised due to SARS-CoV-2 infection, and compare their severity with seizures in patients hospitalised due to other viral respiratory tract infections (RTIs). DESIGN: Observational population-based cohort study. SETTING: Northern Stockholm. PATIENTS: Patients aged 1 month-18 years hospitalised due to SARS-CoV-2 with and without seizures, and patients of the same age hospitalised due to other viral RTIs with seizures, between 1 March 2020 and 30 June 2022. MAIN OUTCOME MEASURES: The prevalence of seizures in hospitalised patients due to SARS-CoV-2, the evaluation of assumed predictors of seizures and the comparison of severity markers in patients with SARS-CoV-2 versus other RTIs. RESULTS: 32 of 239 included patients (13.4%) admitted due to SARS-CoV-2 infection had seizures. Central nervous system (CNS) disease and the omicron period had significantly increased OR for seizures (OR: 5.12; CI: 2.06 to 12.72 and OR: 3.01; CI: 1.15 to 7.88, respectively). Seizures in patients with SARS-CoV-2 were more common in children older than 5 years (p=0.001), even in the absence of fever (p=0.007), as compared with other viral RTIs. The duration of hospitalisation was longer in patients with seizures due to other viral RTIs (p=0.023). There was no significant difference regarding severity markers of seizures between the two groups. CONCLUSIONS: CNS disease and the omicron period were risk factors for seizures in patients with SARS-CoV-2, who were older than patients with other RTIs. The severity of seizures was comparable between the two groups; hospitalisation was however longer in patients with other RTIs.

Long term effectiveness of adjuvanted influenza A(H1N1)pdm09 vaccine in children.

BACKGROUND: Immunological studies have indicated that the effectiveness of AS03 adjuvanted monovalent influenza A(H1N1)pdm09 vaccine (Pandemrix) may be of longer duration than what is seen for non-adjuvanted seasonal influenza vaccines. Sixty-nine percent of children 6 months-18 years of age in Stockholm County received at least one dose of Pandemrix during the 2009 pandemic. We studied the effectiveness of the vaccine during the influenza seasons 2010-2011 and 2012-2013 in children hospitalized with virologically confirmed influenza. The season 2011-2012 was not included, since influenza A(H3N2) was the predominant circulating strain. METHODS: In a retrospective case-control study using a modified test-negative design we compared the percentage vaccinated with Pandemrix among children diagnosed with influenza A(H1N1)pdm09 (cases), with that of those diagnosed with influenza A(H3N2) or influenza B (controls) during the two seasons. We excluded children born after July 1, 2009, since only children who were 6 months of age or older received the pandemic vaccine in October-December 2009. RESULTS: During the 2010-2011 season, 3/16 (19%) of children diagnosed with influenza A(H1N1)pdm09, vs. 32/41 (78%) of those with influenza A(H3N2) or influenza B had been vaccinated with Pandemrix in 2009. The odds ratio, after adjustment for sex, age and underlying diseases, for becoming a case when vaccinated with Pandemrix was 0.083 (95%CI 0.014, 0.36), corresponding to a VE of 91.7%. During the season 2012-2013, there was no difference between the two groups; 59% of children diagnosed with influenza A(H3N2)/B and 60% of those with influenza A(H1N1)pdm09 had been vaccinated with Pandemrix in 2009. CONCLUSION: The AS03 adjuvanted monovalent influenza A(H1N1) pdm09 vaccine (Pandemrix) was effective in preventing hospital admission for influenza A(H1N1)pdm09 in children during at least two seasons.

Sinusitis and pneumonia hospitalization after introduction of pneumococcal conjugate vaccine.

BACKGROUND AND OBJECTIVE: Streptococcus pneumoniae is a major cause of pneumonia and sinusitis. Pneumonia kills >1 million children annually, and sinusitis is a potentially serious pediatric disease that increases the risk of orbital and intracranial complications. Although pneumococcal conjugate vaccine (PCV) is effective against invasive pneumococcal disease, its effectiveness against pneumonia is less consistent, and its effect on sinusitis is not known. We compared hospitalization rates due to sinusitis, pneumonia, and empyema before and after sequential introduction of PCV7 and PCV13. METHOD: All children 0 to <18 years old hospitalized for sinusitis, pneumonia, or empyema in Stockholm County, Sweden, from 2003 to 2012 were included in a population-based study of hospital registry data on hospitalizations due to sinusitis, pneumonia, or empyema. Trend analysis, incidence rates, and rate ratios (RRs) were calculated comparing July 2003 to June 2007 with July 2008 to June 2012, excluding the year of PCV7 introduction. RESULTS: Hospitalizations for sinusitis decreased significantly in children aged 0 to <2 years, from 70 to 24 cases per 100 000 population (RR = 0.34, P < .001). Hospitalizations for pneumonia decreased significantly in children aged 0 to <2 years, from 450 to 366 per 100 000 population (RR = 0.81, P < .001) and in those aged 2 to <5 years from 250 to 212 per 100 000 population (RR = 0.85, P = .002). Hospitalization for empyema increased nonsignificantly. Trend analyses showed increasing hospitalization for pneumonia in children 0 to <2 years before intervention and confirmed a decrease in hospitalizations for sinusitis and pneumonia in children aged 0 to <5 years after intervention. CONCLUSIONS: PCV7 and PCV13 vaccination led to a 66% lower risk of hospitalization for sinusitis and 19% lower risk of hospitalization for pneumonia in children aged 0 to <2 years, in a comparison of 4 years before and 4 years after vaccine introduction.

Clinical utility of PCR for common viruses in acute respiratory illness.

BACKGROUND: Acute respiratory illness (ARI) accounts for a large proportion of all visits to pediatric health facilities. Quantitative real-time polymerase chain reaction (qPCR) analyses allow sensitive detection of viral nucleic acids, but it is not clear to what extent specific viruses contribute to disease because many viruses have been detected in asymptomatic children. Better understanding of how to interpret viral findings is important to reduce unnecessary use of antibiotics. OBJECTIVE: To compare viral qPCR findings from children with ARI versus asymptomatic control subjects. METHODS: Nasopharyngeal aspirates were collected from children aged ≤5 years with ARI and from individually matched, asymptomatic, population-based control subjects during a noninfluenza season. Samples were analyzed by using qPCR for 16 viruses. RESULTS: Respiratory viruses were detected in 72.3% of the case patients (n = 151) and 35.4% of the control subjects (n = 74) (P = .001). Rhinovirus was the most common finding in both case patients and control subjects (47.9% and 21.5%, respectively), with a population-attributable proportion of 0.39 (95% confidence interval: 0.01 to 0.62). Metapneumovirus, parainfluenza viruses, and respiratory syncytial virus were highly overrepresented in case patients. Bocavirus was associated with ARI even after adjustment for coinfections with other viruses and was associated with severe disease. Enterovirus and coronavirus were equally common in case patients and control subjects. CONCLUSIONS: qPCR detection of respiratory syncytial virus, metapneumovirus, or parainfluenza viruses in children with ARI is likely to be causative of disease; detection of several other respiratory viruses must be interpreted with caution due to high detection rates in asymptomatic children.

Effectiveness of the monovalent AS03-adjuvanted influenza A(H1N1)pdm09 vaccine against hospitalization in children because of influenza.

We studied the effectiveness of the AS03-adjuvanted monovalent vaccine (Pandemrix(®)) for the prevention of severe pandemic influenza A(H1N1)pdm09 in children, in 2009. All children hospitalized for influenza-like illness in Stockholm County during the peak of the pandemic were included. We compared the frequency of vaccinated children between influenza A(H1N1)pdm09 PCR positive cases and PCR negative controls in a retrospective case-control study. 95 cases and 177 controls were identified. About half of the children in both groups were between 6 months and 2 years of age. Only 1/95 (1%) cases had been vaccinated more than 14 days prior to admission, compared to 23/177 controls (13%), corresponding to a vaccine effectiveness, adjusted for co-morbid conditions, of 91% (95% confidence interval [CI] 30-99). In contrast, the risk for being a case was significantly higher among children vaccinated between 1 and 14 days prior to hospitalization, than among those who were non-vaccinated 13/95 vs. 7/177 (OR 3.6, 95% CI 1.4-9.5). We conclude that a single dose of adjuvanted vaccine was highly protective against hospitalization for influenza A(H1N1)pdm09 in children 6 month to 17 years. The reason for the increased rate of hospitalizations with confirmed influenza in children just following immunization is unclear and should be studied further.