Steep Hierarchies without Skew? Modeling How Ecology and Decision-Making Shape Despotism of Relationships.

AbstractAnimals can form dominance relationships that vary from highly unequal, or despotic, to egalitarian, and this variation likely impacts the fitness of individuals. How and why these differences in relationships and fitness exist among groups, populations, and species has been the subject of much debate. Here, we investigated the influence of two major factors: (1) spatial resource distribution and (2) the presence or absence of winner-loser effects. To determine the effects of these factors, we built an agent-based model that represented 10 agents directly competing over food resources on a simple landscape. By varying the food distribution and using either asymmetry of strength or experience, we contrasted four scenarios from which we recorded attack decisions, fight outcomes, and individual energy intake to calculate dominance hierarchy steepness and energetic skew. Surprisingly, resource distribution and winner-loser effects did not have the predicted effects on hierarchy steepness. However, skew in energy intake arose when resources were distributed heterogeneously, despite hierarchy steepness frequently being higher in the homogeneous resource scenarios. Thus, this study confirms some decades-old predictions about feeding competition but also casts doubt on the ability to infer energetic consequences from observations of agonistic interactions.

Genome Sequences of Four Subcluster L2 Mycobacterium Phages, Finemlucis, Miley16, Wilder, and Zakai.

Four subcluster L2 mycobacteriophages, Finemlucis, Miley16, Wilder, and Zakai, that infect Mycobacterium smegmatis mc2155 were isolated. The four phages are closely related to each other and code for 12 to 14 tRNAs and 130 to 132 putative protein-coding genes, including tyrosine integrases, cro, immunity repressors, and excise genes involved in the establishment of lysogeny.

Febrile Seizure Risk After Vaccination in Children 6 to 23 Months.

BACKGROUND AND OBJECTIVE: An increased risk of febrile seizure (FS) was identified with concomitant administration of trivalent inactivated influenza vaccine (IIV3) and pneumococcal conjugate vaccine (PCV) 13-valent during the 2010-2011 influenza season. Our objective was to determine whether concomitant administration of IIV3 with other vaccines affects the FS risk. METHODS: We examined the risk of FS 0 to 1 day postvaccination for all routinely recommended vaccines among children aged 6 through 23 months during a period encompassing 5 influenza seasons (2006-2007 through 2010-2011). We used a population-based self-controlled risk interval analysis with a control interval of 14 to 20 days postvaccination. We used multivariable regression to control for receipt of concomitant vaccines and test for interaction between vaccines. RESULTS: Only PCV 7-valent had an independent FS risk (incidence rate ratio [IRR], 1.98; 95% confidence interval [CI], 1.00 to 3.91). IIV3 had no independent risk (IRR, 0.46; 95% CI, 0.21 to 1.02), but risk was increased when IIV3 was given with either PCV (IRR, 3.50; 95% CI, 1.13 to 10.85) or a diphtheria-tetanus-acellular-pertussis (DTaP)-containing vaccine (IRR, 3.50; 95% CI, 1.52 to 8.07). The maximum estimated absolute excess risk due to concomitant administration of IIV3, PCV, and DTaP-containing vaccines compared with administration on separate days was 30 FS per 100 000 persons vaccinated. CONCLUSIONS: The administration of IIV3 on the same day as either PCV or a DTaP-containing vaccine was associated with a greater risk of FS than when IIV3 was given on a separate day. The absolute risk of postvaccination FS with these vaccine combinations was small.

Risk of Herpes Zoster and Disseminated Varicella Zoster in Patients Taking Immunosuppressant Drugs at the Time of Zoster Vaccination.

OBJECTIVE: To determine the risks associated with zoster vaccine when administered to patients taking immunosuppressant medications. PATIENTS AND METHODS: Patients enrolled in 1 of 7 managed care organizations affiliated with the Vaccine Safety Datalink between January 1, 2006, and December 31, 2009, were eligible. The exposure of interest was zoster vaccination in patients with current or remote immunosuppressant drug use. The primary outcomes were disseminated varicella zoster virus (VZV) and herpes zoster in the 42 days after vaccination. Automated data were collected on immunosuppressant drugs and baseline medical conditions. A logistic regression model using inverse probability treatment weights was used to estimate the odds of developing VZV or herpes zoster. RESULTS: A total of 14,554 individuals had an immunosuppressant medication dispensed around the time of vaccination, including 4826 with current use and 9728 with remote use. Most patients were taking low-dose corticosteroids. No cases of disseminated VZV were found in the current or remote users. The risk of herpes zoster was elevated in the 42 days after vaccination in current vs remote users (adjusted odds ratio, 2.99; 95% CI, 1.58-5.70). CONCLUSION: We found that patients taking immunosuppressant medications at the time of vaccination had a modest increased risk of herpes zoster in the 42 days after vaccination. The development of herpes zoster within 42 days after vaccination suggests that this is more likely due to reactivation of latent zoster virus than dissemination of the vaccine-derived varicella virus. These findings support the current zoster vaccination guidelines.

Inpatient admission for febrile seizure and subsequent outcomes do not differ in children with vaccine-associated versus non-vaccine associated febrile seizures.

INTRODUCTION: Recent data suggest that the risk factors for febrile seizure (FS) can differ depending on whether the FS was vaccine-associated (VA) or not. As such, there also may be differences in the risk of inpatient admission and/or the incidence of FS-related subsequent outcomes following the index FS depending on whether it was VA or non-vaccine associated (NVA). This could have useful clinical implications including caregiver education and planning for follow-up care. METHODS: This cohort study consisted of 3348 children who experienced an index FS between 6 months up to 3 years of age from July 1, 2003 through December 31, 2011. The index FS was determined to be VA-FS or NVA-FS; inpatient admission for FS, recurrent FS, and diagnosis of epilepsy were compared between exposure groups. Hazard ratios and relative risk estimates comparing between VA-FS and NVA-FS were estimated by Cox proportional models and Robust Poisson regression models, adjusted for race, sex, age at first FS, birth weight, gestational age, maternal age, and 1- and 5-min Apgar scores. RESULTS: The mean age at index FS was 1.5 years; the mean length of follow-up was 2.3 years. Of all index FS, 383 (11.4%) were VA and 2965 were NVA. Among index FS, 264 (7.9%) were admitted as inpatients. Subsequently, 703 (21.0%) children developed at least one recurrent FS, where the number of recurrences ranged from 0 to 9 events. Overall, 144 (4.3%) children were diagnosed with epilepsy during the follow-up period. In adjusted analyses, VA-FS did not differ in the risk for any of the outcomes of interest compared with NVA-FS. DISCUSSION: The risk of hospitalization for index FS or select subsequent FS outcomes did not differ between VA or NVA-FS. This suggests that the follow-up care of children with VA-FS does not warrant attention beyond that for NVA-FS.

Exploring the risk factors for vaccine-associated and non-vaccine associated febrile seizures in a large pediatric cohort.

INTRODUCTION: It is not known whether there are underlying physiologic or immunologic differences between febrile seizures (FS) triggered by vaccines versus other causes. Furthermore, while secular and individual-level factors have been associated with FS risk, they are rarely evaluated simultaneously. METHODS: Subjects included members of Kaiser Permanente Southern California aged 6 months to 3 years from July 1, 2003-December 31, 2011. Primary outcome was first diagnosis of FS. Vaccine-associated (VA) FS were defined as those occurring from day 0 to day 15 following any vaccine; non-vaccine associated (NVA) FS were those outside this period. We compared incidence rates of VA-FS versus NVA-FS. Poisson regression was used to assess the association between FS and secular and individual-level factors. We also evaluated interactions between vaccine exposure and each model covariate on the risk of FS. RESULTS: Among 265,275 children, 3348 FS were identified; 383(11%) were VA-FS, and 2965(89%) were NVA-FS. Incidence rates were 2.73 and 2.05 per 100,000 person-days for VA-FS and NVA-FS, respectively. Multivariable analyses confirmed previously reported increased risk of FS by age, low gestational age, and winter months. Increased risk was also associated with VA exposure (RR=1.63[95% CI: 1.27-2.11]), non-White race/ethnicity vs. White (African-American RR=1.41[1.22-1.63]; Asian RR=1.58[1.40-1.79]; Hispanic RR=1.60[1.47-1.75]), and maternal age 29 years or less vs. 40+ years (≤ 19 years RR=1.28[1.00-1.65]; 20-29 years RR=1.21[1.02-1.42]). Females were at lower risk of NVA-FS (RR=0.77[0.72-0.83]), but were similar to males for VA-FS (RR=0.97[0.79-1.19]). Children with low 1 min Apgar scores (≤ 3) had increased risk of VA-FS (RR=3.40[1.86-6.22]), but no increased risk for NVA-FS (RR=1.05[0.69-1.60]) compared to children with normal Apgar scores (≥ 7). DISCUSSION: This study suggests that there may be immunogenetic differences underlying VA-FSs compared with other FSs. However, further studies are needed. An understanding of the mechanisms behind these findings may help improve vaccine design or policies.

Safety of the yellow Fever vaccine: a retrospective study.

BACKGROUND: Yellow fever (YF) vaccine is considered safe; however, severe illness and death following vaccination have been reported. METHODS: Vaccine Safety Datalink (VSD) and US Department of Defense (DoD) data were used to identify adverse reactions following YF vaccination. Within the VSD, YF-vaccine-exposed subjects were compared to age-, site-, and gender-matched unexposed subjects. YF-vaccine-exposed DoD subjects were studied using a risk-interval design. For both cohorts, ICD-9 codes were analyzed for allergic and local reactions, mild systemic reactions, and possible visceral and neurologic adverse events (AEs). RESULTS: The VSD cohort received 47,159 doses from 1991 through 2006. The DoD cohort received 1.12 million doses from 1999 through 2007. Most subjects received other vaccines simultaneously. In the VSD cohort, rates of allergic, local, and mild systemic reactions were not statistically different between YF-vaccine-exposed and -unexposed subjects. In the DoD, there was an increased risk for outpatient allergic events in the period following vaccination with YF and other vaccines rate ratios [RR 3.85, 95% confidence interval (CI) 3.35-4.41] but with no increased risk for inpatient allergic reactions. In both cohorts, inpatient ICD-9 codes for visceral events were significantly less common following vaccination; inpatient codes for neurologic events were less common in the VSD YF-vaccine-exposed adult cohort, but did not differ between exposed and unexposed periods in the DoD. In the DoD, one fatal case of YF-vaccine-associated viscerotropic disease (YF-vaccine-AVD) was detected. The estimated death rate was 0.89 for 1,000,000 YF vaccine doses (95% CI 0.12-6.31/1,000,000 doses). No YF vaccine-associated deaths occurred in the VSD. CONCLUSIONS: In these closed cohorts we did not detect increased risk for visceral or neurologic events following YF vaccination. The death rate following YF vaccine was consistent with previous reports. These data support current recommendations for use of YF vaccine in young healthy individuals. These data are inadequate to judge safety of YF vaccines in elderly patients.

Guillain-Barré Syndrome, Influenza Vaccination, and Antecedent Respiratory and Gastrointestinal Infections: A Case-Centered Analysis in the Vaccine Safety Datalink, 2009-2011.

BACKGROUND: Guillain-Barré Syndrome (GBS) can be triggered by gastrointestinal or respiratory infections, including influenza. During the 2009 influenza A (H1N1) pandemic in the United States, monovalent inactivated influenza vaccine (MIV) availability coincided with high rates of wildtype influenza infections. Several prior studies suggested an elevated GBS risk following MIV, but adjustment for antecedent infection was limited. METHODS: We identified patients enrolled in health plans participating in the Vaccine Safety Datalink and diagnosed with GBS from July 2009 through June 2011. Medical records of GBS cases with 2009-10 MIV, 2010-11 trivalent inactivated influenza vaccine (TIV), and/or a medically-attended respiratory or gastrointestinal infection in the 1 through 141 days prior to GBS diagnosis were reviewed and classified according to Brighton Collaboration criteria for diagnostic certainty. Using a case-centered design, logistic regression models adjusted for patient-level time-varying sources of confounding, including seasonal vaccinations and infections in GBS cases and population-level controls. RESULTS: Eighteen confirmed GBS cases received vaccination in the 6 weeks preceding onset, among 1.27 million 2009-10 MIV recipients and 2.80 million 2010-11 TIV recipients. Forty-four confirmed GBS cases had infection in the 6 weeks preceding onset, among 3.77 million patients diagnosed with medically-attended infection. The observed-versus-expected odds that 2009-10 MIV/2010-11 TIV was received in the 6 weeks preceding GBS onset was odds ratio = 1.54, 95% confidence interval (CI), 0.59-3.99; risk difference = 0.93 per million doses, 95% CI, -0.71-5.16. The association between GBS and medically-attended infection was: odds ratio = 7.73, 95% CI, 3.60-16.61; risk difference = 11.62 per million infected patients, 95% CI, 4.49-26.94. These findings were consistent in sensitivity analyses using alternative infection definitions and risk intervals for prior vaccination shorter than 6 weeks. CONCLUSIONS: After adjusting for antecedent infections, we found no evidence for an elevated GBS risk following 2009-10 MIV/2010-11 TIV influenza vaccines. However, the association between GBS and antecedent infection was strongly elevated.

Clinical practice guideline for the diagnosis and management of acute bacterial sinusitis in children aged 1 to 18 years.

OBJECTIVE: To update the American Academy of Pediatrics clinical practice guideline regarding the diagnosis and management of acute bacterial sinusitis in children and adolescents. METHODS: Analysis of the medical literature published since the last version of the guideline (2001). RESULTS: The diagnosis of acute bacterial sinusitis is made when a child with an acute upper respiratory tract infection (URI) presents with (1) persistent illness (nasal discharge [of any quality] or daytime cough or both lasting more than 10 days without improvement), (2) a worsening course (worsening or new onset of nasal discharge, daytime cough, or fever after initial improvement), or (3) severe onset (concurrent fever[temperature ≥39°C/102.2°F] and purulent nasal discharge for at least 3 consecutive days). Clinicians should not obtain imaging studies of any kind to distinguish acute bacterial sinusitis from viral URI, because they do not contribute to the diagnosis; however, a contrast-enhanced computed tomography scan of the paranasal sinuses should be obtained whenever a child is suspected of having orbital or central nervous system complications. The clinician should prescribe antibiotic therapy for acute bacterial sinusitis in children with severe onset or worsening course. The clinician should either prescribe antibiotic therapy or offer additional observation for 3 days to children with persistent illness. Amoxicillin with or without clavulanate is the firstline treatment of acute bacterial sinusitis. Clinicians should reassess initial management if there is either a caregiver report of worsening(progression of initial signs/symptoms or appearance of new signs/symptoms) or failure to improve within 72 hours of initial management.If the diagnosis of acute bacterial sinusitis is confirmed in a child with worsening symptoms or failure to improve, then clinicians may change the antibiotic therapy for the child initially managed with antibiotic or initiate antibiotic treatment of the child initially managed with observation. CONCLUSIONS: Changes in this revision include the addition of a clinical presentation designated as "worsening course," an option to treat immediately or observe children with persistent symptoms for 3 days before treating, and a review of evidence indicating that imaging is not necessary in children with uncomplicated acute bacterial sinusitis.

Postlicensure surveillance for pre-specified adverse events following the 13-valent pneumococcal conjugate vaccine in children.

Although no increased risk was detected for serious adverse events in the prelicensure trials for the 13-valent pneumococcal vaccine, Prevnar 13(®) (PCV13), continued monitoring of rare but serious adverse events is necessary. A surveillance system using cohort study design was set up to monitor safety of PCV13 immediately after it was included in the childhood immunization program in the United States. The exposed population included children of 1 month to 2 years old who received PCV13 from April, 2010 to January, 2012 from the eight managed care organizations participating in the Vaccine Safety Datalink Project in the United States. The historical unexposed population was children of the same age who received the 7-valent pneumococcal conjugate vaccine Prevnar 7(®) (PCV7) in 2007 (or 2005 depending on the outcome of interest) to 2009. The risk of pre-specified adverse events in the risk window following PCV13 was repeatedly compared to that in the historical comparison group. The number of doses included in the study was 599,229. No increased risk was found for febrile seizures, urticaria or angioneurotic edema, asthma, thrombocytopenia, or anaphylaxis. An increased risk for encephalopathy was not confirmed following the medical record review. The relative risk for Kawasaki disease in 0-28 days following vaccination was 1.94 (95% confidence interval: 0.79-4.86), comparing PCV13 to PCV7. Comparing to PCV7 vaccine, we identified no significant increased risk of pre-specified adverse events in the Vaccine Safety Datalink study cohort. The possible association between PCV13 and Kawasaki disease may deserve further investigation.

Digital images taken with a mobile phone can assist in the triage of neurosurgical patients to a level 1 trauma centre.

We investigated whether head CT images captured using a mobile phone would be of sufficient quality for neurosurgeons at a level 1 trauma centre to make decisions about whether to transfer patients from referring hospitals. All patients who had been transferred from outside facilities with reported intracranial pathology during 2008 were identified. Two emergency medicine physicians selected 1-3 images from the hospital archive that best represented the pathology described by the radiologist and the medical record. The images were photographed in a darkened room using a smart phone. The mobile phone images and clinical history were reviewed by two neurosurgeons independently. The neurosurgeons rated the adequacy and quality of the images, and indicated whether the images would have changed their transfer decision. Based on clinical data alone, neurosurgeon A would have transferred 64 (73%) patients and neurosurgeon B 39 (44%). After images were provided, A would have transferred 67 (76%) and B would have transferred 49 (56%). The availability of the images significantly altered the transfer decision by A in 25 cases (28%) (P = 0.024) and by B in 28 cases (32%) (P < 0.001). The level of agreement between the two neurosurgeons significantly increased from 53% (kappa = 0.11) to 75% (kappa = 0.47) (P < 0.001). Mobile-phone images of CT scans appear to provide adequate images for triaging patients and helping with transfer decisions of neurosurgical cases.

Vaccination site and risk of local reactions in children 1 through 6 years of age.

OBJECTIVE: Our objective was to assess whether the occurrence of medically attended local reactions to intramuscularly administered vaccines varies by injection site (arm versus thigh) in children 1 to 6 years of age. METHODS: This is a retrospective cohort study of children in the Vaccine Safety Datalink population from 2002 to 2009. Site of injection and the outcome of medically attended local reactions were identified from administrative data. RESULTS: The study cohort of 1.4 million children received 6.0 million intramuscular (IM) vaccines during the study period. The primary analyses evaluated the IM vaccines most commonly administered alone, which included inactivated influenza, hepatitis A, and diphtheria-tetanus-acellular pertussis (DTaP) vaccines. For inactivated influenza and hepatitis A vaccines, local reactions were relatively uncommon, and there was no difference in risk of these events with arm versus thigh injections. The rate of local reactions after DTaP vaccines was higher, and vaccination in the arm was associated with a significantly greater risk of this outcome compared with vaccination in the thigh, both for children 12 to 35 months (relative risk: 1.88 [95% confidence interval: 1.34-2.65]) and 3 to 6 years of age (relative risk: 1.41 [95% confidence interval: 0.84-2.34]), although this difference was not statistically significant in the older age group. CONCLUSIONS: Injection in the thigh is associated with a significantly lower risk of a medically attended local reaction to a DTaP vaccination among children 12 to 35 months of age, supporting current recommendations to administer IM vaccinations in the thigh for children younger than 3 years of age.

Safety of a tetanus-diphtheria-acellular pertussis vaccine when used off-label in an elderly population.

BACKGROUND: Published data on the safety of tetanus-diphtheria-acellular pertussis vaccine (Tdap) in persons aged ≥65 years are limited. This study aims to examine a large cohort of Tdap users ≥65 years for evidence of increased risk of adverse events following vaccination. METHODS: A matched cohort study design and a self-controlled case series (SCCS) design were used. The study population was adults aged ≥65 years who received the Tdap or tetanus and diphtheria (Td) vaccine during 1 January 2006-31 December 2010 at 7 health maintenance organizations in the United States. Seven major groups of prespecified events were identified electronically by diagnostic codes. RESULTS: The study included 119 573 Tdap vaccinees and the same number of Td vaccinees. The results indicated that the risk of the prespecified events following Tdap was comparable to that following Td vaccination in this elderly population. There was a small increased rate of codes suggesting medically attended inflammatory or allergic events in 1-6 days following Tdap in the SCCS analysis (incidence rate ratio, 1.59 [95% confidence interval, 1.40-1.81]). CONCLUSION: Although there is a small increased risk of medically attended inflammatory or allergic events in 1-6 days following Tdap compared to other time periods, it is no more common than that following Td. This study provides empirical safety data suggesting that immunizing adults aged ≥65 years with Tdap to reduce the risk of pertussis in the elderly and their contacts should not have untoward safety consequences.

Safety of zoster vaccine in adults from a large managed-care cohort: a Vaccine Safety Datalink study.

OBJECTIVES: The aim of this study was to examine a large cohort of adults who received the zoster vaccine for evidence of an increased risk of prespecified adverse events requiring medical attention. DESIGN: Two self-comparison approaches, including a case-centred approach and a self-controlled case series (SCCS) analysis were used. SETTING: Eight managed-care organizations participating in the Vaccine Safety Datalink project in the United States. SUBJECTS: A total of 193 083 adults aged 50 and older receiving a zoster vaccine from 1 January 2007 to 31 December 2008 were included. MAIN OUTCOME MEASURES: Prespecified adverse events were identified by aggregated International Classification of Diseases, Ninth Revision (ICD-9) codes in automated health plan datasets. RESULTS: The risk of allergic reaction was significantly increased within 1-7 days of vaccination [relative risk = 2.13, 95% confidence interval (CI): 1.87-2.40 by case-centred method and relative rate = 2.32, 95% CI: 1.85-2.91 by SCCS]. No increased risk was found for the following adverse event groupings: cerebrovascular events; cardiovascular events; meningitis; encephalitis; and encephalopathy; and Ramsay-Hunt syndrome and Bell's palsy. CONCLUSIONS: The results of this study support the findings from the prelicensure clinical trials, providing reassurance that the zoster vaccine is generally safe and well-tolerated with a small increased risk of allergic reactions in 1-7 days after vaccination.

Efficacy and tolerability of once-weekly rosuvastatin in patients with previous statin intolerance.

BACKGROUND: Many patients who could benefit from hydroxymethylglutaryl coenzyme-A reductase inhibitors (statins) are unable to take statins because of myalgias while taking previous statin therapy. OBJECTIVE: The primary objective was to assess the efficacy and tolerability of once-weekly rosuvastatin in patients with documented myalgias on statins who were not currently taking a statin and not at low-density lipoprotein (LDL) goal. METHODS: In this randomized, double-blind, placebo-controlled crossover study we enrolled a total of 17 Clement J. Zablocki Veterans Affairs (VA) primary care patients with a diagnosis of hyperlipidemia and a history of myalgias on statin therapy who were not currently on a statin and not at LDL goal. Two 8-week treatment phases consisted of rosuvastatin 5 mg once-weekly or matching placebo, with a dose titration to 10 mg once-weekly if not at LDL goal at week 4. The primary efficacy outcome was the difference in the mean percentage change in LDL from baseline between rosuvastatin and placebo. RESULTS: A significant difference in the mean percentage change in LDL from baseline for rosuvastatin vs. placebo was identified (12.2% reduction vs. 0.4% reduction, respectively; P = .002). Two of the 17 patients (11.8%) in the placebo treatment phase and three of the 15 patients (20%) in the rosuvastatin treatment phase experienced myalgias requiring cessation of therapy. In addition, three patients (20%) were able to attain LDL goal on rosuvastatin compared with zero patients (0%) on placebo. CONCLUSION: Once-weekly low-dose rosuvastatin is an effective and well-tolerated lipid-lowering therapy option for patients not at LDL goal and previously unable to tolerate statins because of a history of myalgias.

Paralytic syndromes in children: epidemiology and relationship to vaccination.

Acute flaccid paralysis is a standard outcome for detection of poliomyelitis globally and an ongoing potential vaccine-associated adverse event concern for polio, influenza, and meningococcal vaccines. No systematic population-based data on the epidemiologic and clinical features of this condition, or its potential association with immunization, have been reported from the United States. The present retrospective cohort study of acute flaccid paralysis in the Southern and Northern California Kaiser Permanente Health Care Plans was conducted using computerized diagnosis data and medical record review of potential cases among children aged 1 month to <15 years and diagnosed from January 1, 1992 through December 31, 1998. In all, 3297 potential cases were identified; of these, 2682 cases (81%) did not meet the case definition, and of the remaining 615 cases, 245 (7% of the total) were included. The incidence of disease was 1.4 per 100,000 children/year (95% confidence interval = 1.2-1.6); predicting approximately 844 children/year in the United States. Disease incidence did not vary with season or sex, varied inversely with age, and declined 28% during the study period. No cases of vaccine-associated acute flaccid paralysis were identified. In nonendemic countries, ongoing acute flaccid paralysis surveillance is often conducted, because of the risk of poliovirus importation, but this practice may be difficult to justify, given low disease incidence and breadth of clinical presentation.

Risk factors of herpes zoster among children immunized with varicella vaccine: results from a nested case-control study.

BACKGROUND: Previous studies of varicella-zoster virus reactivation in children have provided little information on potential risk factors. The aim of this study was to investigate the effects of race, chronic medical conditions and treatments, and recent vaccination, on the risk of herpes zoster (HZ) in children vaccinated with one dose of varicella vaccine. METHODS: Case subjects were identified from a cohort of subjects who were members of the Southern California Kaiser Permanente Health Plan and received primary immunization with a single-antigen live varicella vaccine at age < or = 12 years from 2002 to 2008. Control subjects free of HZ during the study period were matched at a 5:1 ratio to each case subject on date of birth and sex. Race information was obtained from membership files, health records, and phone interview. Immunization history, medical history, and health care utilization were identified from Southern California Kaiser Permanente Health Plan electronic records. RESULTS: During this time, 122 children were diagnosed with HZ. With adjustment for the number of hospitalizations, outpatient visits, and length of time between vaccination with varicella vaccine and the onset of HZ, Black children were at lower risk of developing HZ than were White (OR=0.41, 95% CI=0.17-0.98) and Asian children (OR=0.30, 95% CI=0.11-0.84). CONCLUSIONS: These data suggest that the racial differences in the risk of developing HZ seen in adults are manifest in children as well. As children are not subject to the majority of factors hypothesized to underlie HZ in adults and as this study was conducted in a setting which affords equal access to health care, it is possible that genetic variation may explain some portion of varicella-zoster virus reactivation.

Intrauterine growth patterns in fetal gastroschisis.

The objective of this study was to evaluate patterns of intrauterine growth in fetal gastroschisis. This was a retrospective review of prenatally diagnosed cases of fetal gastroschisis delivered at the University of North Carolina Hospital from January 2000 to January 2007. Fetal growth (biparietal diameter, head circumference, abdominal circumference, femur length, and estimated fetal weight) and amniotic fluid volume were evaluated by gestational age. Gastroschisis was diagnosed in 83 pregnancies; outcomes were available in 71 fetuses. The mean gestational age at diagnosis was 17 weeks and 1 day. The mean gestational age at delivery was 35 weeks and 4 days. Mean birth weight was 2306 g. As early as the second trimester, all morphometric measures demonstrated impaired in utero growth, with growth curves shifted to the right of the 50th percentile when compared with a standard population. Estimated fetal weight below the 10th percentile was suspected in 23% of pregnancies, and birth weight at less than the 10th percentile occurred in 47% of neonates. Amniotic fluid volumes remained stable throughout gestation. Fetuses with gastroschisis display impaired intrauterine growth, which is noted in the midsecond trimester of pregnancy and does not appear to progress throughout gestation.

Evaluation of vaccine coverage for low birth weight infants during the first year of life in a large managed care population.

OBJECTIVE: There are few recent population-based assessments of vaccine coverage in premature infants available. This study assesses and compares age- and dose-specific immunization coverage in children of different birth weight categories during the first year of life. METHODS: We performed a retrospective cohort analysis of computerized vaccination data from a large managed care organization in southern California. The participants were children born between January 1, 1997, and December 31, 2002, and continuously enrolled from birth to at least 12 months of age in the Southern California Kaiser Permanente health plan. We measured age-specific up-to-date and age-appropriate immunization rates according to birth weight (extremely low birth weight: <1000 g; very low birth weight: 1000-1499 g; low birth weight: 1500-2499 g; normal birth weight: >/=2500 g) for 4 vaccines (hepatitis B, diphtheria and tetanus toxoids with pertussis, Haemophilus influenzae type b, and poliovirus) through the first year of life. RESULTS: We identified 127 833 infants born during the study period and continuously enrolled through the first year of life; 120 048 were normal birth weight infants; 6491 were low birth weight infants; 788 were very low birth weight infants; and 506 were extremely low birth weight infants. Vaccine-specific age-appropriate immunization rates were 3% to 15% lower for low birth weight infants and 17% to 33% lower for extremely low birth weight infants compared with the rates for normal birth weight infants in the first 6 months of life. Extremely low birth weight infants had the lowest age-specific up-to-date immunization levels (5%-31% lower) compared with normal birth weight infants at each age assessed. By 12 months, extremely low birth weight infants still had significantly lower up-to-date levels (87%) compared with very low birth weight, low birth weight, and normal birth weight infants (91%-92%). CONCLUSIONS: Despite recommendations that lower birth weight infants be vaccinated as the same chronological age as normal birth weight infants, extremely low birth weight and very low birth weight infants are immunized at significantly lower rates relative to low birth weight and normal birth weight infants at 2, 4, and 6 months of age. However, by 12 months of age this finding persists only in extremely low birth weight infants.

Varicella vaccination and ischemic stroke in children: is there an association?

BACKGROUND: Ischemic stroke is a known complication of varicella disease. Although there have been case reports of ischemic stroke after varicella vaccination, the existence and magnitude of any vaccine-associated risk has not been determined. OBJECTIVE. The purpose of this work was to determine whether varicella vaccination is associated with an increased risk of ischemic stroke and encephalitis in children within 12 months after vaccination. PATIENTS AND METHODS: We conducted a retrospective cohort study based on computerized data from children 11 months through 17 years old enrolled for > or =12 months in the Vaccine Safety DataLink from 1991 through 2004. International Classification of Disease codes identified cases of ischemic stroke (433-436, 437.1, 437.4, 437.6, 437.8-437.9) and encephalitis (052.0, 323.5, 323.8-9). Cox regression was used to model the risk in the 12 months after vaccination relative to all other person-time. Covariates included calendar time, gender, and stroke risk factors (eg, sickle cell disease). RESULTS: Varicella vaccine was administered to 35.3% of the 3.2 million children in the cohort. There were 203 new inpatient ischemic stroke diagnoses, including 8 that occurred within 12 months after vaccination; there was no temporal clustering. The adjusted stroke hazard ratio was not elevated during any of the time periods in the 12 months after vaccination. Stroke was strongly associated with known risk factors such as sickle cell disease and cardiac disease. None of the 243 encephalitis cases occurred during the first 30 days after vaccination, and there was no association between encephalitis and varicella vaccination at any time in the 12 months after vaccination. CONCLUSION: Our retrospective cohort study of >3 million children found no association between varicella vaccine and ischemic stroke.