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COVID-19 vaccinations are now recommended in the United States (U.S.) for children ≥ 6 months old. However, pediatric vaccination rates remain low, particularly in the Hispanic/Latinx population.Using the 4C vaccine hesitancy framework (calculation, complacency, confidence, convenience), we examined parental attitudes in the emergency department (ED) towards COVID-19 vaccination, identified dimensions of parental vaccine hesitancy, and assessed parental willingness to have their child receive the COVID-19 vaccine.As part of a larger multi-methods study examining influenza vaccine hesitancy, we conducted interviews that included questions about COVID-19 vaccine authorization for children. We used directed content analysis to extract qualitative themes from 3 groups of parents in the ED: Hispanic/Latinx Spanish speaking (HS), Hispanic/Latinx English speaking (HE), non-Hispanic/non-Latinx White English speaking (WE). Themes were triangulated with the Parent Attitudes about Childhood Vaccines (PACV) survey, where higher scores indicate increased vaccine hesitancy.Factors influencing vaccine hesitancy were mapped to the 4C framework from 58 sets of interviews and PACVs. HE and HS parents, compared to WE parents, had less knowledge about COVID-19 and its vaccine, and more beliefs in COVID-19 vaccine myths. However, both HS and HE parent groups were more inclined to endorse COVID-19 vaccine effectiveness as a reason to have their children vaccinated. HS parents felt that COVID-19 increased their fear of illnesses in general and were worried about confusing COVID-19 with other infections. Median PACV scores of HS (Mdn = 20) and HE (Mdn = 20) parent groups were higher than of WE parents (Mdn = 10), but parental willingness to have their child receive COVID-19 vaccination was similar across groups.Higher COVID-19 vaccine hesitancy among HS and HE parents compared to WE parents may be attributed to insufficient knowledge about COVID-19, its vaccine, along with COVID-19 vaccine myths. Efforts to provide targeted vaccine education to different populations is warranted.

Infants younger than 6 months of age are at high risk for complications of coronavirus disease 2019 (Covid-19) and are not eligible for vaccination. Transplacental transfer of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after maternal Covid-19 vaccination may confer protection against Covid-19 in infants.We used a case-control test-negative design to assess the effectiveness of maternal vaccination during pregnancy against hospitalization for Covid-19 among infants younger than 6 months of age. Between July 1, 2021, and March 8, 2022, we enrolled infants hospitalized for Covid-19 (case infants) and infants hospitalized without Covid-19 (control infants) at 30 hospitals in 22 states. We estimated vaccine effectiveness by comparing the odds of full maternal vaccination (two doses of mRNA vaccine) among case infants and control infants during circulation of the B.1.617.2 (delta) variant (July 1, 2021, to December 18, 2021) and the B.1.1.259 (omicron) variant (December 19, 2021, to March 8, 2022).A total of 537 case infants (181 of whom had been admitted to a hospital during the delta period and 356 during the omicron period; median age, 2 months) and 512 control infants were enrolled and included in the analyses; 16% of the case infants and 29% of the control infants had been born to mothers who had been fully vaccinated against Covid-19 during pregnancy. Among the case infants, 113 (21%) received intensive care (64 [12%] received mechanical ventilation or vasoactive infusions). Two case infants died from Covid-19; neither infant's mother had been vaccinated during pregnancy. The effectiveness of maternal vaccination against hospitalization for Covid-19 among infants was 52% (95% confidence interval [CI], 33 to 65) overall, 80% (95% CI, 60 to 90) during the delta period, and 38% (95% CI, 8 to 58) during the omicron period. Effectiveness was 69% (95% CI, 50 to 80) when maternal vaccination occurred after 20 weeks of pregnancy and 38% (95% CI, 3 to 60) during the first 20 weeks of pregnancy.Maternal vaccination with two doses of mRNA vaccine was associated with a reduced risk of hospitalization for Covid-19, including for critical illness, among infants younger than 6 months of age. (Funded by the Centers for Disease Control and Prevention.).

Spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant, which led to increased U.S. hospitalizations for coronavirus disease 2019 (Covid-19), generated concern about immune evasion and the duration of protection from vaccines in children and adolescents.Using a case-control, test-negative design, we assessed vaccine effectiveness against laboratory-confirmed Covid-19 leading to hospitalization and against critical Covid-19 (i.e., leading to receipt of life support or to death). From July 1, 2021, to February 17, 2022, we enrolled case patients with Covid-19 and controls without Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2 messenger RNA vaccine) at least 14 days before illness among case patients and controls, according to time since vaccination for patients 12 to 18 years of age and in periods coinciding with circulation of B.1.617.2 (delta) (July 1, 2021, to December 18, 2021) and omicron (December 19, 2021, to February 17, 2022) among patients 5 to 11 and 12 to 18 years of age.We enrolled 1185 case patients (1043 [88%] of whom were unvaccinated, 291 [25%] of whom received life support, and 14 of whom died) and 1627 controls. During the delta-predominant period, vaccine effectiveness against hospitalization for Covid-19 among adolescents 12 to 18 years of age was 93% (95% confidence interval [CI], 89 to 95) 2 to 22 weeks after vaccination and was 92% (95% CI, 80 to 97) at 23 to 44 weeks. Among adolescents 12 to 18 years of age (median interval since vaccination, 162 days) during the omicron-predominant period, vaccine effectiveness was 40% (95% CI, 9 to 60) against hospitalization for Covid-19, 79% (95% CI, 51 to 91) against critical Covid-19, and 20% (95% CI, -25 to 49) against noncritical Covid-19. During the omicron period, vaccine effectiveness against hospitalization among children 5 to 11 years of age was 68% (95% CI, 42 to 82; median interval since vaccination, 34 days).BNT162b2 vaccination reduced the risk of omicron-associated hospitalization by two thirds among children 5 to 11 years of age. Although two doses provided lower protection against omicron-associated hospitalization than against delta-associated hospitalization among adolescents 12 to 18 years of age, vaccination prevented critical illness caused by either variant. (Funded by the Centers for Disease Control and Prevention.).

The increasing incidence of pediatric hospitalizations associated with coronavirus disease 2019 (Covid-19) caused by the B.1.617.2 (delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United States has offered an opportunity to assess the real-world effectiveness of the BNT162b2 messenger RNA vaccine in adolescents between 12 and 18 years of age.We used a case-control, test-negative design to assess vaccine effectiveness against Covid-19 resulting in hospitalization, admission to an intensive care unit (ICU), the use of life-supporting interventions (mechanical ventilation, vasopressors, and extracorporeal membrane oxygenation), or death. Between July 1 and October 25, 2021, we screened admission logs for eligible case patients with laboratory-confirmed Covid-19 at 31 hospitals in 23 states. We estimated vaccine effectiveness by comparing the odds of antecedent full vaccination (two doses of BNT162b2) in case patients as compared with two hospital-based control groups: patients who had Covid-19-like symptoms but negative results on testing for SARS-CoV-2 (test-negative) and patients who did not have Covid-19-like symptoms (syndrome-negative).A total of 445 case patients and 777 controls were enrolled. Overall, 17 case patients (4%) and 282 controls (36%) had been fully vaccinated. Of the case patients, 180 (40%) were admitted to the ICU, and 127 (29%) required life support; only 2 patients in the ICU had been fully vaccinated. The overall effectiveness of the BNT162b2 vaccine against hospitalization for Covid-19 was 94% (95% confidence interval [CI], 90 to 96); the effectiveness was 95% (95% CI, 91 to 97) among test-negative controls and 94% (95% CI, 89 to 96) among syndrome-negative controls. The effectiveness was 98% against ICU admission and 98% against Covid-19 resulting in the receipt of life support. All 7 deaths occurred in patients who were unvaccinated.Among hospitalized adolescent patients, two doses of the BNT162b2 vaccine were highly effective against Covid-19-related hospitalization and ICU admission or the receipt of life support. (Funded by the Centers for Disease Control and Prevention.).

COVID-19 vaccination is recommended for persons who are pregnant, breastfeeding, trying to get pregnant now, or who might become pregnant in the future, to protect them from COVID-19.

BACKGROUND Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–specific antibodies have been detected in human milk up to 6 weeks post–coronavirus disease 2019 (COVID-19) vaccination. We evaluated SARS-CoV-2-specific antibodies, neutralization activity, effect of pasteurization, and persistence through 6 months after vaccination. METHODS This prospective longitudinal study enrolled 30 pregnant or lactating women. SARS-CoV-2 antibodies and neutralization capacity were analyzed using an enzyme-linked immunosorbent assay compared at prevaccination and 1, 3, and 6 months postvaccination, and through Holder pasteurization. RESULTS Human milk SARS-CoV-2-specific IgG levels peaked at 1 month postvaccination and persisted above prevaccination levels for at least 6 months (P = .005). SARS-CoV-2-specific IgA was detected at 1 and 3 months (both P < .001) but waned by 6 months compared with baseline (P = .07). Milk SARS-CoV-2-specific IgG and IgA correlated with serum IgG at the same time point (R2 = 0.37, P < .001 and R2 = 0.19, P < .001). Neutralization activity was seen in 83.3%, 70.4%, and 25.0% of milk samples at 1, 3, and 6 months postvaccination. Neutralization most strongly correlated with SARS-CoV-2-specific IgG (R2 = 0.57, P < .001). Pre- and postpasteurization samples showed similar IgG (0.84 vs 1.07, P = .36) and neutralizing activity (57.7% vs 58.7% inhibition, P = .27), but lower IgM and IgA levels postpasteurization (0.09 vs 0.06, P = .004 and 0.21 vs 0.18, P = .043). CONCLUSIONS The data suggest that human milk SARS-CoV-2-specific antibodies may be available to milk-fed infants for up to 6 months. In addition, donor milk from vaccinated mothers retain IgG and neutralizing activity.

Introduction: The balance of risks and benefits of COVID-19 vaccination in children is more complex than in adults with limited paediatric data resulting in no global consensus on whether all healthy children should be vaccinated. We sought to assess the safety, efficacy, and effectiveness of childhood vaccination against SARS-CoV-2, as well as better understanding perceptions of vaccination in parents and vaccine experts. Methods: We performed a literature review for COVID-19 vaccine safety, efficacy, effectiveness, and perceptions. We searched international safety databases for safety data and developed an electronic survey to elicit country-specific COVID-19 immunisation data, including vaccine regulations, policies, rates, and public attitudes solicited from vaccine experts. Results: Nine studies were included in the final safety analysis. Local reactions were frequently reported across all studies and vaccine types. Adverse events reported to surveillance systems tended to be non-serious, and commonly included injection site reactions and dizziness. Twenty-three studies reported immunogenicity, efficacy, and effectiveness data. There were nine randomised control trials of six different vaccine types, which showed seroconversion of neutralising antibodies in vaccinated children ranging from 88% to 100%. The vaccine efficacy for Pfizer and Moderna vaccines ranged from 88% to 100%. There were 118 survey responses representing 55 different countries. Reported vaccination rates ranged from

Background Risk factors for MIS-C, a rare but serious hyperinflammatory syndrome associated with SARS-CoV-2 infection, remain unclear. We evaluated household, clinical, and environmental risk factors potentially associated with MIS-C. Methods This investigation included MIS-C cases hospitalized in 14 US pediatric hospitals in 2021. Outpatient controls were frequency-matched to case-patients by age group and site and had a positive SARS-CoV-2 viral test within 3 months of the admission of their matched MIS-C case (Figure 1). We conducted telephone surveys with caregivers and evaluated potential risk factors using mixed effects multivariable logistic regression, including site as a random effect. We queried regarding exposures within the month before hospitalization for MIS-C cases or the month after a positive COVID-19 test for controls. Figure.Patient enrollment timeline. Enrollment scheme for MIS-C case-patients and SARS-CoV-2-positive outpatient controls. MIS-C case-patients were identified through hospital electronic medical records, while two outpatient controls per case were identified through registries of outpatient SARS-CoV-2 testing logs at facilities affiliated with that medical center. Caregivers of outpatient controls were interviewed at least four weeks after their positive test to ensure they did not develop MIS-C after their infection. Results We compared 275 MIS-C case-patients with 494 outpatient SARS-CoV-2-positive controls. Race, ethnicity and social vulnerability indices were similar. MIS-C was more likely among persons who resided in households with >1 resident per room (aOR=1.6, 95% CI: 1.1–2.2), attended a large (≥10 people) event with little to no mask-wearing (aOR=2.2, 95% CI: 1.4–3.5), used public transportation (aOR=1.6, 95% CI: 1.2–2.1), attended school >2 days per week with little to no mask wearing (aOR=2.1, 95% CI: 1.0–4.4), or had a household member test positive for COVID-19 (aOR=2.1, 95% CI: 1.3–3.3). MIS-C was less likely among children with comorbidities (aOR=0.5, 95% CI: 0.3–0.9) and in those who had >1 positive SARS-CoV-2 test at least 1 month apart (aOR=0.4, 95% CI: 0.2–0.6). MIS-C was not associated with a medical history of recurrent infections or family history of underlying rheumatologic disease. Conclusion Household crowding, limited masking at large indoor events or schools and use of public transportation were associated with increased likelihood of developing MIS-C after SARS-CoV-2 infection. In contrast, decreased likelihood of MIS-C was associated with having >1 SARS-CoV-2 positive test separated by at least a month. Our data suggest that additional studies are needed to determine if viral load, and/or recurrent infections in the month prior to MIS-C contribute to MIS-C risk. Medical and family history were not associated with MIS-C in our analysis. Disclosures Natasha B. Halasa, MD, Quidel: Grant/Research Support|Quidel: equipment donation|Sanofi: Grant/Research Support|Sanofi: HAI testing and vaccine donation Mark Hall, MD, Abbvie: Service on a Data Safety Monitoring Board|Kiadis: Licensing income unrelated to the current submission 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 Pia S. Pannaraj, MD, MPH, AstraZeneca: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi-Pasteur: Advisor/Consultant|Seqirus: Advisor/Consultant Charlotte V. Hobbs, MD, Biofire (Biomerieux): Advisor/Consultant.

Background Age and obesity status are associated with severe outcomes among hospitalized individuals with COVID‐19. It remains unclear whether age and obesity are risk factors for milder COVID‐19 illness. Methods We prospectively enrolled SARS‐CoV‐2‐exposed individuals. Participants recorded symptoms for 28 days and were tested for SARS‐CoV‐2 by reverse transcription polymerase chain reaction (RT‐PCR) and serology. Type, number, and duration of symptoms and SARS‐CoV‐2 laboratory parameters were compared by age and obesity status. Results Of 552 individuals enrolled from June 2020 to January 2021, 470 (85.1%) tested positive for SARS‐CoV‐2 including 261 (55.5%) adults ≥18 years, 61 (13.0%) adolescents 12–17 years, and 148 (31.5%) children

Measures to limit SARS-CoV-2 transmission in 2020 reduced other viral infections. Among 7 US children’s hospitals, invasive pneumococcal disease cumulative incidence decreased by 46% in 2020 vs 2017-2019. Limited droplet transmission of pneumococci and preceding viral pathogens may be responsible.

Background Pfizer-BioNTech COVID-19 vaccine received emergency use authorization for persons ≥ 16 years in December 2020 and for adolescents 12–15 years in May 2021. Despite the clear benefits and favorable safety profile, vaccine uptake in adolescents has been suboptimal. We sought to assess factors associated with COVID-19 non-vaccination in adolescents 12–18 years of age. Methods Between June 1, 2021 and April 29, 2022, we assessed factors associated with COVID-19 non-vaccination in hospitalized adolescents ages 12–18 years enrolled in the Overcoming COVID-19 vaccine effectiveness network. Demographic characteristics and clinical information were captured through parent interviews and/or electronic medical record abstraction; COVID-19 vaccination was assessed through documented sources. We assessed associations between receipt of the COVID-19 vaccine and demographic and clinical factors using univariate and multivariable logistic regression and estimated adjusted odds ratios (aOR) for each factor associated with non-vaccination. Results Among 1665 hospitalized adolescents without COVID-19, 56% were unvaccinated. Unvaccinated adolescents were younger (median age 15.1 years vs. 15.4 years, p Conclusions Efforts to increase COVID-19 vaccination of adolescents should focus on persons with geographic, socioeconomic, and medical risk factors associated with non-vaccination.

Multisystem inflammatory syndrome in children (MIS-C), linked to antecedent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is associated with considerable morbidity. Prevention of SARS-CoV-2 infection or coronavirus disease 2019 (COVID-19) by vaccination might also decrease MIS-C likelihood.In a multicenter case-control public health investigation of children ages 5-18 years hospitalized from July 1, 2021 to April 7, 2022, we compared the odds of being fully vaccinated (two doses of BNT162b2 vaccine ≥28 days before hospital admission) between MIS-C case-patients and hospital-based controls who tested negative for SARS-CoV-2. These associations were examined by age group, timing of vaccination, and periods of Delta and Omicron variant predominance using multivariable logistic regression.We compared 304 MIS-C case-patients (280 [92%] unvaccinated) with 502 controls (346 [69%] unvaccinated). MIS-C was associated with decreased likelihood of vaccination (aOR, 0.16 95% CI, 0.10-0.26), including among children ages 5-11 years (aOR, 0.22 95% CI, 0.10-0.52), ages 12-18 years (aOR, 0.10 95% CI, 0.05-0.19), and during the Delta (aOR, 0.06 95% CI, 0.02-0.15) and Omicron (aOR, 0.22 95% CI, 0.11-0.42) variant-predominant periods. This association persisted beyond 120 days after the second dose (aOR, 0.08, 95% CI, 0.03-0.22) in 12-18 year-olds. Among all MIS-C case-patients, 187 (62%) required intensive care unit admission and 280 (92%) vaccine-eligible patients were unvaccinated.Vaccination with two doses of BNT162b2 is associated with reduced likelihood of MIS-C in children ages 5-18 years. Most vaccine eligible hospitalized patients with MIS-C were unvaccinated.

Pediatric oncology patients are at risk for poor outcomes with respiratory viral infections. Outcome data for COVID-19 in children and young adults with cancer are needed; data are sparse for obese/overweight and adolescent and young adult subgroups. We conducted a single center cohort study of COVID-19 outcomes in patients younger than 25 years with cancer. Candidate hospitalization risk factors were analyzed via univariable and multivariable analyses. Eighty-seven patients with cancer and COVID-19 were identified. Most were Hispanic/Latinx (n = 63, 72%). Forty-two (48%) were overweight/obese. Anticancer therapy included chemotherapy only (n = 64, 74%), chimeric antigen receptor T-cells (CAR-T, n = 7), hematopoietic stem cell transplantation (HSCT, n = 12), or CAR-T and HSCT (n = 4). There was no COVID-19 related mortality. Twenty-six patients (30%) required COVID-19 related hospitalization; 4 required multiple hospitalizations. Nine (10%) had severe/critical infection; 6 needed intensive care. COVID-19 resulted in anticancer therapy delays in 22 (34%) of 64 patients on active therapy (median delay = 14 days). Factors associated with hospitalization included steroids within 2 weeks prior to infection, lymphopenia, previous significant non-COVID infection, and low COVID-19 PCR cycle threshold value. CAR-T recipients with B-cell aplasia tended to have severe/critical infection (3 of 7 patients). A COVID-19 antibody response was detected in 14 of 32 patients (44%). A substantial proportion of COVID-19 infected children and young adults with cancer require inpatient management; morbidity may be high in B-cell immunodeficiency. However, a majority of patients can be taken through chemotherapy without prolonged therapy delays. Viral load is a potential outcome predictor in COVID-19 in pediatric cancer.

Breastfeeding protects against mucosal infections in infants. The underlying mechanisms through which immunity develops in human milk following maternal infection with mucosal pathogens are not well understood. We simulated nasal mucosal influenza infection through live attenuated influenza vaccination (LAIV) and compared immune responses in milk to inactivated influenza vaccination (IIV). Transcriptomic analysis was performed on RNA extracted from human milk cells to evaluate differentially expressed genes and pathways on days 1 and 7 post-vaccination. Both LAIV and IIV vaccines induced influenza-specific IgA that persisted for at least 6 months. Regulation of type I interferon production, toll-like receptor, and pattern recognition receptor signaling pathways were highly upregulated in milk on day 1 following LAIV but not IIV at any time point. Upregulation of innate immunity in human milk may provide timely protection against mucosal infections until antigen-specific immunity develops in the human milk-fed infant.

Objective:To investigate the effects of environmental cleaning and the installation of heat and moisture exchangers (HMEs) to reduce neonatal carbapenem-resistant Acinetobacter baumannii (CRAB) sepsis and colonization as well as antimicrobial use.Design:We conducted a 7-year, quasi-experimental study.Setting and patients:All neonates admitted to a neonatal intensive care unit (NICU).Methods:We compared the trends for CRAB sepsis and colonization before (period 1, 2011–2013) and after (period 3, 2015–2017) a 12-month intervention period in 2014 (period 2) to incorporate a combination of HME use and sodium hypochlorite cleaning (5,000 ppm in the NICU and 500 ppm in the neonatal environment) using interrupted time series analysis with segmented regression.Results:During the 7-year study period, 3,367 neonates were admitted to the NICU; the prevalence rates of CRAB sepsis and endotracheal CRAB colonization were 0.5 per 1,000 patient days, and 19.4 per 1,000 ventilator days. A comparison of period 1 to period 3 showed significant decreases in the percentages of both CRAB of A. baumannii sepsis (100% versus 11%) and endotracheal colonization (76% vs 52%) following the introduction of disposable HMEs and sodium hypochlorite cleaning (both P < .001). In period 3, compared with period 1, segmented regression analysis showed significant reductions in endotracheal CRAB colonization per 1,000 ventilator days (ie, change in level) and both carbapenem and colistin use (changes in both level and slope) (P < .001).Conclusions:Interventions featuring environmental cleaning and use of HMEs led to a sustainable reduction of CRAB colonization coupled with a reduction in broad-spectrum antimicrobial use in the NICU.

Breastfeeding protects against mucosal infections in infants. The underlying mechanisms through which immunity develops in human milk following maternal infection with mucosal pathogens are not well understood. We simulated nasal mucosal influenza infection through live attenuated influenza vaccination (LAIV) and compared immune responses in milk to inactivated influenza vaccination (IIV). Transcriptomic analysis was performed on RNA extracted from human milk cells to evaluate differentially expressed genes and pathways on days 1 and 7 post-vaccination. Both LAIV and IIV vaccines induced influenza-specific IgA that persisted for at least 6 months. Regulation of type I interferon production, toll-like receptor, and pattern recognition receptor signaling pathways were highly upregulated in milk on day 1 following LAIV but not IIV at any time point. Upregulation of innate immunity in human milk may provide timely protection against mucosal infections until antigen-specific immunity develops in the human milk-fed infant.

Multisystem inflammatory syndrome in children (MIS-C) is a severe postinfectious hyperinflammatory condition, which generally occurs 2-6 weeks after a typically mild or asymptomatic infection with SARS-CoV-2, the virus that causes COVID-19 (1-3). In the United States, the BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine is currently authorized for use in children and adolescents aged 5-15 years under an Emergency Use Authorization and is fully licensed by the Food and Drug Administration for persons aged ≥16 years (4). Prelicensure randomized trials in persons aged ≥5 years documented high vaccine efficacy and immunogenicity (5)

Pfizer-BioNTech COVID-19 vaccine is authorized for use in children and adolescents aged 12-15 years and is licensed by the Food and Drug Administration (FDA) for persons aged ≥16 (1). A randomized placebo-controlled trial demonstrated an efficacy of 100% (95% confidence interval [CI] = 75.3%-100%) in preventing outpatient COVID-19 in persons aged 12-15 years (2); however, data among adolescents on vaccine effectiveness (VE) against COVID-19 in real-world settings are limited, especially among hospitalized patients. In early September 2021, U.S. pediatric COVID-19 hospitalizations reached the highest level during the pandemic (3,4). In a test-negative, case-control study at 19 pediatric hospitals in 16 states during June 1-September 30, 2021, the effectiveness of 2 doses of Pfizer-BioNTech vaccine against COVID-19 hospitalization was assessed among children and adolescents aged 12-18 years. Among 464 hospitalized persons aged 12-18 years (179 case-patients and 285 controls), the median age was 15 years, 72% had at least one underlying condition, including obesity, and 68% attended in-person school. Effectiveness of 2 doses of Pfizer-BioNTech vaccine against COVID-19 hospitalization was 93% (95% CI = 83%-97%), during the period when B.1.617.2 (Delta) was the predominant variant. This evaluation demonstrated that 2 doses of Pfizer-BioNTech vaccine are highly effective at preventing COVID-19 hospitalization among persons aged 12-18 years and reinforces the importance of vaccination to protect U.S. youths against severe COVID-19.

This study investigates the timeframe that optimizes saliva sensitivity for SARS-CoV-2 detection using reverse transcriptase–polymerase chain reaction (RT-PCR) testing.

This study assessed the impact of respiratory syncytial virus-confirmed hospitalizations (RSVH) on caregivers of high-risk preterm infants. Caregivers for infants born at 29 to 35 weeks' gestational age and hospitalized for confirmed RSV disease responded to measures of self-rated and perceived infant stress (1-7; 7 = very stressful), perceived infant health (0-100; 100 = best imaginable health), and productivity impairment. Data were collected at hospital discharge through 1 month post-discharge. Caregiver responses indicated high stress levels, poor health, and productivity loss were reported at discharge; however, steady improvements were seen through 1 month post-discharge: caregiver-rated stress (from 6 to 2), infant stress (5 to 1), caregiver-perceived infant health (64 to 84), and productivity loss (mothers: 91% to 31%; fathers: 81% to 18%). Qualitative results indicated emotional impact, family routine disruption, financial concerns, and medical concerns persisted at 1 month post-discharge. This study found the caregiver burden of RSVH persists at least 1 month beyond discharge.

Objective The SENTINEL1 observational study characterized confirmed respiratory syncytial virus hospitalizations (RSVH) among U.S. preterm infants born at 29 to 35 weeks' gestational age (wGA) not receiving respiratory syncytial virus (RSV) immunoprophylaxis (IP) during the 2014 to 2015 and 2015 to 2016 RSV seasons. Study Design All laboratory-confirmed RSVH at participating sites during the 2014 to 2015 and 2015 to 2016 RSV seasons (October 1–April 30) lasting ≥24 hours among preterm infants 29 to 35 wGA and aged Results Results were similar across the two seasons. Among infants with community-acquired RSVH (N = 1,378), 45% were admitted to the intensive care unit (ICU) and 19% required invasive mechanical ventilation (IMV). There were two deaths. Infants aged Conclusion Among U.S. preterm infants 29 to 35 wGA not receiving RSV IP, RSVH are often severe with almost one-half requiring ICU admission and about one in five needing IMV.

As establishment of SARS-CoV-2-specific T cell memory in children remains largely unexplored, we recruited convalescent COVID-19 children and adults to define their circulating memory SARS-CoV-2-specific CD4+ and CD8+ T cells prior to vaccination. We analysed epitope-specific T cells directly ex vivo using seven HLA class-I and class-II tetramers presenting SARS-CoV-2 epitopes, together with Spike-specific B cells. Unvaccinated children who seroconverted had comparable spike-specific, but lower ORF1a- and N-specific memory T cell responses compared to adults. This agreed with our TCR sequencing data showing reduced clonal expansion in children. A strong stem cell memory phenotype and common T cell receptor motifs were detected within tetramer-specific T cells in seroconverted children. Conversely, children who did not seroconvert had tetramer-specific T cells of predominantly naïve phenotypes and diverse TCRαβ repertoires. Our study demonstrates generation of SARS-CoV-2-specific T cell memory with common TCRαβ motifs in unvaccinated seroconverted children after their first virus encounter.

SummaryBackgroundThere is increasing concern that persistent infection of SARS-CoV-2 within immunocompromised hosts could serve as a reservoir for mutation accumulation and subsequent emergence of novel strains with the potential to evade immune responses.MethodsWe describe three patients with acute lymphoblastic leukemia who were persistently positive for SARS-CoV-2 by real-time polymerase chain reaction. Viral viability from longitudinally-collected specimens was assessed. Whole-genome sequencing and serological studies were performed to measure viral evolution and evidence of immune escape.FindingsWe found compelling evidence of ongoing replication and infectivity for up to 162 days from initial positive by subgenomic RNA, single-stranded RNA, and viral culture analysis. Our results reveal a broad spectrum of infectivity, host immune responses, and accumulation of mutations, some with the potential for immune escape.InterpretationOur results highlight the need to reassess infection control precautions in the management and care of immunocompromised patients. Routine surveillance of mutations and evaluation of their potential impact on viral transmission and immune escape should be considered.FundingThe work was partially funded by The Saban Research Institute at Children’s Hospital Los Angeles intramural support for COVID-19 Directed Research (X.G. and J.D.B.), the Johns Hopkins Center of Excellence in Influenza Research and Surveillance HHSN272201400007C (A.P.), NIH/NIAID R01AI127877 (S.D.B.), NIH/NIAID R01AI130398 (S.D.B.), NIH 1U54CA260517 (S.D.B.), an endowment to S.D.B. from the Crown Family Foundation, an Early Postdoc.Mobility Fellowship Stipend to O.F.W. from the Swiss National Science Foundation (SNSF), and a Coulter COVID-19 Rapid Response Award to S.D.B. L.G. is a SHARE Research Fellow in Pediatric Hematology-Oncology.

Pollution of the environment is increasing and threatens the health and wellbeing of adults and children around the globe. The impact of air pollution on pulmonary and cardiovascular disease has been well documented, but it also has a deleterious effect on reproductive health. Ulaanbaatar, the capital city of Mongolia, has one of the highest levels of air pollution in the world. During the extreme winters when temperatures routinely fall below −20 °C the level of air pollution can reach 80 times the WHO recommended safe levels. Heating mainly comes from coal, which is burned both in power stations, and in stoves in the traditional Ger housing. We studied the impact of air pollution on conception rates and birth outcomes in Ulaanbaatar using a retrospective analysis of health data collected from the Urguu Maternity hospital in Ulaanbaatar, Mongolia. Daily levels of SO2, NO2, PM10, and PM2.5 were collected from the government Air Quality Monitoring Stations in Ulaanbaatar for the same period as the study. In January, the month of highest pollution, there is a 3.2-fold decrease in conceptions that lead to the successfully delivered infants compared to October. The seasonal variations in conceptions resulting in live births in this study in Ulaanbaatar are shown to be 2.03 ± 0.20 (10-sigma) times greater than those in the Denmark/North America study of Wesselink et al., 2020. The two obvious differences between Ulaanbaatar and Europe/North America are pollution and temperature both of which are extreme in Ulaanbaatar. The extreme low temperature is mitigated by burning coal, which is the main source of domestic heat especially in the ger districts. This drives the level of pollution so the two are inextricably linked. Infants conceived in the months of June-October had the greatest cumulative PM2.5 pollution exposure over total gestation, yet these were also the pregnancies with the lowest PM2.5 exposure for the month of conception and three months prior to conception. The delivered-infant conception rate shows a markedly negative association with exposure to PM2.5 prior to and during the first month of pregnancy. This overall reduction in fecundity of the population of Ulaanbaatar is therefore a preventable health risk. It is of great consequence that the air pollution in Ulaanbaatar affects health over an entire lifespan including reproductive health. This could be remedied with a clean source of heating.

Testing efforts for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been burdened by the scarcity of testing materials and personal protective equipment for health care workers. The simple and painless process of saliva collection allows for widespread testing, but enthusiasm is hampered by variable performance compared to that of nasopharyngeal swab (NPS) samples., Testing efforts for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been burdened by the scarcity of testing materials and personal protective equipment for health care workers. The simple and painless process of saliva collection allows for widespread testing, but enthusiasm is hampered by variable performance compared to that of nasopharyngeal swab (NPS) samples. We prospectively collected paired NPS and saliva samples from a total of 300 unique adult and pediatric patients. SARS-CoV-2 RNA was detected in 32.2% (97/300) of the individuals using the TaqPath COVID-19 Combo kit (Thermo Fisher). Performance of saliva and NPS was compared against the total number of positives regardless of specimen type. The overall concordances for saliva and NPS were 91.0% (273/300) and 94.7% (284/300), respectively. The values for positive percent agreement (PPA) for saliva and NPS were 81.4% (79/97) and 89.7% (87/97), respectively. Saliva yielded detection of 10 positive cases that were negative by NPS. For symptomatic and asymptomatic pediatric patients not previously diagnosed with COVID-19, the performances of saliva and NPS were comparable (PPA, 82.4% versus 85.3%). The overall values for PPA for adults were 83.3% and 90.7% for saliva and NPS, respectively, with saliva yielding detection of 4 fewer cases than NPS. However, saliva performance for symptomatic adults was identical to NPS performance (PPA of 93.8%). With lower cost and self-collection capabilities, saliva can be an appropriate sample choice alternative to NPS for detection of SARS-CoV-2 in children and adults.

Background Chagas disease is a pathogenic parasitic infection with approximately 8 million cases worldwide and greater than 300,000 cases in the United States (U.S.). Chagas disease can lead to chronic cardiomyopathy and cardiac complications, with variable cardiac presentations in pediatrics making it difficult to recognize. The purpose of our study is to better understand current knowledge and experience with Chagas related heart disease among pediatric cardiologists in the U.S. Methods We prospectively disseminated a 19-question survey to pediatric cardiologists via 3 pediatric cardiology listservs. The survey included questions about demographics, Chagas disease presentation and experience. Results Of 139 responses, 119 cardiologists treat pediatric patients in the U.S. and were included. Most providers (87%) had not seen a case of Chagas disease in their practice; however, 72% also had never tested for it. The majority of knowledge-based questions about Chagas disease cardiac presentations were answered incorrectly, and 85% of providers expressed discomfort with recognizing cardiac presentations in children. Most respondents selected that they would not include Chagas disease on their differential diagnosis for presentations such as conduction anomalies, myocarditis and/or apical aneurysms, but would be more likely to include it if found in a Latin American immigrant. Of respondents, 87% agreed that they would be likely to attend a Chagas disease-related lecture. Conclusions Pediatric cardiologists in the U.S. have seen very few cases of Chagas disease, albeit most have not sent testing or included it in their differential diagnosis. Most individuals agreed that education on Chagas disease would be worth-while.

IntroductionThe progression and severity of the coronavirus disease 2019 (COVID-19), an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), varies significantly in the population. While the hallmarks of SARS-CoV-2 and severe COVID-19 within routine laboratory parameters are emerging, little is known about the impact of sex and age on these profiles.MethodsWe performed multidimensional analysis of millions of records of laboratory parameters and diagnostic tests for 178,887 individuals, of which 33,266 tested positive for SARS-CoV-2. These included complete blood cell count, electrolytes, metabolites, arterial blood gases, enzymes, hormones, cancer biomarkers, and others.ResultsCOVID-19 induced similar alterations in the laboratory parameters in males compared to females. Biomarkers of inflammation, such as C-reactive protein (CRP) and ferritin, were increased especially in older men with COVID-19, whereas other markers such as abnormal liver function tests were common across several age groups, except for young women. Low peripheral blood basophils and eosinophils were also more common in the elderly with COVID-19. Both male and female COVID-19 patients admitted to the intensive care unit (ICU) displayed alterations in the coagulation system, and higher levels of neutrophils, CRP, lactate dehydrogenase (LDH), among others.DiscussionOur study uncovers the laboratory profile of a large cohort of COVID-19 patients that underly discrepancies influenced by aging and biological sex. These profiles directly link COVID-19 disease presentation to an intricate interplay between sex, age and the immune response.One Sentence SummaryBig Data analysis of laboratory results from a large number of COVID-19 patients and controls reveals distinct disease profiles influenced by age and sex which may underly occurrence of severe disease.Key messages- What is the key question?Little is known about the impact of sex and age on the routine laboratory parameters measured in COVID-19 patients.- What is the bottom line?Our in-depth analysis unraveled distinct disease profiles influenced by age and sex which may underly occurrence of severe disease.- Why read on?This work will help physicians to interpret the disease presentation in COIVD-19 patients according to their age and sex.

To investigate the effects of environmental cleaning and the installation of heat and moisture exchangers (HMEs) to reduce neonatal carbapenem-resistant Acinetobacter baumannii (CRAB) sepsis and colonization as well as antimicrobial use.We conducted a 7-year, quasi-experimental study.All neonates admitted to a neonatal intensive care unit (NICU).We compared the trends for CRAB sepsis and colonization before (period 1, 2011-2013) and after (period 3, 2015-2017) a 12-month intervention period in 2014 (period 2) to incorporate a combination of HME use and sodium hypochlorite cleaning (5,000 ppm in the NICU and 500 ppm in the neonatal environment) using interrupted time series analysis with segmented regression.During the 7-year study period, 3,367 neonates were admitted to the NICU; the prevalence rates of CRAB sepsis and endotracheal CRAB colonization were 0.5 per 1,000 patient days, and 19.4 per 1,000 ventilator days. A comparison of period 1 to period 3 showed significant decreases in the percentages of both CRAB of A. baumannii sepsis (100% versus 11%) and endotracheal colonization (76% vs 52%) following the introduction of disposable HMEs and sodium hypochlorite cleaning (both P.001). In period 3, compared with period 1, segmented regression analysis showed significant reductions in endotracheal CRAB colonization per 1,000 ventilator days (ie, change in level) and both carbapenem and colistin use (changes in both level and slope) (P.001).Interventions featuring environmental cleaning and use of HMEs led to a sustainable reduction of CRAB colonization coupled with a reduction in broad-spectrum antimicrobial use in the NICU.

Human milk microbes play an important role in infant health and disease. Emerging evidence shows that human milk viruses are also transmitted from the mother to the infant via breastfeeding. These viruses include eukaryotic viruses, bacterium-infecting viruses called bacteriophages, and other viral particles. Human milk viruses are instrumental in shaping the infant gut virome and microbiome. Eukaryotic DNA and RNA viruses contribute to pathogenic challenges and protection. Bacteriophages have the ability to kill bacteria or supply them with potentially beneficial gene functions, thereby shaping the microbiome. The early infant virome is dominated by bacteriophages that likely contribute to a highly dynamic microbiome in the early life. There is a critical window of early childhood growth with rapid maturation of metabolic, endocrine, neural, and immune pathways. The colonization of microbes in the infant body during this time plays an important role in the establishment and maturation of these pathways. The virome transmitted via breastfeeding may also be particularly important at these critical time points of immune development. More longitudinal studies of mother-infant pairs will help to better define the human milk virome and their functional impact on the development of the growing infant.

Background The 2011 IDSA/PIDS Clinical Practice Guidelines for the Management of Community-acquired Pneumonia (CAP) in Children Older than 3 months recommended empiric treatment with either ampicillin/penicillin or ceftriaxone based on PCV13 vaccine status and the local antibiotic susceptibilities of IPD isolates. No study has addressed differences in antibiotic susceptibilities for isolates from children with pneumococcal pneumonia (PP) based on PCV13 status. Methods Investigators from 8 US children’s hospitals identified infants and children with IPD between 1/1/2014 and 12/31/2019. IPD was documented by positive cultures from a normally sterile site. PP diagnosis required an abnormal chest radiograph. Clinical data were recorded and isolates analyzed for serotype (ST) by the capsular swelling method and antimicrobial susceptibilities by standard methods. Administration of PCV7/13 was documented through the patient’s medical records, health care provider or a vaccine registry. Fisher Exact was performed; p< 0.05 was significant. Results 690 IPD patients with isolates were available (0–18 y); 24% (166/690) of the isolates were PCV13 STs (ST3-75, ST19F-45, ST19A-36, ST7F-5, other STs-5). The most common non-PCV13 ST isolates were ST35B-60, ST23B-59, ST33F-47, ST22F-43, ST15C-35, ST23A-27, ST15B-26, ST10A-26, ST15A-23. Of non-PCV13 isolates, 41% (217/524) were among the 7 additional STs in PCV20. For children with PP (n=157), the distributions of penicillin (Table) (p=0.8) and ceftriaxone MICs were no different for isolates obtained from children regardless of prior PCV13 doses. Less than 7% of PP isolates were resistant to penicillin (MIC >2 µg/mL). Table. Minimal inhibitory concentrations (MIC) of pneumococcal isolates related to the number of PCV13 doses each patient received prior to pneumococcal pneumonia (PP). Number of PCV13 doses Conclusion PCV13 status should not modify empiric antibiotics for children with suspected pneumococcal CAP. 41% of non-PCV13 IPD isolates were among the 7 additional PCV20 STs. Disclosures Sheldon L. Kaplan, MD, Allergan (Research Grant or Support)Pfizer (Grant/Research Support) Tina Q. Tan, MD, Pfizer (Grant/Research Support, Other Financial or Material Support, Chair, DMSB for PCV20 vaccine) Pia S. Pannaraj, MD, MPH, AstraZeneca (Grant/Research Support)Pfizer (Grant/Research Support)Sanofi Pasteur (Advisor or Review Panel member)

INTRODUCTION: The infant gut microbiome is thought to play a key role in developing metabolic and immunologic pathways. Antibiotics have been shown to disrupt the human microbiome, but the impact they have on infants during this key window of development remains poorly understood. Through this study we further characterize the effect antibiotics have on the gut microbiome of infants by looking at metagenomic sequencing data over time. MATERIALS AND METHODS: Stool samples were collected on infants from a large tertiary care neonatal intensive care unit. After DNA extraction, metagenomics libraries were generated and sequenced. Taxonomic and functional analyses were then performed. Further directed specimen sequencing for fungal species was also performed. RESULTS: A total of 51 stool samples from 25 infants were analyzed: 7 infants were on antibiotics during at least one of their collection time points. Antibiotics given at birth altered the microbiome (PERMANOVA R(2)= 0.044, p=0.002) but later courses did not (R(2)= 0.023, p= 0.114). Longitudinal samples collected while off antibiotics were more similar than those collected during a transition on or off antibiotics (mean Bray-Curtis distance 0.29 vs. 0.63, Wilcoxon p=0.06). Functional analysis revealed four microbial pathways that were disrupted by antibiotics given at-birth (p

Human milk microbes play an important role in infant health and disease. Emerging evidence shows that human milk viruses are also transmitted from the mother to the infant via breastfeeding. These viruses include eukaryotic viruses, bacterium-infecting viruses called bacteriophages, and other viral particles. Human milk viruses are instrumental in shaping the infant gut virome and microbiome. Eukaryotic DNA and RNA viruses contribute to pathogenic challenges and protection. Bacteriophages have the ability to kill bacteria or supply them with potentially beneficial gene functions, thereby shaping the microbiome. The early infant virome is dominated by bacteriophages that likely contribute to a highly dynamic microbiome in the early life. There is a critical window of early childhood growth with rapid maturation of metabolic, endocrine, neural, and immune pathways. The colonization of microbes in the infant body during this time plays an important role in the establishment and maturation of these pathways. The virome transmitted via breastfeeding may also be particularly important at these critical time points of immune development. More longitudinal studies of mother-infant pairs will help to better define the human milk virome and their functional impact on the development of the growing infant.

1. Approximately what percentage of the population is iciHHV-6 positive? Answer: b. Depending on the population, approximately 0.5 to 2% of individuals carry HHV-6 integrated into every cell in their body. 1. Quantitative estimates of HHV-6 viral load in whole blood are NOT affected

BACKGROUND: The 13-valent pneumococcal conjugate vaccine (PCV13) was licensed in the United States in 2010. We describe invasive pneumococcal disease (IPD) in children at 8 children’s hospitals in the US from 2014 to 2017. METHODS: Children with IPD occurring from 2014 to 2017 were identified from a prospective study. Demographic and clinical data, including results of any immune evaluation along with the number and dates of previous pneumococcal conjugate vaccines administered, were recorded on case report forms. Isolate serotypes were determined in a central laboratory. Pneumococcal conjugate vaccine doses were counted if IPD occurred ≥2 weeks after a dose. RESULTS: PCV13 serotypes accounted for 23.9% (115 out of 482) of IPD isolates from 2014 to 2017. Serotypes 3, 19A, and 19F accounted for 91% of PCV13 serotypes. The most common non-PCV13 serotypes were 35B, 23B, 33F, and 22F. An underlying condition was significantly (P < .0001) more common in children with IPD due to non-PCV13 serotypes (200 out of 367, 54.5%) than for children with PCV13 serotypes (27 out of 115, 23.5%). An immune evaluation was undertaken in 28 children who received ≥2 PCV13 doses before IPD caused by a PCV13 serotype. Only 1 was found to have an immunodeficiency. CONCLUSIONS: PCV13 serotypes (especially serotypes 3, 19A, and 19F) continue to account for nearly a quarter of IPD in US children 4 to 7 years after PCV13 was introduced. Underlying conditions are more common in children with non-PCV13 serotype IPD. Immune evaluations in otherwise healthy children with PCV13 serotype IPD despite receiving ≥2 PCV13 doses did not identify an immunodeficiency.

Naegleria fowleri is a thermophilic free-living amoeba that is found in warm, fresh water and causes primary amebic meningoencephalitis (PAM). The following report demonstrates the rapid and destructive clinical features of PAM in an 8-year-old male who presented with severe headaches approximately 12 days after swimming in a hot spring.

CONTEXT:Timely vaccine uptake in children remains suboptimal. Eliminating missed opportunities is key to increasing childhood immunization rates, and hospitalization offers another potential setting to vaccinate.OBJECTIVE:To better understand pediatric inpatient immunization programs, including vaccination rates of inpatients, parental and provider attitudes, barriers to vaccine delivery, and interventions to increase provision of inpatient vaccines.DATA SOURCES:A search was conducted of PubMed, Embase, and Web of Science to identify articles and conference abstracts related to pediatric inpatient immunization.STUDY SELECTION:Inclusion criteria were studies published in English between January 1990 and January 2019 in which pediatric vaccination in the hospital setting was discussed. Findings from 30 articles and conference abstracts were summarized and organized by topic area.DATA EXTRACTION:Abstracts were screened for relevance, articles were read, and themes were identified.RESULTS:Children who are hospitalized have been shown to have lower immunization rates compared with the general population, with 27% to 84% of pediatric inpatients due or overdue for vaccines nationally when verified with official records. Unfortunately, little is done to catch up these children once they have been identified. Access to accurate vaccine histories remains a major barrier in inpatient immunization programs because providers frequently under document and parents over recall a child’s vaccine status. Strategies identified to increase inpatient vaccination included creation of a multidisciplinary immunization team, educational interventions, visual reminders, catch-up vaccine plans, order sets, and nursing-driven screening. When offered inpatient vaccination, a majority of parents accepted immunizations for their children.CONCLUSIONS:Hospitalization may provide an opportunity to augment vaccine uptake. Further research is needed to develop evidence-based strategies to overcome barriers to inpatient vaccination.

Summary Background There is increasing concern that persistent infection of SARS-CoV-2 within immunocompromised hosts could serve as a reservoir for mutation accumulation and subsequent emergence of novel strains with the potential to evade immune responses. Methods We describe three patients with acute lymphoblastic leukemia who were persistently positive for SARS-CoV-2 by real-time polymerase chain reaction. Viral viability from longitudinally-collected specimens was assessed. Whole-genome sequencing and serological studies were performed to measure viral evolution and evidence of immune escape. Findings We found compelling evidence of ongoing replication and infectivity for up to 162 days from initial positive by subgenomic RNA, single-stranded RNA, and viral culture analysis. Our results reveal a broad spectrum of infectivity, host immune responses, and accumulation of mutations, some with the potential for immune escape. Interpretation Our results highlight the need to reassess infection control precautions in the management and care of immunocompromised patients. Routine surveillance of mutations and evaluation of their potential impact on viral transmission and immune escape should be considered. Funding The work was partially funded by The Saban Research Institute at Children’s Hospital Los Angeles intramural support for COVID-19 Directed Research (X.G. and J.D.B.), the Johns Hopkins Center of Excellence in Influenza Research and Surveillance HHSN272201400007C (A.P.), NIH/NIAID R01AI127877 (S.D.B.), NIH/NIAID R01AI130398 (S.D.B.), NIH 1U54CA260517 (S.D.B.), an endowment to S.D.B. from the Crown Family Foundation, an Early Postdoc.Mobility Fellowship Stipend to O.F.W. from the Swiss National Science Foundation (SNSF), and a Coulter COVID-19 Rapid Response Award to S.D.B. L.G. is a SHARE Research Fellow in Pediatric Hematology-Oncology.

BACKGROUND Obesity emerged as a novel risk factor for severe disease during the 2009 H1N1 influenza pandemic. Murine studies indicate that obesity is associated with ineffective response to influenza vaccine, but few human studies exist. We aimed to determine if influenza vaccine is protective against laboratory-confirmed influenza in obese children. METHODS Body mass index, vaccination status, and laboratory-confirmed influenza data were analyzed from a previously conducted prospective study in which active surveillance for influenza-like illness was conducted in 8 elementary schools in Los Angeles County during the 2010-2011 influenza season. Polymerase-chain reaction (PCR) was performed on combined nose/throat swabs collected from children with influenza-like illness at presentation to the school nurse or during absenteeism. RESULTS Of 4260 children with height/weight data, 1191 (28.0%) were obese (body mass index ≥95th percentile). Respiratory specimens were obtained from 858 (20.1%) children. Unvaccinated obese compared with vaccinated obese children acquired 3 times more PCR-confirmed influenza (62 vs. 17 per 1000 children, P = 0.003) and missed more school days (4.6 vs. 3.2 per 100 school days, P < 0.001) during influenza season. Obese children with PCR-confirmed influenza were more likely to present with cough (86.2 vs. 72.4%, P = 0.030) and missed more school per episode (2.4 vs.1.9 days, P = 0.023) compared with nonobese children. Among vaccinated children, rates of PCR-confirmed influenza were similar in obese and nonobese children (17 vs. 20 per 1000 children, P = 0.77). CONCLUSIONS Obese children with PCR-confirmed influenza suffered from more cough and missed more school days than their nonobese peers. Influenza vaccination protected obese children against PCR-proven influenza illness.