Accuracy of Influenza ICD-10 Diagnosis Codes in Identifying Influenza Illness in Children

Importance

Studies of influenza in children commonly rely on coded diagnoses, yet the ability of International Classification of Diseases, Ninth Revision codes to identify influenza in the emergency department (ED) and hospital is highly variable. The accuracy of newer International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes to identify influenza in children is unknown.

Objective

To determine the accuracy of ICD-10 influenza discharge diagnosis codes in the pediatric ED and inpatient settings.

Design, Setting, and Participants

Children younger than 18 years presenting to the ED or inpatient settings with fever and/or respiratory symptoms at 7 US pediatric medical centers affiliated with the Centers for Disease Control and Prevention-sponsored New Vaccine Surveillance Network from December 1, 2016, to March 31, 2020, were included in this cohort study. Nasal and/or throat swabs were collected for research molecular testing for influenza, regardless of clinical testing. Data, including ICD-10 discharge diagnoses and clinical testing for influenza, were obtained through medical record review. Data analysis was performed in August 2023.

Main Outcomes and Measures

The accuracy of ICD-10-coded discharge diagnoses was characterized using molecular clinical or research laboratory test results as reference. Measures included sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Estimates were stratified by setting (ED vs inpatient) and age (0-1, 2-4, and 5-17 years).

Results

A total of 16 867 children in the ED (median [IQR] age, 2.0 [0.0-4.0] years; 9304 boys [55.2%]) and 17 060 inpatients (median [IQR] age, 1.0 [0.0-4.0] years; 9798 boys [57.4%]) were included. In the ED, ICD-10 influenza diagnoses were highly specific (98.0%; 95% CI, 97.8%-98.3%), with high PPV (88.6%; 95% CI, 88.0%-89.2%) and high NPV (85.9%; 95% CI, 85.3%-86.6%), but sensitivity was lower (48.6%; 95% CI, 47.6%-49.5%). Among inpatients, specificity was 98.2% (95% CI, 98.0%-98.5%), PPV was 82.8% (95% CI, 82.1%-83.5%), sensitivity was 70.7% (95% CI, 69.8%-71.5%), and NPV was 96.5% (95% CI, 96.2%-96.9%). Accuracy of ICD-10 diagnoses varied by patient age, influenza season definition, time between disease onset and testing, and clinical setting.

Conclusions and Relevance

In this large cohort study, influenza ICD-10 discharge diagnoses were highly specific but moderately sensitive in identifying laboratory-confirmed influenza; the accuracy of influenza diagnoses varied by clinical and epidemiological factors. In the ED and inpatient settings, an ICD-10 diagnosis likely represents a true-positive influenza case.

Medical Costs of RSV-associated Hospitalizations and Emergency Department Visits in Children Aged <5 years: Observational Findings from the New Vaccine Surveillance Network (NVSN), 2016-2019

OBJECTIVE

To assess medical costs of hospitalizations and emergency department (ED) care associated with respiratory syncytial virus (RSV) disease in children enrolled in the New Vaccine Surveillance Network.

STUDY DESIGN

We used accounting and prospective surveillance data from six pediatric health systems to assess direct medical costs from laboratory-confirmed RSV-associated hospitalizations (n=2,007) and ED visits (n=1,267) from 2016 through 2019 among children aged <5 years. We grouped costs into categories relevant to clinical care and administrative billing practices. We examined RSV-associated medical costs by care setting using descriptive and bivariate analyses. We assessed associations between known RSV risk factors and hospitalization costs and length of stay (LOS) using chi-square tests of association.

RESULTS

The median cost was $7,100 (IQR: $4,006-$13,355) per hospitalized child and $503 (IQR: $387-$930) per ED visit. Eighty percent (n=2,628) of our final sample were children aged <2 years. Fewer weeks' gestational age (GA) was associated with higher median costs in hospitalized children [p<0.001, ≥37 weeks' GA: $6,840 ($3,905-$12,450); 29-36 weeks' GA: $7,721 ($4,362-$15,274); <29 w weeks' GA: $9,131 ($4,518-$19,924)]. Full-term infants accounted for 70% of the total expenditures in our sample. Almost three quarters of the healthcare dollars spent originated in children under 12 months of age; the primary age group targeted by recommended RSV prophylactics.

CONCLUSIONS

Reducing the cost burden for RSV-associated medical care in young children will require prevention of RSV in all young children, not just high-risk infants. Newly available maternal vaccine and immunoprophylaxis products could substantially reduce RSV-associated medical costs.

Early Estimate of Nirsevimab Effectiveness for Prevention of Respiratory Syncytial Virus-Associated Hospitalization Among Infants Entering Their First Respiratory Syncytial Virus Season - New Vaccine Surveillance Network, October 2023-February 2024

Respiratory syncytial virus (RSV) is the leading cause of hospitalization among infants in the United States. In August 2023, CDC's Advisory Committee on Immunization Practices recommended nirsevimab, a long-acting monoclonal antibody, for infants aged <8 months to protect against RSV-associated lower respiratory tract infection during their first RSV season and for children aged 8-19 months at increased risk for severe RSV disease. In phase 3 clinical trials, nirsevimab efficacy against RSV-associated lower respiratory tract infection with hospitalization was 81% (95% CI = 62%-90%) through 150 days after receipt; post-introduction effectiveness has not been assessed in the United States. In this analysis, the New Vaccine Surveillance Network evaluated nirsevimab effectiveness against RSV-associated hospitalization among infants in their first RSV season during October 1, 2023-February 29, 2024. Among 699 infants hospitalized with acute respiratory illness, 59 (8%) received nirsevimab ≥7 days before symptom onset. Nirsevimab effectiveness was 90% (95% CI = 75%-96%) against RSV-associated hospitalization with a median time from receipt to symptom onset of 45 days (IQR = 19-76 days). The number of infants who received nirsevimab was too low to stratify by duration from receipt; however, nirsevimab effectiveness is expected to decrease with increasing time after receipt because of antibody decay. Although nirsevimab uptake and the interval from receipt of nirsevimab were limited in this analysis, this early estimate supports the current nirsevimab recommendation for the prevention of severe RSV disease in infants. Infants should be protected by maternal RSV vaccination or infant receipt of nirsevimab.

Respiratory Syncytial Virus-Associated Hospitalizations Among Children <5 Years Old: 2016 to 2020

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of hospitalization in US infants. Accurate estimates of severe RSV disease inform policy decisions for RSV prevention.

METHODS

We conducted prospective surveillance for children <5 years old with acute respiratory illness from 2016 to 2020 at 7 pediatric hospitals. We interviewed parents, reviewed medical records, and tested midturbinate nasal ± throat swabs by reverse transcription polymerase chain reaction for RSV and other respiratory viruses. We describe characteristics of children hospitalized with RSV, risk factors for ICU admission, and estimate RSV-associated hospitalization rates.

RESULTS

Among 13 524 acute respiratory illness inpatients <5 years old, 4243 (31.4%) were RSV-positive; 2751 (64.8%) of RSV-positive children had no underlying condition or history of prematurity. The average annual RSV-associated hospitalization rate was 4.0 (95% confidence interval [CI]: 3.8-4.1) per 1000 children <5 years, was highest among children 0 to 2 months old (23.8 [95% CI: 22.5-25.2] per 1000) and decreased with increasing age. Higher RSV-associated hospitalization rates were found in premature versus term children (rate ratio = 1.95 [95% CI: 1.76-2.11]). Risk factors for ICU admission among RSV-positive inpatients included: age 0 to 2 and 3 to 5 months (adjusted odds ratio [aOR] = 1.97 [95% CI: 1.54-2.52] and aOR = 1.56 [95% CI: 1.18-2.06], respectively, compared with 24-59 months), prematurity (aOR = 1.32 [95% CI: 1.08-1.60]) and comorbid conditions (aOR = 1.35 [95% CI: 1.10-1.66]).

CONCLUSIONS

Younger infants and premature children experienced the highest rates of RSV-associated hospitalization and had increased risk of ICU admission. RSV prevention products are needed to reduce RSV-associated morbidity in young infants.

Interim Estimates of 2023-24 Seasonal Influenza Vaccine Effectiveness - United States

In the United States, annual influenza vaccination is recommended for all persons aged ≥6 months. Using data from four vaccine effectiveness (VE) networks during the 2023-24 influenza season, interim influenza VE was estimated among patients aged ≥6 months with acute respiratory illness-associated medical encounters using a test-negative case-control study design. Among children and adolescents aged 6 months-17 years, VE against influenza-associated outpatient visits ranged from 59% to 67% and against influenza-associated hospitalization ranged from 52% to 61%. Among adults aged ≥18 years, VE against influenza-associated outpatient visits ranged from 33% to 49% and against hospitalization from 41% to 44%. VE against influenza A ranged from 46% to 59% for children and adolescents and from 27% to 46% for adults across settings. VE against influenza B ranged from 64% to 89% for pediatric patients in outpatient settings and from 60% to 78% for all adults across settings. These findings demonstrate that the 2023-24 seasonal influenza vaccine is effective at reducing the risk for medically attended influenza virus infection. CDC recommends that all persons aged ≥6 months who have not yet been vaccinated this season get vaccinated while influenza circulates locally.

Seasonality, clinical characteristics, and outcomes of respiratory syncytial virus disease by subtype among children less than five years old, New Vaccine Surveillance Network, United States, 2016-2020

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of acute respiratory illnesses (ARI) in children. RSV can be broadly categorized into two major subtypes (A and B). RSV subtypes have been known to co-circulate with variability in different regions of the world. Clinical associations with viral subtype have been studied among children with conflicting findings such that no conclusive relationships between RSV subtype and severity have been established.

METHODS

During 2016-2020, children <5 years old were enrolled in prospective surveillance in the emergency department (ED) or inpatient (IP) settings from seven U.S. pediatric medical centers. Surveillance data collection included parent/guardian interviews, chart reviews, and collection of mid-turbinate nasal +/- throat swabs for RSV (RSV-A, RSV-B, and Untyped) by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Among 6398 RSV-positive children <5 years old, 3424 (54%) had subtype RSV-A infections, 2602 (41%) had subtype RSV-B infections, and 272 (5%) were not typed, inconclusive, or mixed infections. In both adjusted and unadjusted analyses, RSV-A-positive children were more likely to be hospitalized, as well as when restricted to <1 year. By season, RSV-A and RSV-B co-circulated in varying levels, with one subtype dominating proportionally.

CONCLUSION

Findings indicate that RSV-A and RSV-B may only be marginally clinically distinguishable but both subtypes are associated with medically attended illness in children <5 years old. Furthermore, circulation of RSV subtypes varies substantially each year, seasonally and geographically. With introduction of new RSV prevention products, this highlights the importance of continued monitoring of RSV-A and RSV-B subtypes.

Maternal Vaccine Effectiveness Against Influenza-Associated Hospitalizations and Emergency Department Visits in Infants

Importance

Influenza virus infection during pregnancy is associated with severe maternal disease and may be associated with adverse birth outcomes. Inactivated influenza vaccine during pregnancy is safe and effective and can protect young infants, but recent evidence, particularly after the 2009 novel influenza A (H1N1) pandemic, is limited.

Objective

To evaluate the effectiveness of influenza vaccination during pregnancy against laboratory-confirmed influenza-associated hospitalizations and emergency department (ED) visits in infants younger than 6 months.

Design, Setting, and Participants

This was a prospective, test-negative case-control study using data from the New Vaccine Surveillance Network from the 2016 to 2017 through 2019 to 2020 influenza seasons. Infants younger than 6 months with an ED visit or hospitalization for acute respiratory illness were included from 7 pediatric medical institutions in US cities. Control infants with an influenza-negative molecular test were included for comparison. Data were analyzed from June 2022 to September 2023.

Exposure

Maternal influenza vaccination during pregnancy.

Main Outcomes and Measures

We estimated maternal vaccine effectiveness against hospitalizations or ED visits in infants younger than 6 months, those younger than 3 months, and by trimester of vaccination. Maternal vaccination status was determined using immunization information systems, medical records, or self-report. Vaccine effectiveness was estimated by comparing the odds of maternal influenza vaccination 14 days or more before delivery in infants with influenza vs those without.

Results

Of 3764 infants (223 with influenza and 3541 control infants), 2007 (53%) were born to mothers who were vaccinated during pregnancy. Overall vaccine effectiveness in infants was 34% (95% CI, 12 to 50), 39% (95% CI, 12 to 58) against influenza-associated hospitalizations, and 19% (95% CI, -24 to 48) against ED visits. Among infants younger than 3 months, effectiveness was 53% (95% CI, 30 to 68). Effectiveness was 52% (95% CI, 30 to 68) among infants with mothers who were vaccinated during the third trimester and 17% (95% CI, -15 to 40) among those with mothers who were vaccinated during the first or second trimesters.

Conclusions and Relevance

Maternal vaccination was associated with reduced odds of influenza-associated hospitalizations and ED visits in infants younger than 6 months. Effectiveness was greatest among infants younger than 3 months, for those born to mothers vaccinated during the third trimester, and against influenza-associated hospitalizations.

SARS-CoV-2 Epidemiology and COVID-19 mRNA Vaccine Effectiveness Among Infants and Children Aged 6 Months-4 Years - New Vaccine Surveillance Network, United States, July 2022-September 2023

SARS-CoV-2 infection in young children is often mild or asymptomatic; however, some children are at risk for severe disease. Data describing the protective effectiveness of COVID-19 mRNA vaccines against COVID-19-associated emergency department (ED) visits and hospitalization in this population are limited. Data from the New Vaccine Surveillance Network, a prospective population-based surveillance system, were used to estimate vaccine effectiveness using a test-negative, case-control design and describe the epidemiology of SARS-CoV-2 in infants and children aged 6 months-4 years during July 1, 2022-September 30, 2023. Among 7,434 children included, 5% received a positive SARS-CoV-2 test result, and 95% received a negative test result; 86% were unvaccinated, 4% had received 1 dose of any vaccine product, and 10% had received ≥2 doses. When compared with receipt of no vaccines among children, receipt of ≥2 COVID-19 mRNA vaccine doses was 40% effective (95% CI = 8%-60%) in preventing ED visits and hospitalization. These findings support existing recommendations for COVID-19 vaccination of young children to reduce COVID-19-associated ED visits and hospitalization.

Sustained Within-season Vaccine Effectiveness Against Influenza-associated Hospitalization in Children: Evidence From the New Vaccine Surveillance Network, 2015-2016 Through 2019-2020

BACKGROUND

Adult studies have demonstrated within-season declines in influenza vaccine effectiveness (VE); data in children are limited.

METHODS

We conducted a prospective, test-negative study of children 6 months through 17 years hospitalized with acute respiratory illness at 7 pediatric medical centers during the 2015-2016 through 2019-2020 influenza seasons. Case-patients were children with an influenza-positive molecular test matched by illness onset to influenza-negative control-patients. We estimated VE [100% × (1 - odds ratio)] by comparing the odds of receipt of ≥1 dose of influenza vaccine ≥14 days before illness onset among influenza-positive children to influenza-negative children. Changes in VE over time between vaccination date and illness onset date were estimated using multivariable logistic regression.

RESULTS

Of 8430 children, 4653 (55%) received ≥1 dose of influenza vaccine. On average, 48% were vaccinated through October and 85% through December each season. Influenza vaccine receipt was lower in case-patients than control-patients (39% vs 57%, P < .001); overall VE against hospitalization was 53% (95% confidence interval [CI]: 46, 60%). Pooling data across 5 seasons, the odds of influenza-associated hospitalization increased 4.2% (-3.2%, 12.2%) per month since vaccination, with an average VE decrease of 1.9% per month (n = 4000, P = .275). Odds of hospitalization increased 2.9% (95% CI: -5.4%, 11.8%) and 9.6% (95% CI: -7.0%, 29.1%) per month in children ≤8 years (n = 3084) and 9-17 years (n = 916), respectively. These findings were not statistically significant.

CONCLUSIONS

We observed minimal, not statistically significant within-season declines in VE. Vaccination following current Advisory Committee on Immunization Practices (ACIP) guidelines for timing of vaccine receipt remains the best strategy for preventing influenza-associated hospitalizations in children.

Circulation of Rhinoviruses and/or Enteroviruses in Pediatric Patients With Acute Respiratory Illness Before and During the COVID-19 Pandemic in the US

IMPORTANCE

Rhinoviruses and/or enteroviruses, which continued to circulate during the COVID-19 pandemic, are commonly detected in pediatric patients with acute respiratory illness (ARI). Yet detailed characterization of rhinovirus and/or enterovirus detection over time is limited, especially by age group and health care setting.

OBJECTIVE

To quantify and characterize rhinovirus and/or enterovirus detection before and during the COVID-19 pandemic among children and adolescents seeking medical care for ARI at emergency departments (EDs) or hospitals.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from the New Vaccine Surveillance Network (NVSN), a multicenter, active, prospective surveillance platform, for pediatric patients who sought medical care for fever and/or respiratory symptoms at 7 EDs or hospitals within NVSN across the US between December 2016 and February 2021. Persons younger than 18 years were enrolled in NVSN, and respiratory specimens were collected and tested for multiple viruses.

MAIN OUTCOMES AND MEASURES

Proportion of patients in whom rhinovirus and/or enterovirus, or another virus, was detected by calendar month and by prepandemic (December 1, 2016, to March 11, 2020) or pandemic (March 12, 2020, to February 28, 2021) periods. Month-specific adjusted odds ratios (aORs) for rhinovirus and/or enterovirus-positive test results (among all tested) by setting (ED or inpatient) and age group (<2, 2-4, or 5-17 years) were calculated, comparing each month during the pandemic to equivalent months of previous years.

RESULTS

Of the 38 198 children and adolescents who were enrolled and tested, 11 303 (29.6%; mean [SD] age, 2.8 [3.7] years; 6733 boys [59.6%]) had rhinovirus and/or enterovirus-positive test results. In prepandemic and pandemic periods, rhinoviruses and/or enteroviruses were detected in 29.4% (9795 of 33 317) and 30.9% (1508 of 4881) of all patients who were enrolled and tested and in 42.2% (9795 of 23 236) and 73.0% (1508 of 2066) of those with test positivity for any virus, respectively. Rhinoviruses and/or enteroviruses were the most frequently detected viruses in both periods and all age groups in the ED and inpatient setting. From April to September 2020 (pandemic period), rhinoviruses and/or enteroviruses were detectable at similar or lower odds than in prepandemic years, with aORs ranging from 0.08 (95% CI, 0.04-0.19) to 0.76 (95% CI, 0.55-1.05) in the ED and 0.04 (95% CI, 0.01-0.11) to 0.71 (95% CI, 0.47-1.07) in the inpatient setting. However, unlike some other viruses, rhinoviruses and/or enteroviruses soon returned to prepandemic levels and from October 2020 to February 2021 were detected at similar or higher odds than in prepandemic months in both settings, with aORs ranging from 1.47 (95% CI, 1.12-1.93) to 3.01 (95% CI, 2.30-3.94) in the ED and 1.36 (95% CI, 1.03-1.79) to 2.44 (95% CI, 1.78-3.34) in the inpatient setting, and in all age groups. Compared with prepandemic years, during the pandemic, rhinoviruses and/or enteroviruses were detected in patients who were slightly older, although most (74.5% [1124 of 1508]) were younger than 5 years.

CONCLUSIONS AND RELEVANCE

Results of this study show that rhinoviruses and/or enteroviruses persisted and were the most common respiratory virus group detected across all pediatric age groups and in both ED and inpatient settings. Rhinoviruses and/or enteroviruses remain a leading factor in ARI health care burden, and active ARI surveillance in children and adolescents remains critical for defining the health care burden of respiratory viruses.

2196. Frequencies of Adenovirus Types in U.S. Children with Acute Respiratory Illness, 2016–2019

Background

Adenovirus (AdV) is a common cause of acute respiratory illness (ARI). Multiple respiratory AdV types have been identified in humans, but it remains unclear which are the most common in U.S. children with ARI.

Methods

We conducted a multicenter, prospective viral surveillance study at seven U.S. children’s hospitals, the New Vaccine Surveillance Network, during 12/1/16–11/30/19, prior to the COVID-19 pandemic. Children < 18 years of age seen in the emergency department or hospitalized with fever and/or respiratory symptoms were enrolled, and mid-turbinate nasal +/- throat swabs were tested using multiplex respiratory pathogen assays or real time polymerase chain reaction (PCR) test for AdV, respiratory syncytial virus (RSV), human metapneumovirus, rhinovirus/enterovirus (RV), influenza, parainfluenza viruses, and endemic coronaviruses. AdV-positive specimens were subsequently typed using single-plex qPCR assays targeting sequences in the hexon gene specific for types 1-7, 11, 14, 16 and 21. Demographics, clinical characteristics, and outcomes were compared between AdV types.

Results

Of 29,381 enrolled children, 2,106 (7.2%) tested positive for AdV. The distribution of types among the 1,330 (63.2%) successfully typed specimens were as follows: 31.7% AdV-2, 28.9% AdV-1, 15.3% AdV-3, 7.9% AdV-5, 5.9% AdV-7, 1.4% AdV-4, 1.2% AdV-6, 0.5% AdV-14, 0.2% AdV-21, 0.1% AdV-11, and 7.0% ≥1 AdV type. Most children with AdV-1 or AdV-2 detection were < 5 years of age (Figure 1a). Demographic and clinical characteristics varied by AdV types, including age, race/ethnicity, smoke exposure, daycare/school attendance, and hospitalization (Table 1). Co-detection with other viruses was common among all AdV types, with RV and RSV being the most frequently co-detected (Figure 1b). Fever and cough were the most common symptoms for all AdV types (Figure 2). Children with AdV-7 detected as single pathogen had higher odds of hospitalization (adjusted odds ratio 6.34 [95% CI: 3.10, 12.95], p= 0.027).

Conclusion

AdV-2 and AdV-1 were the most frequently detected AdV types among children over the 3-year study period. Notable clinical heterogeneity of the AdV types warrants further surveillance studies to identify AdV types that could be targeted for pediatric vaccine development.

Disclosures

Rangaraj Selvarangan, BVSc, PhD, D(ABMM), FIDSA, F(AAM), BioFire: Grant/Research Support|Luminex: Grant/Research Support John Williams, MD, GlaxoSmithKline: Advisor/Consultant|Quidel: Advisor/Consultant Mary A. Staat, MD, MPH, Centers for Disease Control and Prevention: Grant/Research Support|Cepheid: Grant/Research Support|National Institute of Health: Grant/Research Support|Uptodate: Royalties Christopher J Harrison, MD, Astellas: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|Pediatric news: Honoraria|Pfizer: Grant/Research Support Mary E. Moffatt, M.D., Becton and Dickinson and Company: Stocks/Bonds|Biogen: Stocks/Bonds|Coloplast B: Stocks/Bonds|Express Scripts: Stocks/Bonds|Novo Nordisk A/S Spons ADR: Stocks/Bonds|Novo Nordisk A/S-B: Stocks/Bonds|Steris PLC: Stocks/Bonds|Stryker Corp: Stocks/Bonds|Thermo Fisher Scientific: Stocks/Bonds Geoffrey A. Weinberg, MD, Merck & Co.: Honoraria|Merck & Co.: Honoraria for composing and reviewing textbook chapters, Merck Manual of Therapeutics Janet A. Englund, MD, AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccines: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Natasha B. Halasa, MD, Quidel: Grant/Research Support|Quidel: equipment donation|Sanofi: Grant/Research Support|Sanofi: HAI testing and vaccine donation.

2167. Use and Timing of Antiviral Therapy for Influenza in Hospitalized U.S. Children, 2016–2020

Background

According to the 2018 Infectious Diseases Society of America (IDSA) clinical practice guidelines and Centers for Disease Control and Prevention (CDC) guidance, clinicians should start antiviral treatment as soon as possible for children who are hospitalized with suspected or confirmed influenza. We assessed the use of influenza-specific antiviral therapy in children hospitalized with symptoms of acute respiratory illness and laboratory-confirmed influenza.

Methods

We conducted active, population-based surveillance of children hospitalized with fever and/or respiratory symptoms (12/01/2016–02/28/2020) at the seven U.S. medical centers that comprise the CDC New Vaccine Surveillance Network. We excluded children who did not undergo clinical testing (by rapid antigen testing or nucleic acid amplification test [NAAT]) or research testing (by NAAT) for influenza, those who presented out of influenza season (site- and season-specific), and those whose date of antiviral therapy or whether antiviral therapy was given was unknown. We assessed the use of influenza-specific antiviral therapy in this cohort and defined timely antiviral therapy as administration within 2 days of hospitalization.

Results

Of 11,275 eligible children, 1,149 (10.2%) tested positive for influenza by clinical and/or research assays (Table 1). Overall, 154 influenza cases (13.4%) were detected by clinical testing only, 428 (37.2%) by research testing only, and 567 (49.3%) by both. During their influenza-associated hospitalization, 620 children (54.0%) received influenza-specific antivirals, and therapy was timely in 572 cases (92.3%). Of those who tested positive clinically, 445/721 (61.7%) received timely antiviral therapy, 38 (5.3%) received delayed antiviral therapy, and 238 (33.0%) received no antiviral therapy. Oseltamivir was the antiviral used in all treated cases. The distribution of antiviral-treated cases varied by race and Hispanic origin and study site, but not by age at presentation or influenza season (Figure 1). Table 1

Demographic characteristics of 1,149 children with influenza enrolled in the New Vaccine Surveillance Network over four influenza seasons between December 1, 2016, and February 28, 2020. Figure 1Proportions of children with influenza enrolled in the New Vaccine Surveillance Network who received timely, delayed, or no antiviral therapy by age at presentation, race and Hispanic origin, study site, and influenza season (N=1,149).

Conclusion

Although antiviral therapy is recommended for all influenza-associated hospitalizations in children, antiviral prescribing remains suboptimal. Further studies would help identify and address barriers to antiviral therapy in children with influenza.

Disclosures

John Williams, MD, GlaxoSmithKline: Advisor/Consultant|Quidel: Advisor/Consultant Janet A. Englund, MD, AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccines: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Rangaraj Selvarangan, BVSc, PhD, D(ABMM), FIDSA, F(AAM), BioFire: Grant/Research Support|Luminex: Grant/Research Support Mary A. Staat, MD, MPH, Centers for Disease Control and Prevention: Grant/Research Support|Cepheid: Grant/Research Support|National Institute of Health: Grant/Research Support|Uptodate: Royalties Geoffrey A. Weinberg, MD, Merck & Co.: Honoraria|Merck & Co.: Honoraria for composing and reviewing textbook chapters, Merck Manual of Therapeutics Flor M. Munoz, MD, MSc, Gilead: Grant/Research Support|Moderna: DSMB|Pfizer: DSMB Christopher J Harrison, MD, Astellas: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|Pediatric news: Honoraria|Pfizer: Grant/Research Support Natasha B. Halasa, MD, Quidel: Grant/Research Support|Quidel: equipment donation|Sanofi: Grant/Research Support|Sanofi: HAI testing and vaccine donation.

Comparative analysis of three multiplex platforms for the detection of respiratory viral pathogens

BACKGROUND

Acute viral respiratory infections are a major health burden in children worldwide. In recent years, rapid and sensitive multiplex nucleic acid amplification tests (NAATs) have replaced conventional methods for routine virus detection in the clinical laboratory.

OBJECTIVE/STUDY DESIGN

We compared BioFire® FilmArray® Respiratory Panel (FilmArray V1.7), Luminex NxTag® Respiratory Pathogen Panel (NxTag RPP) and Applied Biosystems TaqMan Array Card (TAC) for the detection of eight viruses in pediatric respiratory specimens. Results from the three platforms were analyzed with a single-plex real-time RT-PCR (rRT-PCR) assay for each virus.

RESULTS

Of the 170/210 single-plex virus-positive samples, FilmArray detected a virus in 166 (97.6%), TAC in 163 (95.8%) and NxTag RPP in 160 (94.1%) samples. The Positive Percent Agreement (PPA) of FilmArray, NxTag RPP and TAC was highest for influenza B (100%, 100% and 95.2% respectively) and lowest for seasonal coronaviruses on both FilmArray (90.2%) and NxTag RPP (81.8%), and for parainfluenza viruses 1- 4 on TAC (84%). The Negative Percent Agreement (NPA) was lowest for rhinovirus/enterovirus (92.9%, 96.7% and 97.3%) on FilmArray, NxTag RPP and TAC respectively. NPA for all three platforms was highest (100%) for both parainfluenza viruses 1- 4 and influenza A and B, and 100% for human metapneumovirus with TAC as well.

CONCLUSION

All three multiplex platforms displayed high overall agreement (&gt;90%) and high NPA (&gt;90%), while PPA was pathogen dependent and varied among platforms; high PPA (&gt;90%) was observed for FilmArray for all eight viruses, TAC for six viruses and NxTag RPP for 4 viruses.

Disease Progression of WHIM Syndrome in an International Cohort of 66 Pediatric and Adult Patients

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome (WS) is a combined immunodeficiency caused by gain-of-function mutations in the C-X-C chemokine receptor type 4 (CXCR4) gene. We characterize a unique international cohort of 66 patients, including 57 (86%) cases previously unreported, with variable clinical phenotypes. Of 17 distinct CXCR4 genetic variants within our cohort, 11 were novel pathogenic variants affecting 15 individuals (23%). All variants affect the same CXCR4 region and impair CXCR4 internalization resulting in hyperactive signaling. The median age of diagnosis in our cohort (5.5 years) indicates WHIM syndrome can commonly present in childhood, although some patients are not diagnosed until adulthood. The prevalence and mean age of recognition and/or onset of clinical manifestations within our cohort were infections 88%/1.6 years, neutropenia 98%/3.8 years, lymphopenia 88%/5.0 years, and warts 40%/12.1 years. However, we report greater prevalence and variety of autoimmune complications of WHIM syndrome (21.2%) than reported previously. Patients with versus without family history of WHIM syndrome were diagnosed earlier (22%, average age 1.3 years versus 78%, average age 5 years, respectively). Patients with a family history of WHIM syndrome also received earlier treatment, experienced less hospitalization, and had less end-organ damage. This observation reinforces previous reports that early treatment for WHIM syndrome improves outcomes. Only one patient died; death was attributed to complications of hematopoietic stem cell transplantation. The variable expressivity of WHIM syndrome in pediatric patients delays their diagnosis and therapy. Early-onset bacterial infections with severe neutropenia and/or lymphopenia should prompt genetic testing for WHIM syndrome, even in the absence of warts.

Clinical Presentation and Severity of Adenovirus Detection Alone vs Adenovirus Co-detection With Other Respiratory Viruses in US Children With Acute Respiratory Illness from 2016 to 2018

BACKGROUND

Human adenovirus (HAdV) is commonly associated with acute respiratory illnesses (ARI) in children and is also frequently co-detected with other viral pathogens. We compared clinical presentation and outcomes in young children with HAdV detected alone vs co-detected with other respiratory viruses.

METHODS

We used data from a multicenter, prospective, viral surveillance study of children seen in the emergency department and inpatient pediatric settings at seven US sites. Children less than 18 years old with fever and/or respiratory symptoms were enrolled between 12/1/16 and 10/31/18 and tested by molecular methods for HAdV, human rhinovirus/enterovirus (HRV/EV), respiratory syncytial virus (RSV), parainfluenza (PIV, types 1-4), influenza (flu, types A-C), and human metapneumovirus (HMPV). Our primary measure of illness severity was hospitalization; among hospitalized children, secondary severity outcomes included oxygen support and length of stay (LOS).

RESULTS

Of the 18,603 children enrolled, HAdV was detected in 1,136 (6.1%), among whom 646 (56.9%) had co-detection with at least one other respiratory virus. HRV/EV (n = 293, 45.3%) and RSV (n = 123, 19.0%) were the most frequent co-detections. Children with HRV/EV (aOR = 1.61; 95% CI = [1.11-2.34]), RSV (aOR = 4.48; 95% CI = [2.81-7.14]), HMPV (aOR = 3.39; 95% CI = [1.69-6.77]), or ≥ 2 co-detections (aOR = 1.95; 95% CI = [1.14-3.36]) had higher odds of hospitalization compared to children with HAdV alone. Among hospitalized children, HAdV co-detection with RSV or HMPV was each associated with higher odds of oxygen support, while co-detection with PIV or influenza viruses was each associated with higher mean LOS.

CONCLUSIONS

HAdV co-detection with other respiratory viruses was associated with greater disease severity among children with ARI compared to HAdV detection alone.

Respiratory Virus Surveillance Among Children with Acute Respiratory Illnesses - New Vaccine Surveillance Network, United States, 2016-2021

The New Vaccine Surveillance Network (NVSN) is a prospective, active, population-based surveillance platform that enrolls children with acute respiratory illnesses (ARIs) at seven pediatric medical centers. ARIs are caused by respiratory viruses including influenza virus, respiratory syncytial virus (RSV), human metapneumovirus (HMPV), human parainfluenza viruses (HPIVs), and most recently SARS-CoV-2 (the virus that causes COVID-19), which result in morbidity among infants and young children (1-6). NVSN estimates the incidence of pathogen-specific pediatric ARIs and collects clinical data (e.g., underlying medical conditions and vaccination status) to assess risk factors for severe disease and calculate influenza and COVID-19 vaccine effectiveness. Current NVSN inpatient (i.e., hospital) surveillance began in 2015, expanded to emergency departments (EDs) in 2016, and to outpatient clinics in 2018. This report describes demographic characteristics of enrolled children who received care in these settings, and yearly circulation of influenza, RSV, HMPV, HPIV1-3, adenovirus, human rhinovirus and enterovirus (RV/EV),* and SARS-CoV-2 during December 2016-August 2021. Among 90,085 eligible infants, children, and adolescents (children) aged <18 years^† with ARI, 51,441 (57%) were enrolled, nearly 75% of whom were aged <5 years; 43% were hospitalized. Infants aged <1 year accounted for the largest proportion (38%) of those hospitalized. The most common pathogens detected were RV/EV and RSV. Before the emergence of SARS-CoV-2, detected respiratory viruses followed previously described seasonal trends, with annual peaks of influenza and RSV in late fall and winter (7,8). After the emergence of SARS-CoV-2 and implementation of associated pandemic nonpharmaceutical interventions and community mitigation measures, many respiratory viruses circulated at lower-than-expected levels during April 2020-May 2021. Beginning in summer 2021, NVSN detected higher than anticipated enrollment of hospitalized children as well as atypical interseasonal circulation of RSV. Further analyses of NVSN data and continued surveillance are vital in highlighting risk factors for severe disease and health disparities, measuring the effectiveness of vaccines and monoclonal antibody-based prophylactics, and guiding policies to protect young children from pathogens such as SARS-CoV-2, influenza, and RSV.

Understanding Variation in Rotavirus Vaccine Effectiveness Estimates in the United States: The Role of Rotavirus Activity and Diagnostic Misclassification

BACKGROUND

Estimates of rotavirus vaccine effectiveness (VE) in the United States appear higher in years with more rotavirus activity. We hypothesized rotavirus VE is constant over time but appears to vary as a function of temporal variation in local rotavirus cases and/or misclassified diagnoses.

METHODS

We analyzed 6 years of data from eight US surveillance sites on 8- to 59-month olds with acute gastroenteritis symptoms. Children's stool samples were tested via enzyme immunoassay (EIA); rotavirus-positive results were confirmed with molecular testing at the US Centers for Disease Control and Prevention. We defined rotavirus gastroenteritis cases by either positive on-site EIA results alone or positive EIA with Centers for Disease Control and Prevention confirmation. For each case definition, we estimated VE against any rotavirus gastroenteritis, moderate-to-severe disease, and hospitalization using two mixed-effect regression models: the first including year plus a year-vaccination interaction, and the second including the annual percent of rotavirus-positive tests plus a percent positive-vaccination interaction. We used multiple overimputation to bias-adjust for misclassification of cases defined by positive EIA alone.

RESULTS

Estimates of annual rotavirus VE against all outcomes fluctuated temporally, particularly when we defined cases by on-site EIA alone and used a year-vaccination interaction. Use of confirmatory testing to define cases reduced, but did not eliminate, fluctuations. Temporal fluctuations in VE estimates further attenuated when we used a percent positive-vaccination interaction. Fluctuations persisted until bias-adjustment for diagnostic misclassification.

CONCLUSIONS

Both controlling for time-varying rotavirus activity and bias-adjusting for diagnostic misclassification are critical for estimating the most valid annual rotavirus VE.

Vaccine Effectiveness Against Influenza Hospitalization and Emergency Department Visits in 2 A(H3N2) Dominant Influenza Seasons Among Children <18 Years Old-New Vaccine Surveillance Network 2016-2017 and 2017-2018

Studies have shown egg-adaptive mutations in influenza vaccine strains that might have impaired protection against circulating A(H3N2) influenza viruses during the 2016-2017 and 2017-2018 seasons. We used the test-negative design and multivariable models to assess vaccine effectiveness against influenza-associated hospitalization and emergency department visits among children (<18 years old) during the 2016-2017 and 2017-2018 seasons. Effectiveness was 71% (95% confidence interval, 59%-79%), 46% (35%-55%), and 45% (33%-55%) against A(H1N1)pdm09, A(H3N2), and B viruses respectively, across both seasons. During high-severity seasons with concerns for vaccine mismatch, vaccination offered substantial protection against severe influenza outcomes requiring hospitalization or emergency department visits among children.

Influenza clinical testing and oseltamivir treatment in hospitalized children with acute respiratory illness, 2015-2016

BACKGROUND

Antiviral treatment is recommended for all hospitalized children with suspected or confirmed influenza, regardless of their risk profile. Few data exist on adherence to these recommendations, so we sought to determine factors associated with influenza testing and antiviral treatment in children.

METHODS

Hospitalized children <18 years of age with acute respiratory illness (ARI) were enrolled through active surveillance at pediatric medical centers in seven cities between 11/1/2015 and 6/30/2016; clinical information was obtained from parent interview and chart review. We used generalized linear mixed-effects models to identify factors associated with influenza testing and antiviral treatment.

RESULTS

Of the 2299 hospitalized children with ARI enrolled during one influenza season, 51% (n = 1183) were tested clinically for influenza. Clinicians provided antiviral treatment for 61 of 117 (52%) patients with a positive influenza test versus 66 of 1066 (6%) with a negative or unknown test result. In multivariable analyses, factors associated with testing included neuromuscular disease (aOR = 5.35, 95% CI [3.58-8.01]), immunocompromised status (aOR = 2.88, 95% CI [1.66-5.01]), age (aOR = 0.93, 95% CI [0.91-0.96]), private only versus public only insurance (aOR = 0.78, 95% CI [0.63-0.98]), and chronic lung disease (aOR = 0.64, 95% CI [0.51-0.81]). Factors associated with antiviral treatment included neuromuscular disease (aOR = 1.86, 95% CI [1.04, 3.31]), immunocompromised state (aOR = 2.63, 95% CI [1.38, 4.99]), duration of illness (aOR = 0.92, 95% CI [0.84, 0.99]), and chronic lung disease (aOR = 0.60, 95% CI [0.38, 0.95]).

CONCLUSION

Approximately half of children hospitalized with influenza during the 2015-2016 influenza season were treated with antivirals. Because antiviral treatment for influenza is associated with better health outcomes, further studies of subsequent seasons would help evaluate current use of antivirals among children and better understand barriers for treatment.

154. Circulation of Rhinovirus/Enterovirus Respiratory Infections in Children During 2020-21 in the United States

Background

Sharp declines in influenza and respiratory syncytial virus (RSV) circulation across the U.S. have been described during the pandemic in temporal association with community mitigation for control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to determine relative frequencies of rhinovirus/enterovirus (RV/EV) and other respiratory viruses in children presenting to emergency departments or hospitalized with acute respiratory illness (ARI) prior to and during the COVID-19 pandemic.

Methods

We conducted a multi-center active prospective ARI surveillance study in children as part of the New Vaccine Surveillance Network (NVSN) from December 2016 through January 2021. Molecular testing for RV/EV, RSV, influenza, and other respiratory viruses [i.e., human metapneumovirus, parainfluenza virus (Types 1-4), and adenovirus] were performed on specimens collected from children enrolled children. Cumulative percent positivity of each virus type during March 2020–January 2021 was compared from March-January in the prior seasons (2017-2018, 2018-2019, 2019-2020) using Pearson’s chi-squared. Data are provisional.

Results

Among 69,403 eligible children, 37,676 (54%) were enrolled and tested for respiratory viruses. The number of both eligible and enrolled children declined in early 2020 (Figure 1), but 4,691 children (52% of eligible) were enrolled and tested during March 2020-January 2021. From March 2020-January 2021, the overall percentage of enrolled children with respiratory testing who had detectable RV/EV was similar compared to the same time period in 2017-2018 and 2019-2020 (Figure 1, Table 1). In contrast, the percent positivity of RSV, influenza, and other respiratory viruses combined declined compared to prior years, (p< 0.001, Figure 1, Table 1).

Figure 1. Percentage of Viral Detection Among Enrolled Children Who Received Respiratory Testing, New Vaccine Surveillance Network (NVSN), United States, December 2016 – January 2021

Table 1. Percent of Respiratory Viruses Circulating in March 2020– January 2021, compared to March-January in Prior Years, New Vaccine Surveillance Network (NVSN), United States, March 2017 – January 2021

Conclusion

During 2020, RV/EV continued to circulate among children receiving care for ARI despite abrupt declines in other respiratory viruses within this population. These findings warrant further studies to understand virologic, behavioral, biological, and/or environmental factors associated with this continued RV/EV circulation.

Disclosures

Jennifer E. Schuster, MD, Merck, Sharpe, and Dohme (Individual(s) Involved: Self): Grant/Research Support Marian G. Michaels, MD, MPH, Viracor (Grant/Research Support, performs assay for research study no financial support) John V. Williams, MD, GlaxoSmithKline (Advisor or Review Panel member, Independent Data Monitoring Committee)Quidel (Advisor or Review Panel member, Scientific Advisory Board) Elizabeth P. Schlaudecker, MD, MPH, Pfizer (Grant/Research Support)Sanofi Pasteur (Advisor or Review Panel member) Christopher J. Harrison, MD, GSK (Grant/Research Support)Merck (Grant/Research Support)Pfizer (Grant/Research Support, Scientific Research Study Investigator, Research Grant or Support) Janet A. Englund, MD, AstraZeneca (Consultant, Grant/Research Support)GlaxoSmithKline (Research Grant or Support)Meissa Vaccines (Consultant)Pfizer (Research Grant or Support)Sanofi Pasteur (Consultant)Teva Pharmaceuticals (Consultant) Claire Midgley, PhD, Nothing to disclose Natasha B. Halasa, MD, MPH, Genentech (Other Financial or Material Support, I receive an honorarium for lectures - it’s a education grant, supported by genetech)Quidel (Grant/Research Support, Other Financial or Material Support, Donation of supplies/kits)Sanofi (Grant/Research Support, Other Financial or Material Support, HAI/NAI testing) Natasha B. Halasa, MD, MPH, Genentech (Individual(s) Involved: Self): I receive an honorarium for lectures - it’s a education grant, supported by genetech, Other Financial or Material Support, Other Financial or Material Support; Sanofi (Individual(s) Involved: Self): Grant/Research Support, Research Grant or Support

1178. Sustained Vaccine Effectiveness Against Influenza-Associated Hospitalization in Children: Evidence from the New Vaccine Surveillance Network, 2015-2016 Through 2019-2020

Background

Adult studies have demonstrated intra-season declines in influenza vaccine effectiveness (VE) with increasing time since vaccination; however, data in children are limited.

Methods

We conducted a prospective, test-negative study of children ages 6 months through 17 years hospitalized with acute respiratory illness at 7 pediatric medical centers each season in the New Vaccine Surveillance Network during the 2015-2016 through 2019-2020 influenza seasons. Cases were children with an influenza-positive molecular test; controls were influenza-negative children. Controls were matched to cases by illness onset date using 3:1 nearest neighbor matching. We estimated VE [100% x (1 – odds ratio)] by comparing the odds of receipt of ≥ 1 dose of influenza vaccine ≥ 14 days before the onset of illness that resulted in hospitalization among influenza-positive children to influenza-negative children. Changes in VE over time between vaccination date and illness onset date during each season were estimated using multivariable logistic regression models.

Results

Of 8,430 hospitalized children (4,781 [57%] male; median age 2.4 years), 4,653 (55%) received ≥ 1 dose of influenza vaccine. On average, 48% and 85% of children were vaccinated by the end of October and December, respectively. Influenza-positive cases (n=1,000; 12%) were less likely to be vaccinated than influenza-negative controls (39% vs. 61%, p&lt; 0.001) and overall VE against hospitalization was 53% (95% CI: 46%, 60%). Pooling data across 5 seasons, the odds of any influenza-associated hospitalization increased 0.96% (95% CI: -0.76%, 2.71%) per week with a corresponding weekly decrease in VE of 0.45% (p=0.275). Odds of hospitalization with time since vaccination increased 0.66% (95% CI: -0.76%, 2.71%) per week in children ≤ 8 years (n=3,084) and 2.16% (95% CI: -1.68%, 6.15%) per week in children 9-17 years (n=771). No significant differences were observed by virus subtype or lineage.

Figure 1. Declines in influenza VE over time from 2015-2016 through 2019-2020, overall (a) and by age group (b: ≤ 8 years; c: 9-17 years)

Conclusion

We observed minimal intra-season declines in VE against influenza-associated hospitalization in U.S. children. Vaccination following Advisory Committee on Immunization Practices guidelines and current timing of vaccine receipt is the best strategy for prevention of influenza-associated hospitalization in children.

Disclosures

Marian G. Michaels, MD, MPH, Viracor (Grant/Research Support, performs assay for research study no financial support) John V. Williams, MD, GlaxoSmithKline (Advisor or Review Panel member, Independent Data Monitoring Committee)Quidel (Advisor or Review Panel member, Scientific Advisory Board) Elizabeth P. Schlaudecker, MD, MPH, Pfizer (Grant/Research Support)Sanofi Pasteur (Advisor or Review Panel member) Natasha B. Halasa, MD, MPH, Genentech (Other Financial or Material Support, I receive an honorarium for lectures - it’s a education grant, supported by genetech)Quidel (Grant/Research Support, Other Financial or Material Support, Donation of supplies/kits)Sanofi (Grant/Research Support, Other Financial or Material Support, HAI/NAI testing) Natasha B. Halasa, MD, MPH, Genentech (Individual(s) Involved: Self): I receive an honorarium for lectures - it’s a education grant, supported by genetech, Other Financial or Material Support, Other Financial or Material Support; Sanofi (Individual(s) Involved: Self): Grant/Research Support, Research Grant or Support Janet A. Englund, MD, AstraZeneca (Consultant, Grant/Research Support)GlaxoSmithKline (Research Grant or Support)Meissa Vaccines (Consultant)Pfizer (Research Grant or Support)Sanofi Pasteur (Consultant)Teva Pharmaceuticals (Consultant) Christopher J. Harrison, MD, GSK (Grant/Research Support)Merck (Grant/Research Support)Pfizer (Grant/Research Support, Scientific Research Study Investigator, Research Grant or Support) Flor M. Munoz, MD, Biocryst (Scientific Research Study Investigator)Gilead (Scientific Research Study Investigator)Meissa (Other Financial or Material Support, DSMB)Moderna (Scientific Research Study Investigator, Other Financial or Material Support, DSMB)Pfizer (Scientific Research Study Investigator, Other Financial or Material Support, DSMB)Virometix (Other Financial or Material Support, DSMB)

Enterovirus D68-Associated Acute Respiratory Illness ─ New Vaccine Surveillance Network, United States, July-November 2018-2020

Enterovirus D68 (EV-D68) is associated with a broad spectrum of illnesses, including mild to severe acute respiratory illness (ARI) and acute flaccid myelitis (AFM). Enteroviruses, including EV-D68, are typically detected in the United States during late summer through fall, with year-to-year fluctuations. Before 2014, EV-D68 was infrequently reported to CDC (1). However, numbers of EV-D68 detection have increased in recent years, with a biennial pattern observed during 2014-2018 in the United States, after the expansion of surveillance and wider availability of molecular testing. In 2014, a national outbreak of EV-D68 was detected (2). EV-D68 was also reported in 2016 via local (3) and passive national (4) surveillance. EV-D68 detections were limited in 2017, but substantial circulation was observed in 2018 (5). To assess recent levels of circulation, EV-D68 detections in respiratory specimens collected from patients aged <18 years* with ARI evaluated in emergency departments (EDs) or admitted to one of seven U.S. medical centers^† within the New Vaccine Surveillance Network (NVSN) were summarized. This report provides a provisional description of EV-D68 detections during July-November in 2018, 2019 and 2020, and describes the demographic and clinical characteristics of these patients. In 2018, a total of 382 EV-D68 detections in respiratory specimens obtained from patients aged <18 years with ARI were reported by NVSN; the number decreased to six detections in 2019 and 30 in 2020. Among patients aged <18 years with EV-D68 in 2020, 22 (73%) were non-Hispanic Black (Black) persons. EV-D68 detections in 2020 were lower than anticipated based on the biennial circulation pattern observed since 2014. The circulation of EV-D68 in 2020 might have been limited by widespread COVID-19 mitigation measures; how these changes in behavior might influence the timing and levels of circulation in future years is unknown. Ongoing monitoring of EV-D68 detections is warranted for preparedness for EV-D68-associated ARI and AFM.

Clinical Influenza Testing Practices in Hospitalized Children at United States Medical Centers, 2015-2018

At nine US hospitals that enrolled children hospitalized with acute respiratory illness (ARI) during 2015-2016 through 2017-2018 influenza seasons, 50% of children with ARI received clinician-initiated testing for influenza and 35% of cases went undiagnosed due to lack of clinician-initiated testing. Marked heterogeneity in testing practice was observed across sites.

Effect of Vaccination on Preventing Influenza-Associated Hospitalizations Among Children During a Severe Season Associated With B/Victoria Viruses, 2019-2020

BACKGROUND

The 2019-2020 influenza season was characterized by early onset with B/Victoria followed by A(H1N1)pdm09 viruses. Emergence of new B/Victoria viruses raised concerns about possible vaccine mismatch. We estimated vaccine effectiveness (VE) against influenza-associated hospitalizations and emergency department (ED) visits among children in the United States.

METHODS

We assessed VE among children aged 6 months-17 years with acute respiratory illness and ≤10 days of symptoms enrolled at 7 pediatric medical centers in the New Vaccine Surveillance Network. Combined midturbinate/throat swabs were tested for influenza virus using molecular assays. Vaccination history was collected from parental report, state immunization information systems, and/or provider records. We estimated VE from a test-negative design using logistic regression to compare odds of vaccination among children testing positive vs negative for influenza.

RESULTS

Among 2029 inpatients, 335 (17%) were influenza positive: 37% with influenza B/Victoria alone and 44% with influenza A(H1N1)pdm09 alone. VE was 62% (95% confidence interval [CI], 52%-71%) for influenza-related hospitalizations, 54% (95% CI, 33%-69%) for B/Victoria viruses, and 64% (95% CI, 49%-75%) for A(H1N1)pdm09. Among 2102 ED patients, 671 (32%) were influenza positive: 47% with influenza B/Victoria alone and 42% with influenza A(H1N1)pdm09 alone. VE was 56% (95% CI, 46%-65%) for an influenza-related ED visit, 55% (95% CI, 40%-66%) for B/Victoria viruses, and 53% (95% CI, 37%-65%) for A(H1N1)pdm09.

CONCLUSIONS

Influenza vaccination provided significant protection against laboratory-confirmed influenza-associated hospitalizations and ED visits associated with the 2 predominantly circulating influenza viruses among children, including against the emerging B/Victoria virus subclade.

Acute Respiratory Illnesses in Children in the SARS-CoV-2 Pandemic: Prospective Multicenter Study

OBJECTIVES

Nonpharmaceutical interventions against coronavirus disease 2019 likely have a role in decreasing viral acute respiratory illnesses (ARIs). We aimed to assess the frequency of respiratory syncytial virus (RSV) and influenza ARIs before and during the coronavirus disease 2019 pandemic.

METHODS

This study was a prospective, multicenter, population-based ARI surveillance, including children seen in the emergency departments and inpatient settings in 7 US cities for ARI. Respiratory samples were collected and evaluated by molecular testing. Generalized linear mixed-effects models were used to evaluate the association between community mitigation and number of eligible and proportion of RSV and influenza cases.

RESULTS

Overall, 45 759 children were eligible; 25 415 were enrolled and tested; 25% and 14% were RSV-positive and influenza-positive, respectively. In 2020, we noted a decrease in eligible and enrolled ARI subjects after community mitigation measures were introduced, with no RSV or influenza detection from April 5, 2020, to April 30, 2020. Compared with 2016-2019, there was an average of 10.6 fewer eligible ARI cases per week per site and 63.9% and 45.8% lower odds of patients testing positive for RSV and influenza, respectively, during the 2020 community mitigation period. In all sites except Seattle, the proportions of positive tests for RSV and influenza in the 2020 community mitigation period were lower than predicted.

CONCLUSIONS

Between March and April 2020, rapid declines in ARI cases and the proportions of RSV and influenza in children were consistently noted across 7 US cities, which could be attributable to community mitigation measures against severe acute respiratory syndrome coronavirus 2.

Comparison of Parental Report of Influenza Vaccination to Documented Records in Children Hospitalized With Acute Respiratory Illness, 2015-2016

BACKGROUND

Parent-reported influenza vaccination history may be valuable clinically and in influenza vaccine effectiveness (VE) studies. Few studies have assessed the validity of parental report among hospitalized children.

METHODS

Parents of 2597 hospitalized children 6 months-17 years old were interviewed from November 1, 2015 to June 30, 2016, regarding their child's sociodemographic and influenza vaccination history. Parent-reported 2015-2016 influenza vaccination history was compared with documented vaccination records (considered the gold standard for analysis) obtained from medical records, immunization information systems, and providers. Multivariable logistic regression analyses were conducted to determine potential factors associated with discordance between the 2 sources of vaccination history. Using a test-negative design, we estimated VE using vaccination history obtained through parental report and documented records.

RESULTS

According to parental report, 1718 (66%) children received the 2015-2016 influenza vaccine, and of those, 1432 (83%) had documentation of vaccine receipt. Percent agreement was 87%, with a sensitivity of 96% (95% confidence interval [CI], 95%-97%) and a specificity of 74% (95% CI, 72%-77%). In the multivariable logistic regression, study site and child's age 5-8 years were significant predictors of discordance. Adjusted VE among children who received ≥1 dose of the 2015-2016 influenza vaccine per parental report was 61% (95% CI, 43%-74%), whereas VE using documented records was 55% (95% CI, 33%-69%).

CONCLUSIONS

Parental report of influenza vaccination was sensitive but not as specific compared with documented records. However, VE against influenza-associated hospitalizations using either source of vaccination history did not differ substantially. Parental report is valuable for timely influenza VE studies.

Rotavirus Genotype Trends and Gastrointestinal Pathogen Detection in the United States, 2014-16: Results from the New Vaccine Surveillance Network

BACKGROUND

Following the implementation of rotavirus vaccination in 2006, severe acute gastroenteritis (AGE) due to group A rotavirus (RVA) has substantially declined in USA (US) children. We report the RVA genotype prevalence as well as co-infection data from seven US New Vaccine Surveillance Network (NVSN) sites during three consecutive RVA seasons, 2014-2016.

METHODS

A total of 1041 stool samples that tested positive for RVA by Rotaclone enzyme immunoassay (EIA) were submitted to the Centers for Disease Control and Prevention (CDC) for RVA genotyping and multipathogen testing.

RESULTS

A total of 795 (76%) contained detectable RVA at CDC. Rotavirus disease was highest in children < 3 years of age. Four G types (G1, G2, G9, and G12) accounted for 94.6% of strains while two P types (P[4] and P[8]) accounted 94.7% of the strains. Overall, G12P[8] was the most common genotype detected in all three seasons. Stepwise conditional logistic analysis found year and study site were significant predictors of genotype. Twenty four percent (24%) of RVA-positive specimens contained other AGE pathogens.

CONCLUSIONS

G12P[8] predominated over three seasons, but strain predominance varied by year and study site. Ongoing surveillance provides continuous tracking and monitoring of US genotypes during the post vaccine era.

Vaccine Effectiveness Against Influenza Hospitalization Among Children in the United States, 2015-2016

BACKGROUND

Annual United States (US) estimates of influenza vaccine effectiveness (VE) in children typically measure protection against outpatient medically attended influenza illness, with limited data evaluating VE against influenza hospitalizations. We estimated VE for preventing laboratory-confirmed influenza hospitalization among US children.

METHODS

We included children aged 6 months-17 years with acute respiratory illness enrolled in the New Vaccine Surveillance Network during the 2015-2016 influenza season. Documented influenza vaccination status was obtained from state immunization information systems, the electronic medical record, and/or provider records. Midturbinate nasal and throat swabs were tested for influenza using molecular assays. We estimated VE as 100% × (1 - odds ratio), comparing the odds of vaccination among subjects testing influenza positive with subjects testing negative, using multivariable logistic regression.

RESULTS

Of 1653 participants, 36 of 707 (5%) of those fully vaccinated, 18 of 226 (8%) of those partially vaccinated, and 85 of 720 (12%) of unvaccinated children tested positive for influenza. Of those vaccinated, almost 90% were documented to have received inactivated vaccine. The majority (81%) of influenza cases were in children ≤ 8 years of age. Of the 139 influenza-positive cases, 42% were A(H1N1)pdm09, 42% were B viruses, and 14% were A(H3N2). Overall, adjusted VE for fully vaccinated children was 56% (95% confidence interval [CI], 34%-71%) against any influenza-associated hospitalization, 68% (95% CI, 36%-84%) for A(H1N1)pdm09, and 44% (95% CI, -1% to 69%) for B viruses.

CONCLUSIONS

These findings demonstrate the importance of annual influenza vaccination in prevention of severe influenza disease and of reducing the number of children who remain unvaccinated or partially vaccinated against influenza.

Comparative genomic analysis of genogroup 1 and genogroup 2 rotaviruses circulating in seven US cities, 2014-2016

For over a decade, the New Vaccine Surveillance Network (NVSN) has conducted active rotavirus (RVA) strain surveillance in the USA. The evolution of RVA in the post-vaccine introduction era and the possible effects of vaccine pressure on contemporary circulating strains in the USA are still under investigation. Here, we report the whole-gene characterization (eleven ORFs) for 157 RVA strains collected at seven NVSN sites during the 2014 through 2016 seasons. The sequenced strains included 52 G1P[8], 47 G12P[8], 18 G9P[8], 24 G2P[4], 5 G3P[6], as well as 7 vaccine strains, a single mixed strain (G9G12P[8]), and 3 less common strains. The majority of the single and mixed strains possessed a Wa-like backbone with consensus genotype constellation of G1/G3/G9/G12-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1, while the G2P[4], G3P[6], and G2P[8] strains displayed a DS-1-like genetic backbone with consensus constellation of G2/G3-P[4]/P[6]/P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Two intergenogroup reassortant G1P[8] strains were detected that appear to be progenies of reassortment events between Wa-like G1P[8] and DS-1-like G2P[4] strains. Two Rotarix^® vaccine (RV1) and two RV5 derived (vd) reassortant strains were detected. Phylogenetic and similarity matrices analysis revealed 2-11 sub-genotypic allelic clusters among the genes of Wa- and DS-1-like strains. Most study strains clustered into previously defined alleles. Amino acid (AA) substitutions occurring in the neutralization epitopes of the VP7 and VP4 proteins characterized in this study were mostly neutral in nature, suggesting that these RVA proteins were possibly under strong negative or purifying selection in order to maintain competent and actual functionality, but fourteen radical (AA changes that occur between groups) AA substitutions were noted that may allow RVA strains to gain a selective advantage through immune escape. The tracking of RVA strains at the sub-genotypic allele constellation level will enhance our understanding of RVA evolution under vaccine pressure, help identify possible mechanisms of immune escape, and provide valuable information for formulation of future RVA vaccines.

78. Acute Respiratory Illnesses in Children During the sars-cov-2 Pandemic: A Prospective Multicenter Surveillance Study

Background

A state of emergency was declared in the United States (US) on March 13, 2020 in response to the SARS-CoV-2 pandemic. Healthcare providers had to alter practice patterns and research priorities. We assessed the frequency of acute respiratory illnesses (ARI) in children, notably those due to respiratory syncytial virus (RSV) and influenza, before and during the pandemic.

Methods

We conducted multi-center active prospective ARI surveillance in children as part of the New Vaccine Surveillance Network. Children < 18 years with fever and/or respiratory symptoms were enrolled in emergency department and inpatient settings at seven US medical centers over four respiratory seasons during 2016–2020 (Fig 1). Pandemic-related restrictions to patient access limited enrollment in some sites beginning March 2020. Respiratory specimens were collected and tested at each site for RSV and influenza by qRT-PCR. Data were analyzed by calendar weeks. We compared the cumulative proportions of RSV and influenza detection after week 13 in 2020 to the previous seasons using Fisher’s exact test.

Figure 1. Numbers of Eligible and Enrolled Acute Respiratory Illness Cases, and Proportions of RSV and Influenza Detection by Week, Stratified by Study Season

Results

Of 44,247 eligible children, 25,375 (57%) were enrolled and tested for RSV and/or influenza. A total of 6351/25375 (25%) and 3446/25372 (14%) children were RSV and influenza-positive over the four seasons, respectively. In 2020, we noted a rapid drop in eligible and enrolled ARI subjects after weeks 11–13 (Fig 1). During weeks 13–18 in 2016–2019, the three-year average of eligible and enrolled subjects was 1802 and 978, respectively. However, over the same period in 2020, there were 675 eligible and 278 enrolled subjects, representing declines of 62.5% and 71.6% respectively (Fig 1). In 2020, there were no RSV or influenza cases detected in weeks 15–18, and the cumulative proportions of RSV and influenza detection after week 13 were lower compared to previous seasons (p< 0.001) (Figs 1 and 2).

Figure 2. Cumulative Proportions of Weekly RSV and Influenza Detection by Study Season

Conclusion

There was a considerable decline in ARI visits and the proportion of RSV and influenza detection across seven distinct geographic sites during the pandemic compared with previous seasons. These findings might be attributable to social distancing measures to lessen the spread of SARS-CoV-2, changes in healthcare-seeking behaviors, and limited access to medical care.

Disclosures

Zaid Haddadin, MD, CDC (Grant/Research Support, Research Grant or Support)Quidel Corporation (Grant/Research Support, Research Grant or Support)sanofi pasteur (Grant/Research Support, Research Grant or Support) John V. Williams, MD, GlaxoSmithKline (Advisor or Review Panel member)IDConnect (Advisor or Review Panel member)Quidel (Advisor or Review Panel member) Christopher J. Harrison, MD, GSK (Grant/Research Support, Infant menigiciccal B conjugate vaccine trial)Merck (Research Grant or Support, Infant pneumococcal conjugate vaccine trial) Janet A. Englund, MD, AstraZeneca (Scientific Research Study Investigator)GSK group of companies (Scientific Research Study Investigator)Meissa vaccines (Consultant)Merck (Scientific Research Study Investigator)Sanofi Pasteur (Consultant) Natasha B. Halasa, MD, MPH, Genentech (Other Financial or Material Support, I receive an honorarium for lectures - it’s a education grant, supported by genetech)Karius (Consultant)Moderna (Consultant)Quidel (Grant/Research Support, Research Grant or Support)Sanofi (Grant/Research Support, Research Grant or Support)

178. Vaccine Effectiveness Against Influenza-associated Hospitalizations and Emergency Department (ED) Visits Among Children in the United States in the 2019–2020 Season

Background

The 2019–20 influenza season was predominated by early onset B/Victoria viruses followed by A(H1N1)pdm09 virus circulation. Over 95% of circulating B/Victoria viruses were subclade V1A.3, different from the Northern Hemisphere vaccine strain. Annual estimates of influenza vaccine effectiveness (VE) are important because of frequent changes in circulating and vaccine viruses.

Methods

We assessed VE among children 6 months–17 years old with acute respiratory illness and <10 days of symptoms enrolled during the 2019–20 influenza season at 7 pediatric hospitals (ED patients < 5 years at 3 sites) in the New Vaccine Surveillance Network. Combined mid-turbinate/throat swabs were tested for influenza virus using molecular assays. We estimated age-stratified VE from a test-negative design using logistic regression to compare odds of vaccination among children testing positive versus negative for influenza, adjusting for age in years, enrollment month, and site. For these preliminary analyses, vaccination status was by parental report.

Results

Among 2022 inpatients, 324 (16%) were influenza positive: 38% with influenza B/Victoria alone and 44% with influenza A(H1N1)pdm09 alone (Table). Among 2066 ED children, 653 (32%) were influenza positive: 45% with influenza B/Victoria alone and 43% with influenza A(H1N1)pdm09 alone. VE was 62% (95% confidence interval [CI], 51%–70%) against any influenza-related hospitalizations, 68% (95% CI, 55%–78%) for A(H1N1)pdm09 and 55% (95% CI, 35%–69%) for B/Victoria. VE by age group for any influenza-related hospitalizations was 57% (95% CI, 40%–69%) among children 6 months to < 5 years and 66% (95% CI, 49%–77%) among children 5–17 years. VE was 53% (95% CI, 42%–62%) against any influenza-related ED visits, 46% (95% CI, 28%–60%) for A(H1N1)pdm09 and 54% (95% CI, 39%–66%) for B/Victoria. VE by age group was 52% (95% CI, 37%–63%) among children 6 months to < 5 years and 42% (95% CI, 16%–60%) among children 5–17 years.

Conclusion

Influenza vaccination in the 2019–20 season provided substantial protection against laboratory-confirmed influenza-associated hospitalizations and ED visits associated with the two predominantly circulating influenza viruses among children, including against the emerging B/Victoria virus V1A.3 subclade.

Disclosures

Janet A. Englund, MD, AstraZeneca (Scientific Research Study Investigator)GSK group of companies (Scientific Research Study Investigator)Meissa vaccines (Consultant)Merck (Scientific Research Study Investigator)Sanofi Pasteur (Consultant) John V. Williams, MD, GlaxoSmithKline (Advisor or Review Panel member)IDConnect (Advisor or Review Panel member)Quidel (Advisor or Review Panel member) Natasha B. Halasa, MD, MPH, Genentech (Other Financial or Material Support, I receive an honorarium for lectures - it’s a education grant, supported by genetech)Karius (Consultant)Moderna (Consultant)Quidel (Grant/Research Support, Research Grant or Support)Sanofi (Grant/Research Support, Research Grant or Support) Christopher J. Harrison, MD, GSK (Grant/Research Support, Infant menigiciccal B conjugate vaccine trial)Merck (Research Grant or Support, Infant pneumococcal conjugate vaccine trial)

1714. Influenza C Virus in U.S. Children with Acute Respiratory Infection 2016-2019

Background

Influenza C virus (ICV) is associated with acute respiratory infection (ARI); however, the burden of ICV is not well-described. We sought to determine the burden and characteristics of ICV in a prospective, population-based cohort.

Methods

The study was conducted within the New Vaccine Surveillance Network (NVSN), a CDC-led, seven-site network that performs population-based surveillance for ARI in children < 5 years. Nasal/throat swabs were collected from emergency department (ED) or inpatient children with ARI, or healthy controls in clinic, between 12/05/2016-10/31/2019 and tested by real-time RT-PCR for ICV and other respiratory viruses. Preliminary data were extracted and demographic/clinical features of ICV+ cases analyzed. We sequenced the hemagglutinin-esterase (HE) gene from ICV+ Pittsburgh samples.

Results

Among 19,321 children with ARI or healthy controls enrolled and tested for ICV from 2016-2019, 115/17,668 (0.7%) ARI cases and 8/1653 (0.5%) healthy controls tested positive for ICV. The median age of ICV+ ARI subjects was 19 months (IQR 10,46) and 81(70%) were ≤36 months. 42.6% (49) were white, 33.9% (39) black, and 16.5% (19) Hispanic, with the remainder Asian or unknown; 56.5% (62) attended daycare. Among ICV+ ARI cases, 67.8% (78) had fever, 94.8% (109) cough, and 60.8% (70) wheezing. 45.2% (52) ICV+ cases occurred in 2016-17, 6.5% (8) in 2017-2018, and 47.8% (55) in 2018-19 (Table). 40% (46) of ICV+ cases were seen in the ED, while the remainder were inpatients. Median length of stay was 2d (IQR,1-3) with 15 admitted to ICU. 67.8% (78/115) ARI cases had 1 or 2 co-detected pathogens, with rhinovirus (26), respiratory syncytial virus (26), and adenovirus (14) most frequently co-detected. ARI symptoms including fever, myalgias, chills, and wheezing did not differ significantly between coinfected subjects and those who were only ICV+. HE sequences were in the two currently circulating Kanagawa and Sao Paulo lineages.

ICV+ Cases by Site and Year

Conclusion

ICV was an uncommon cause of ARI symptoms leading to healthcare encounters in young children. The prevalence varied year-to-year and between different geographic regions. Most children infected with ICV were ≤3 years old and had co-detected pathogens. ICV was similarly rarely detected in healthy controls.

Disclosures

Christopher J. Harrison, MD, GSK (Grant/Research Support, Infant menigiciccal B conjugate vaccine trial)Merck (Research Grant or Support, Infant pneumococcal conjugate vaccine trial) Natasha B. Halasa, MD, MPH, Genentech (Other Financial or Material Support, I receive an honorarium for lectures - it’s a education grant, supported by genetech)Karius (Consultant)Moderna (Consultant)Quidel (Grant/Research Support, Research Grant or Support)Sanofi (Grant/Research Support, Research Grant or Support) John V. Williams, MD, GlaxoSmithKline (Advisor or Review Panel member)IDConnect (Advisor or Review Panel member)Quidel (Advisor or Review Panel member)

Continued Evidence of the Impact of Rotavirus Vaccine in Children Less Than 3 Years of Age From the United States New Vaccine Surveillance Network: A Multisite Active Surveillance Program, 2006-2016

BACKGROUND

Since 2006, the New Vaccine Surveillance Network has conducted active, population-based surveillance for acute gastroenteritis (AGE) hospitalizations and emergency department (ED) visits in 3 United States counties. Trends in the epidemiology and disease burden of rotavirus hospitalizations and ED visits were examined from 2006 to 2016.

METHODS

Children < 3 years of age hospitalized or visiting the ED with AGE were enrolled from January 2006 through June 2016. Bulk stool specimens were collected and tested for rotavirus. Rotavirus-associated hospitalization and ED visit rates were calculated annually with 2006-2007 defined as the prevaccine period and 2008-2016 as the postvaccine period. Rotavirus genotype trends were compared over time.

RESULTS

Over 11 seasons, 6954 children with AGE were enrolled and submitted a stool specimen (2187 hospitalized and 4767 in the ED). Comparing pre- and postvaccine periods, the proportion of children with rotavirus dramatically declined for hospitalization (49% vs 10%) and ED visits (49% vs 8%). In the postvaccine era, a biennial pattern of rotavirus rates was observed, with a trend toward an older median age. G1P[8] (63%) was the predominant genotype in the prevaccine period with a significantly lower proportion (7%) in the postvaccine period (P < .001). G2P[4] remained stable (8% to 14%) in both periods, whereas G3P[8] and G12P[8] increased in proportion from pre- to postvaccine periods (1% to 25% and 17% to 40%), respectively.

CONCLUSIONS

The epidemiology and disease burden of rotavirus has been altered by rotavirus vaccination with a biennial disease pattern, sustained low rates of rotavirus in children < 3 years of age, and a shift in the residual genotypes from G1P[8] to other genotypes.

Vaccine Effectiveness Against Pediatric Influenza Hospitalizations and Emergency Visits

BACKGROUND

Influenza A(H1N1)pdm09 viruses initially predominated during the US 2018-2019 season, with antigenically drifted influenza A(H3N2) viruses peaking later. We estimated vaccine effectiveness (VE) against laboratory-confirmed influenza-associated hospitalizations and emergency department (ED) visits among children in the New Vaccine Surveillance Network.

METHODS

We tested children 6 months to 17 years with acute respiratory illness for influenza using molecular assays at 7 pediatric hospitals (ED patients <5 years at 3 sites). Vaccination status sources were parental report, state immunization information systems and/or provider records for inpatients, and parental report alone for ED patients. We estimated VE using a test-negative design, comparing odds of vaccination among children testing positive versus negative for influenza using multivariable logistic regression.

RESULTS

Of 1792 inpatients, 226 (13%) were influenza-positive: 47% for influenza A(H3N2), 36% for A(H1N1)pdm09, 9% for A (not subtyped), and 7% for B viruses. Among 1944 ED children, 420 (22%) were influenza-positive: 48% for A(H3N2), 35% for A(H1N1)pdm09, 11% for A (not subtyped), and 5% for B viruses. VE was 41% (95% confidence interval [CI], 20% to 56%) against any influenza-related hospitalizations, 41% (95% CI, 11% to 61%) for A(H3N2), and 47% (95% CI, 16% to 67%) for A(H1N1)pdm09. VE was 51% (95% CI, 38% to 62%) against any influenza-related ED visits, 39% (95% CI, 15% to 56%) against A(H3N2), and 61% (95% CI, 44% to 73%) against A(H1N1)pdm09.

CONCLUSIONS

The 2018-2019 influenza vaccine reduced pediatric influenza A-associated hospitalizations and ED visits by 40% to 60%, despite circulation of a drifted A(H3N2) clade.

Respiratory Syncytial Virus-Associated Hospitalizations Among Young Children: 2015-2016

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of hospitalized acute respiratory illness (ARI) among young children. With RSV vaccines and immunoprophylaxis agents in clinical development, we sought to update estimates of US pediatric RSV hospitalization burden.

METHODS

Children <5 years old hospitalized for ARI were enrolled through active, prospective, population-based surveillance from November 1, 2015, to June 30, 2016, at 7 US pediatric hospital sites. Clinical information was obtained from parent interviews and medical records. Midturbinate nasal and throat flocked swabs were collected and tested for RSV by using molecular diagnostic assays at each site. We conducted descriptive analyses and calculated population-based rates of RSV-associated hospitalizations.

RESULTS

Among 2969 hospitalized children included in analyses, 1043 (35%) tested RSV-positive; 903 (87%) children who were RSV-positive were <2 years old, and 526 (50%) were <6 months old. RSV-associated hospitalization rates were 2.9 per 1000 children <5 years old and 14.7 per 1000 children <6 months old; the highest age-specific rate was observed in 1-month-old infants (25.1 per 1000). Most children who were infected with RSV (67%) had no underlying comorbid conditions and no history of preterm birth.

CONCLUSIONS

During the 2015-2016 season, RSV infection was associated with one-third of ARI hospitalizations in our study population of young children. Hospitalization rates were highest in infants <6 months. Most children who were RSV-positive had no history of prematurity or underlying medical conditions, suggesting that all young children could benefit from targeted interventions against RSV.

Severe Acute Respiratory Syndrome Coronavirus 2 Infections in Children: Multicenter Surveillance, United States, January-March 2020

Previous reports of coronavirus disease 2019 among children in the United States have been based on health jurisdiction reporting. We performed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing on children enrolled in active, prospective, multicenter surveillance during January-March 2020. Among 3187 children, only 4 (0.1%) SARS-CoV-2-positive cases were identified March 20-31 despite evidence of rising community circulation.

Detection of Clostridioides difficile by Real-time PCR in Young Children Does Not Predict Disease

OBJECTIVES

Diagnosing Clostridioides difficile infections in young children with high asymptomatic colonization is challenging. We compared the frequency of C difficile detection by polymerase chain reaction (PCR) in healthy control (HC) children with those with acute gastroenteritis (AGE) and evaluated fecal-lactoferrin and organism load as possible indicators of true C difficile infection disease.

METHODS

Stool was collected from children <2 years old with AGE and from HCs. C difficile was detected by real-time PCR, and lactoferrin was measured by enzyme-linked immunosorbent assay. Clinical data were obtained via interviews and chart review. Mann-Whitney U test and χ² tests were used for group comparisons.

RESULTS

Of 524 stools collected from 524 children (250 with AGE, 274 HCs), C difficile was detected less in children with AGE (14%, 36 of 250) than in HCs (28%, 76 of 274) stools (P < .0001). Among infants <1 year old (n = 297), C difficile was detected in 18% of children with AGE versus 32% of HCs (P < .005), and among children 1 to 2 years old (n = 227), C difficile was detected in 10% of children with AGE versus 21% of HCs (P < .02). There was no significant difference in C difficile PCR cycle threshold values between children with AGE and HCs or lactoferrin levels in C difficile PCR-positive versus -negative stools.

CONCLUSIONS

HC children <2 years of age had higher rates of C difficile detection by PCR than children with AGE; C difficile detection by real-time PCR alone is not a reliable means to diagnose C difficile disease in children <2 years old.

Validation of Acute Gastroenteritis-related International Classification of Diseases, Clinical Modification Codes in Pediatric and Adult US Populations

International Classification of Diseases diagnostic codes are used to estimate acute gastroenteritis (AGE) disease burden. We validated AGE-related codes in pediatric and adult populations using 2 multiregional active surveillance platforms. The sensitivity of AGE codes was similar (54% and 58%) in both populations and increased with addition of vomiting-specific codes.

No longer a historical ailment: two cases of childhood scurvy with recommendations for bone health providers

PURPOSE

Scurvy, due to vitamin C deficiency, is commonly referenced as a "forgotten" or "historical" disease. A growing number of case reports challenge this notion. Bone health providers are often consulted early in the presentation of scurvy to evaluate musculoskeletal complaints resulting from impaired collagen production and disrupted endochondral bone formation. In this report, we describe two cases of childhood scurvy. Our objective is to summarize the key features of scurvy for bone health providers, with the goal of raising awareness and facilitating diagnosis in future cases.

CASE DESCRIPTIONS

Case one occurred in a 12-year-old non-verbal, non-ambulatory female on a ketogenic diet for refractory epilepsy. Clinical findings included hemarthrosis, transfusion dependent anemia, elevated inflammatory markers, and epiphysiolysis. Magnetic resonance imaging (MRI) revealed multi-focal bone marrow signal abnormalities and physeal irregularities. Case two occurred in a typically developing 5-year-old male presenting with limp and knee pain. Symptoms progressed despite casting and immobilization. Mild anemia, elevated inflammatory markers, and multi-focal marrow and physeal MRI abnormalities were identified. Subsequent dietary history revealed total absence of fruit or vegetable consumption. The diagnosis of scurvy was confirmed in both cases by undetectable plasma vitamin C concentrations. Treatment with vitamin C led to rapid clinical improvement.

CONCLUSION

Scurvy can no longer be considered a historical diagnosis and should not be forgotten when evaluating children with musculoskeletal ailments. Early recognition of the signs, symptoms, and imaging findings of scurvy can reduce the clinical burden of this disease with the timely initiation of vitamin C therapy.

Evidence for Household Transmission of Rotavirus in the United States, 2011-2016

BACKGROUND

Rotavirus is a leading cause of acute gastroenteritis (AGE) in children and is highly transmissible. In this study, we assessed the presence of AGE in household contacts (HHCs) of pediatric patients with laboratory-confirmed rotavirus.

METHODS

Between December 2011 and June 2016, children aged 14 days to 11 years with AGE were enrolled at 1 of 7 hospitals or emergency departments as part of the New Vaccine Surveillance Network. Parental interviews, medical and vaccination records, and stool specimens were collected at enrollment. Stool was tested for rotavirus by an enzyme immunoassay and confirmed by real-time or conventional reverse transcription-polymerase chain reaction assay or repeated enzyme immunoassay. Follow-up telephone interviews were conducted to assess AGE in HHCs the week after the enrolled child's illness. A mixed-effects multivariate model was used to calculate odds ratios.

RESULTS

Overall, 829 rotavirus-positive subjects and 8858 rotavirus-negative subjects were enrolled. Households of rotavirus-positive subjects were more likely to report AGE illness in ≥1 HHC than were rotavirus-negative households (35% vs 20%, respectively; P < .0001). A total of 466 (16%) HHCs of rotavirus-positive subjects reported AGE illness. Of the 466 ill HHCs, 107 (23%) sought healthcare; 6 (6%) of these encounters resulted in hospitalization. HHCs who were <5 years old (odds ratio, 2.2 [P = .004]) were more likely to report AGE illness than those in other age groups. In addition, 144 households reported out-of-pocket expenses (median, $20; range, $2-$640) necessary to care for an ill HHC.

CONCLUSIONS

Rotavirus-associated AGE in children can lead to significant disease burden in HHCs, especially in children aged <5 years. Prevention of pediatric rotavirus illness, notably through vaccination, can prevent additional illnesses in HHCs.

Nontraditional Uses of Live Attenuated Influenza Vaccine: School-Located Influenza Vaccination

Immunization against influenza continues to be the best method of preventing influenza infection in children, and additionally, indirectly helping to lower disease in adults, given the role of children as "spreaders" of influenza to the community at large. An increasing evidence base exists for the use of school-located influenza vaccination (SLIV) programs to increase the influenza vaccination rates among children. Live, attenuated influenza vaccine (LAIV) has unique characteristics that make it useful for SLIV programs, including ease of immunization without needles, faster delivery, and in many (but not all) years, good vaccine effectiveness. Reviewed herein are results of selected published trials as well as guidance on planning a successful SLIV program.

Viral Etiology of Acute Gastroenteritis in <2-Year-Old US Children in the Post-Rotavirus Vaccine Era

BACKGROUND

The rotavirus disease burden has declined substantially since rotavirus vaccine was introduced in the United States in 2006. The aim of this study was to determine the viral etiology of acute gastroenteritis (AGE) in US children aged <2 years.

METHODS

The New Vaccine Surveillance Network (NVSN) of geographically diverse US sites conducts active pediatric population-based surveillance in hospitals and emergency departments. Stool samples were collected from children aged <2 years with symptoms of AGE (n = 330) and age-matched healthy controls (HCs) (n = 272) between January and December 2012. Samples were tested by real-time reverse-transcriptase polymerase chain reaction assays {adenovirus (type 40 and 41), norovirus, parechovirus A, enterovirus, sapovirus, and astrovirus} and an enzyme immunoassay (rotavirus). All samples that tested positive were genotyped.

RESULTS

Detection rates of pathogens in children with AGE versus those of HCs were, respectively, 23.0% versus 6.6% for norovirus (P < .01), 23.0% versus 16.0% for adenovirus (P = .08), 11.0% versus 16.0% for parechovirus A (P = .09), 11.0% versus 9.0% for enterovirus (P = .34), 7.0% versus 3.0% for sapovirus (P = .07), 3.0% versus 0.3% for astrovirus (P = .01), and 3.0% versus 0.4% for rotavirus (P = .01). A high prevalence of adenovirus was detected at 1 surveillance site (49.0% for children with AGE and 43.0% for HCs). Norovirus GII.4 New Orleans was the most frequently detected (33.0%) norovirus genotype. Codetection of >1 virus was more common in children with AGE (16.0%) than in HCs (10.0%) (P = .03).

CONCLUSIONS

Norovirus, astrovirus, sapovirus, and rotavirus were detected significantly more in children with AGE than in HCs, and norovirus was the leading AGE-causing pathogen in US children aged <2 years during the year 2012.