Durability of Original Monovalent mRNA Vaccine Effectiveness Against COVID-19 Omicron-Associated Hospitalization in Children and Adolescents - United States, 2021-2023

Pediatric COVID-19 vaccination is effective in preventing COVID-19-related hospitalization, but duration of protection of the original monovalent vaccine during SARS-CoV-2 Omicron predominance merits evaluation, particularly given low coverage with updated COVID-19 vaccines. During December 19, 2021-October 29, 2023, the Overcoming COVID-19 Network evaluated vaccine effectiveness (VE) of ≥2 original monovalent COVID-19 mRNA vaccine doses against COVID-19-related hospitalization and critical illness among U.S. children and adolescents aged 5-18 years, using a case-control design. Too few children and adolescents received bivalent or updated monovalent vaccines to separately evaluate their effectiveness. Most case-patients (persons with a positive SARS-CoV-2 test result) were unvaccinated, despite the high frequency of reported underlying conditions associated with severe COVID-19. VE of the original monovalent vaccine against COVID-19-related hospitalizations was 52% (95% CI = 33%-66%) when the most recent dose was administered <120 days before hospitalization and 19% (95% CI = 2%-32%) if the interval was 120-364 days. VE of the original monovalent vaccine against COVID-19-related hospitalization was 31% (95% CI = 18%-43%) if the last dose was received any time within the previous year. VE against critical COVID-19-related illness, defined as receipt of noninvasive or invasive mechanical ventilation, vasoactive infusions, extracorporeal membrane oxygenation, and illness resulting in death, was 57% (95% CI = 21%-76%) when the most recent dose was received <120 days before hospitalization, 25% (95% CI = -9% to 49%) if it was received 120-364 days before hospitalization, and 38% (95% CI = 15%-55%) if the last dose was received any time within the previous year. VE was similar after excluding children and adolescents with documented immunocompromising conditions. Because of the low frequency of children who received updated COVID-19 vaccines and waning effectiveness of original monovalent doses, these data support CDC recommendations that all children and adolescents receive updated COVID-19 vaccines to protect against severe COVID-19.

Characteristics and Clinical Outcomes of Vaccine-Eligible US Children Under-5 Years Hospitalized for Acute COVID-19 in a National Network

BACKGROUND AND OBJECTIVES

In June 2022, the mRNA COVID-19 vaccination was recommended for young children. We examined clinical characteristics and factors associated with vaccination status among vaccine-eligible young children hospitalized for acute COVID-19.

METHODS

We enrolled inpatients 8 months to <5 years of age with acute community-acquired COVID-19 across 28 US pediatric hospitals from September 20, 2022 to May 31, 2023. We assessed demographic and clinical factors, including the highest level of respiratory support, and vaccination status defined as unvaccinated, incomplete, or complete primary series [at least 2 (Moderna) or 3 (Pfizer-BioNTech) mRNA vaccine doses ≥14 days before hospitalization].

RESULTS

Among 597 children, 174 (29.1%) patients were admitted to the intensive care unit and 75 (12.6%) had a life-threatening illness, including 51 (8.5%) requiring invasive mechanical ventilation. Children with underlying respiratory and neurologic/neuromuscular conditions more frequently received higher respiratory support. Only 4.5% of children hospitalized for COVID-19 (n = 27) had completed their primary COVID-19 vaccination series and 7.0% (n = 42) of children initiated but did not complete their primary series. Among 528 unvaccinated children, nearly half (n = 251) were previously healthy, 3 of them required extracorporeal membrane oxygenation for acute COVID-19 and 1 died.

CONCLUSIONS

Most young children hospitalized for acute COVID-19, including most children admitted to the intensive care unit and with life-threatening illness, had not initiated COVID-19 vaccination despite being eligible. Nearly half of these children had no underlying conditions. Of the small percentage of children who initiated a COVID-19 primary series, most had not completed it before hospitalization.

Effectiveness of Maternal mRNA COVID-19 Vaccination During Pregnancy Against COVID-19-Associated Hospitalizations in Infants Aged <6 Months During SARS-CoV-2 Omicron Predominance - 20 States, March 9, 2022-May 31, 2023

Infants aged <6 months are not eligible for COVID-19 vaccination. Vaccination during pregnancy has been associated with protection against infant COVID-19-related hospitalization. The Overcoming COVID-19 Network conducted a case-control study during March 9, 2022-May 31, 2023, to evaluate the effectiveness of maternal receipt of a COVID-19 vaccine dose (vaccine effectiveness [VE]) during pregnancy against COVID-19-related hospitalization in infants aged <6 months and a subset of infants aged <3 months. VE was calculated as (1 - adjusted odds ratio) x 100% among all infants aged <6 months and <3 months. Case-patients (infants hospitalized for COVID-19 outside of birth hospitalization and who had a positive SARS-CoV-2 test result) and control patients (infants hospitalized for COVID-19-like illness with a negative SARS-CoV-2 test result) were compared. Odds ratios were determined using multivariable logistic regression, comparing the odds of receipt of a maternal COVID-19 vaccine dose (completion of a 2-dose vaccination series or a third or higher dose) during pregnancy with maternal nonvaccination between case- and control patients. VE of maternal vaccination during pregnancy against COVID-19-related hospitalization was 35% (95% CI = 15%-51%) among infants aged <6 months and 54% (95% CI = 32%-68%) among infants aged <3 months. Intensive care unit admissions occurred in 23% of all case-patients, and invasive mechanical ventilation was more common among infants of unvaccinated (9%) compared with vaccinated mothers (1%) (p = 0.02). Maternal vaccination during pregnancy provides some protection against COVID-19-related hospitalizations among infants, particularly those aged <3 months. Expectant mothers should remain current with COVID-19 vaccination to protect themselves and their infants from hospitalization and severe outcomes associated with COVID-19.

Optimizing Education During Pediatric Resident Mock Code Sessions

INTRODUCTION

Most pediatric residents have limited opportunities to manage cardiac arrest. We used simulation to fill that educational void. Given work hours and other obligations, resident education sessions must be high-yield. We examined the effectiveness of adding varying amounts of formal education to a mock code session on resident knowledge and confidence in managing pediatric cardiac arrest compared with participation alone.

METHODS

Convenient groups of 3 to 8 pediatric residents completed a simulation session with the identical scenario: a 3-month-old infant with pulseless ventricular tachycardia and then pulseless electrical activity. All residents completed pretests and posttests, which consisted of open-ended knowledge questions from the American Heart Association Pediatric Advanced Life Support guidelines and confidence Likert scale assessments. Resident groups were assigned to 1 of 3 educational models: experiential-only: participation in the mock, traditional: mock code participation with standardized education after the mock code, or reinforced: standardized education before and after mock code participation.

RESULTS

Ninety-five residents participated. Collectively, residents demonstrated a median 2-point (interquartile range, 1-4) increase in knowledge (test maximum score, 10) after they attended a mock code simulation session ( P < 0.0001); however, there were no statistically significant differences noted between educational modalities. All residents also demonstrated a 4-point median increase in confidence (test maximum score, 25) after completing their simulation session (interquartile range, 3-6) ( P < 0.001), but no differences were seen by type or amount of accompanying education.

CONCLUSIONS

Residents had gains in confidence and knowledge of pediatric cardiac arrest management after participation in the mock code. Formal educational sessions and reinforced formal education sessions accompanying the mock code did not significantly increase knowledge or confidence.

Factors Associated With COVID-19 Non-vaccination in Adolescents Hospitalized Without COVID-19

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 < .01) and resided in areas with higher social vulnerability index (SVI) scores (median 0.6 vs 0.5, p < .001) than vaccinated adolescents. Residence in the Midwest [aOR 2.60 (95% CI: 1.80, 3.79)] or South [aOR 2.49 (95% CI: 1.77, 3.54)] US census regions, rarely or never receiving influenza vaccine [aOR 5.31 (95% CI: 3.81, 7.47)], and rarely or never taking precautions against COVID-19 [aOR 3.17 (95% CI: 1.94, 5.31)] were associated with non-vaccination against COVID-19.

CONCLUSIONS

Efforts to increase COVID-19 vaccination of adolescents should focus on persons with geographic, socioeconomic, and medical risk factors associated with non-vaccination.

BNT162b2 mRNA Vaccination Against Coronavirus Disease 2019 is Associated With a Decreased Likelihood of Multisystem Inflammatory Syndrome in Children Aged 5-18 Years-United States, July 2021 - April 2022

BACKGROUND

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.

METHODS

In a multicenter, case-control, public health investigation of children ages 5-18 years hospitalized from 1 July 2021 to 7 April 2022, we compared the odds of being fully vaccinated (2 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.

RESULTS

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 (adjusted OR [aOR]: .16; 95% CI: .10-.26), including among children ages 5-11 years (aOR: .22; 95% CI: .10-.52), ages 12-18 years (aOR: .10; 95% CI: .05-.19), and during the Delta (aOR: .06; 95% CI: .02-.15) and Omicron (aOR: .22; 95% CI: .11-.42) variant-predominant periods. This association persisted beyond 120 days after the second dose (aOR: .08; 95% CI: .03-.22) in 12-18-year-olds. Among all MIS-C case-patients, 187 (62%) required intensive care unit admission and 280 (92%) vaccine-eligible case-patients were unvaccinated.

CONCLUSIONS

Vaccination with 2 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.

Maternal Vaccination and Risk of Hospitalization for Covid-19 among Infants

BACKGROUND

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.

METHODS

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).

RESULTS

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.

CONCLUSIONS

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.).

BNT162b2 Protection against the Omicron Variant in Children and Adolescents

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.).

Effectiveness of BNT162b2 Vaccine against Critical Covid-19 in Adolescents

BACKGROUND

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.

METHODS

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).

RESULTS

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.

CONCLUSIONS

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.).

Effectiveness of Maternal Vaccination with mRNA COVID-19 Vaccine During Pregnancy Against COVID-19-Associated Hospitalization in Infants Aged <6 Months - 17 States, July 2021-January 2022

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.§ Infants are at risk for life-threatening complications from COVID-19, including acute respiratory failure (1). Evidence from other vaccine-preventable diseases suggests that maternal immunization can provide protection to infants, especially during the high-risk first 6 months of life, through passive transplacental antibody transfer (2). Recent studies of COVID-19 vaccination during pregnancy suggest the possibility of transplacental transfer of SARS-CoV-2-specific antibodies that might provide protection to infants (3-5); however, no epidemiologic evidence currently exists for the protective benefits of maternal immunization during pregnancy against COVID-19 in infants. The Overcoming COVID-19 network conducted a test-negative, case-control study at 20 pediatric hospitals in 17 states during July 1, 2021-January 17, 2022, to assess effectiveness of maternal completion of a 2-dose primary mRNA COVID-19 vaccination series during pregnancy against COVID-19 hospitalization in infants. Among 379 hospitalized infants aged <6 months (176 with COVID-19 [case-infants] and 203 without COVID-19 [control-infants]), the median age was 2 months, 21% had at least one underlying medical condition, and 22% of case- and control-infants were born premature (<37 weeks gestation). Effectiveness of maternal vaccination during pregnancy against COVID-19 hospitalization in infants aged <6 months was 61% (95% CI = 31%-78%). Completion of a 2-dose mRNA COVID-19 vaccination series during pregnancy might help prevent COVID-19 hospitalization among infants aged <6 months.

Effectiveness of BNT162b2 (Pfizer-BioNTech) mRNA Vaccination Against Multisystem Inflammatory Syndrome in Children Among Persons Aged 12-18 Years - United States, July-December 2021

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),§ and real-world studies in persons aged 12-18 years demonstrated high vaccine effectiveness (VE) against severe COVID-19 (6). Recent evidence suggests that COVID-19 vaccination is associated with lower MIS-C incidence among adolescents (7); however, VE of the 2-dose Pfizer-BioNTech regimen against MIS-C has not been evaluated. The effectiveness of 2 doses of Pfizer-BioNTech vaccine received ≥28 days before hospital admission in preventing MIS-C was assessed using a test-negative case-control design¶ among hospitalized patients aged 12-18 years at 24 pediatric hospitals in 20 states** during July 1-December 9, 2021, the period when most MIS-C patients could be temporally linked to SARS-CoV-2 B.1.617.2 (Delta) variant predominance. Patients with MIS-C (case-patients) and two groups of hospitalized controls matched to case-patients were evaluated: test-negative controls had at least one COVID-19-like symptom and negative SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) or antigen-based assay results, and syndrome-negative controls were hospitalized patients without COVID-19-like illness. Among 102 MIS-C case-patients and 181 hospitalized controls, estimated effectiveness of 2 doses of Pfizer-BioNTech vaccine against MIS-C was 91% (95% CI = 78%-97%). All 38 MIS-C patients requiring life support were unvaccinated. Receipt of 2 doses of the Pfizer-BioNTech vaccine is associated with a high level of protection against MIS-C in persons aged 12-18 years, highlighting the importance of vaccination among all eligible children.

Effectiveness of Pfizer-BioNTech mRNA Vaccination Against COVID-19 Hospitalization Among Persons Aged 12-18 Years - United States, June-September 2021

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.

Missed Opportunity: Why Parents Refuse Influenza Vaccination for Their Hospitalized Children

BACKGROUND AND OBJECTIVES

Hospitals are required to screen and administer the influenza vaccine to all admitted children unless contraindicated or refused by parents, yet vaccination rates remain low. Our goal was to examine reasons for refusal among pediatric patients admitted during influenza season.

METHODS

All children age 6 months to 18 years admitted to 2 network community hospitals from October 1, 2013 to March 31, 2014, without contraindications, were offered influenza vaccination prior to discharge. Parents who refused vaccination were asked their reason for refusal. Chi-square tests and logistic regression were used to determine factors associated with refusing the vaccine in the inpatient setting.

RESULTS

Three hundred twenty-five of 786 unique patients admitted during influenza season were eligible for vaccination. Of these, 49.8% refused. Parents of females, whites, and those with private insurance were more likely to refuse vaccination. Patients whose immunization status was otherwise up to date were more likely to accept (Odds Ratio 2.39, 95% Confidence Interval 1.05-5.41). Commonly cited reasons for refusal were: preference to have vaccination by the primary care provider (24.1%), concern for side effects (16.1%), not wanting vaccination (13%), doubt in efficacy (8%), concern that the child was already sick (6.8%), no prior influenza vaccination (6.7%) and feeling that it was not needed (5.6%).

CONCLUSIONS

Hospitalization during influenza season provides an opportunity for health-care providers to educate families about influenza and vaccinate patients if appropriate. However, nearly half of parents of eligible children declined vaccination. More study is required to determine strategies that can increase influenza vaccination acceptance.

Parental presence on pediatric intensive care unit rounds

OBJECTIVE

To comprehensively evaluate the effect of parental presence on pediatric intensive care unit rounds.

STUDY DESIGN

A prospective, observational and survey-based study comprised of (1) observation of rounds (2) "rounding event assessments" (brief surveys specific to 1 rounding event, completed by health care providers [HCPs] n = 375) (3) qualitative interviews with parents (36 who joined rounds and 16 who elected not to join), and (4) qualitative written surveys from HCPs (63 nurses, 39 doctors).

RESULTS

Eighty-one percent of parents who chose to join rounds reported that participation increased their overall satisfaction with their child's care. In 57% of rounding events, at least 1 HCP learned new, pertinent information from the parents. However, in 32% of rounding events, at least 1 HCP believed parental presence limited discussion. Forty-seven percent of parents who participated in rounds and 88% of those who chose not to participate volunteered that participation has the potential to increase parental confusion and anxiety (P = .02).

CONCLUSIONS

Most parents and physicians agree that parents should be invited to participate on rounds. Parents report increased satisfaction from participation, and parents provide new information when on rounds. However, parental presence may limit discussion during rounds which may adversely affect patient care.

Light regulation of retinal dopamine that is independent of melanopsin phototransduction

Light-dependent release of dopamine (DA) in the retina is an important component of light-adaptation mechanisms. Melanopsin-containing inner retinal photoreceptors have been shown to make physical contacts with DA amacrine cells, and have been implicated in the regulation of the local retinal environment in both physiological and anatomical studies. Here we determined whether they contribute to photic regulation of DA in the retina as assayed by the ratio of DA with its primary metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), and by c-fos induction in tyrosine hydroxylase (TH)-labelled DA amacrine cells. Light treatment (approximately 0.7 log W/m(2) for 90 min) resulted in a substantial increase in DA release (as revealed by an increase in the DOPAC : DA ratio), as well as widespread induction of nuclear c-fos in DA amacrine cells in wild-type mice and in mice lacking melanopsin (Opn4(-/-)). Light-induced DA release was also retained in mice lacking rod phototransduction (Gnat1(-/-)), although the magnitude of this response was substantially reduced compared with wild-types, as was the incidence of light-dependent nuclear c-fos in DAergic amacrines. By contrast, the DAergic system of mice lacking both rods and cones (rd/rd cl) showed no detectable light response. Our data suggest that light regulation of DA, a pivotal retinal neuromodulator, originates primarily with rods and cones, and that melanopsin is neither necessary nor sufficient for this photoresponse.

The effect of calcium supplementation on bone density in premenarcheal females: a co-twin approach

The age and developmental stage at which calcium supplementation produces the greatest bone effects remain controversial. We tested the hypothesis that calcium supplementation may improve bone accrual in premenarcheal females. Fifty-one pairs of premenarcheal female twins (27 monozygotic and 24 dizygotic; mean +/- sd age, 10.3 +/- 1.5 yr) participated in a randomized, single-blind, placebo-controlled trial with one twin of each pair receiving a 1200-mg calcium carbonate (Caltrate) supplement. Areal bone mineral density (aBMD) was measured at baseline and 6, 12, 18 and 24 months. There were no within-pair differences in height, weight, or calcium intake at baseline. Calcium supplementation was associated (P < 0.05) with increased aBMD compared with placebo, adjusted for age, height, and weight at the following time points from baseline: total hip, 6 months (1.9%), 12 months (1.6%), and 18 months (2.4%); lumbar spine, 12 months (1.0%); femoral neck, 6 months (1.9%). Adjusted total body bone mineral content was higher in the calcium group at 6 months (2.0%), 12 months (2.5%), 18 months (4.6%), and 24 months (3.7%), respectively (all P < 0.001). Calcium supplementation was effective in increasing aBMD at regional sites over the first 12-18 months, but these gains were not maintained to 24 months.

Blood lead-urine lead relationships in adults and children

To determine the potential for using instead of blood as an indicator of lead exposure, especially in infants, lead concentrations and high-precision lead isotopic measurements have been compared in venous blood and "spot" urine (n > 260 from 182 different subjects) collected within the same 24-h period. Physiological conditions for the children and most of the adults were considered to be in a steady-state between body stores and lead in the environment. In the case of some adults, conditions were initially not steady-state because exposure conditions changed (for example, subjects moved to a country with lead of different isotopic composition.) There was a high correlation (r2 = ) between the blood and urine measurements of the isotope ratios but about 10% of measurements were outliers--the blood and urine measurements were further apart than was consistent with the measurement error that was generally obtained. The discrepancy was usually found to be associated with the urine measurement and was attributed to contamination during sampling. Weekly urine and monthly blood monitoring of an adult male over a 24-month period showed and excellent correlations, although the standard deviations were about an order of magnitude higher than the precision measured for replicate analyses of a single blood or urine sample. "Spot" urine analyses for two male subjects gave excellent agreement with 24-h urine samples. Standard deviations of the spot analyses were of similar order to those in the 24-month monitored subject. In cases where female adults from Eastern Europe migrated to Australia, there was generally a more rapid exchange of skeletal lead with Australian environmental lead in urine compared with blood. These data do not support a differential partitioning of endogenous lead into the plasma. At this stage, isotopic measurements of urine can be used as a proxy for isotopic measurements in blood. However, lead concentrations in blood and in urine are only weakly related. Concentrations of lead in urine cannot serve to predict concentrations of lead in blood, particularly at the lower range of exposures, for example, at blood concentrations less than 10 microgram/d1.

Modulation of fecal markers relevant to colon cancer risk: a high-starch Chinese diet did not generate expected beneficial changes relative to a Western-type diet

In a randomized, crossover dietary intervention study, 12 Australians (of white descent) consumed a diet typical of low-income communities in China and an average Australian diet so that effects on fecal markers thought to be relevant to colon cancer risk could be compared. The Chinese diet contained 35.3 g starch/MJ daily [including 2 g resistant starch (RS)/MJ and 1.5 g nonstarch polysaccharides (NSPs)/MJ]; the Australian diet contained 12 g starch/MJ daily (including 0.8 g RS and 2.7 g NSPs/MJ). Subjects followed each diet for 3 wk. Serum cholesterol concentrations were significantly lower after the low-fat, high-starch Chinese diet than after the Australian diet (mean +/- SEM: 4.17 +/- 0.30 compared with 5.04 +/- 0.28 mmol/L, respectively, P < 0.05), a difference indicative of dietary compliance. Fecal pH was lower after the Chinese diet (6.51 +/- 0.04) than after the Australian diet (6.63 +/- 0.05; P < 0.05). For all other fecal markers examined, however, the Chinese diet produced less favorable changes, including lower fecal bulk (86 +/- 11 compared with 141 +/- 20 g wet wt/d, P < 0.01), slower transit through the gut (69 +/- 6 compared with 56 +/- 7 h, P = 0.06), lower fecal concentrations of short-chain fatty acids [72.8 +/- 7.3 compared with 98 +/- 7.6 mmol/L (including butyrate: 12.2 +/- 1.3 compared with 18.4 +/- 2.3 mmol/L), P < 0.05], and higher fecal concentrations of potentially damaging ammonia (540 +/- 50 compared with 450 +/- 40 mg/L, P < 0.01) and phenols (109.2 +/- 13.2 compared with 68.5 +/- 12.9 mg/L, P < 0.01). These results suggest that consumption of a high-starch diet alone is insufficient to reduce the risk of developing colon cancer.

Mobilization of lead from the skeleton during the postnatal period is larger than during pregnancy

A cohort of 15 immigrant females to Australia and 7 native Australian controls were monitored on a monthly basis with high-precision lead isotopic methods during gestation and for 6 months after pregnancy to determine the extent of lead mobilization from the maternal skeleton. Quarterly environmental samples of house dust, drinking water, urban air, gasoline, and a 6-day duplicate diet were also measured. The geometric mean blood lead concentration for the immigrant females on arrival in Australia was 3.0 microg/dl (range: 1.9 to 20 microg/dl), and for the Australian controls was 3.1 gm/dl (range: 1.9 to 4.3 microg/dl). During gestation and after pregnancy, blood lead concentrations varied, with mean individual changes of -14% to 83%. For the immigrant subjects, the percentage change in blood lead concentration was significantly greater during the postpregnancy period than during the 2nd and 3rd trimesters (p < 0.001). Skeletal contribution to blood lead, based on the isotopic composition for the immigrant subjects, increased in an approximately linear manner during pregnancy. The mean increases for each individual during pregnancy varied from 26% to 99%. Skeletal lead contribution to blood lead was significantly greater (p < 0.001) during the postpregnancy period than during the 2nd and 3rd trimesters. The contribution of skeletal lead to blood lead during the postpregnancy period remained essentially constant at the increased level of lead mobilization, although the duration of breastfeeding varied from 1 week to more than 6 months. The increased contribution of skeletal lead to blood lead during the postpregnancy period is attributed to increased mobilization of lead from maternal skeletal stores during lactation. The increased contribution of skeletal lead both during pregnancy and in the postpregnancy period is consistent with increased bone resorption, and may be associated with an inadequate calcium intake observed in quarterly 6-day duplicate diets. Mobilization of skeletal lead stores represents a potentially important source of perinatal lead intake and accumulation in the developing fetus. Only two subjects consumed dietary supplements for calcium, and their mobilization of lead from the skeleton to the blood was the lowest of all the subjects. These two subjects' use of calcium supplements may have reduced mobilization of skeletal mineral stores to supply the calcium needs of pregnancy and lactation. Calcium supplementation may be an important means of limiting fetal exposure to lead.

Contribution of tissue lead to blood lead in adult female subjects based on stable lead isotope methods

Public health and medical recommendations on prevention of lead toxicity rely on use of blood lead concentrations to assess lead exposure and predict onset of adverse health effects. Blood lead levels have generally been thought to reflect recent environmental lead exposures. However, tissue lead stores are accumulated over a long time period (i.e., years). These tissue stores, primarily from bone, can be remobilized as part of both normal physiologic and pathologic processes. Although chemical analyses do not differentiate lead isotopes, mass spectrometric determinations can differentiate the quantities of stable lead isotopes present in particular samples (e.g., lead 207, lead 206, lead 204, and lead 208). Selected geographic locations may have distinct isotopic profiles. For example, on mainland Australia the 206Pb/204Pb ratios reported in both environmental lead sources and blood samples are typically less than 17.0. By contrast, stable lead isotope profiles in blood samples of adult women immigrating from Eastern Europe and the former Soviet Union usually have 206Pb/204Pb ratios greater than 17.5 and as high as 18.5 on entry into Australia. Longitudinal monitoring of blood samples to determine stable lead isotope profiles by mass spectrometry and chemical analyses of blood samples for total lead content were conducted over a 300-day period. These data show that between 45% and 70% of lead in blood comes from long-term tissue lead stores. Recognition that the predominant source of lead in blood was tissue stores rather than the contemporaneous environment should greatly modify recommendations on use of blood lead to monitor occupational or environmental interventions. In addition, internal biokinetics of lead, documented through presence of tissue lead in blood, underlie the long-term health risks of lead exposure. Transfer of lead to the fetus from maternal tissue stores represents a special area of concern.

Statistical discriminant analysis of arrhythmias using intracardial electrograms

The problem of classifying ventricular arrhythmias from intracardial electrograms is considered. Standard statistical discrimination procedures are applied using a simple parametric model for the shape of the pulse near its peak. This approach makes simultaneous use of the model parameters, has well known statistical properties, and involves computations that can be carried out efficiently. Preliminary analyses of real data sets, using both linear and quadratic discrimination functions, yield promising results.

Insulin syringes: dangers of dead space

To assess the accuracy and reproducibility of various U100 insulin syringes in the hands of diabetics, we devised a method to measure individual insulins injected from the syringe. We found alarming inaccuracies with dead-space-containing syringes when two insulins were mixed in the syringe before injection; these errors exceeded 100% with low doses. Reproducibility of dose was also poor with dead-space syringes. Syringes with minimal dead space overcome these problems and we recommend that all diabetics who mix insulins should use these syringes.