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1AbstractBackgroundRespiratory syncytial virus (RSV) is associated with acute respiratory infection. We sought to identify RSV variants associated with prolonged infection.MethodsAmong healthy term infants we identified those with prolonged RSV infection and conducted 1) a human GWAS to test the dependence of infection risk on host genotype, 2) a viral GWAS for association with prolonged RSV infection using RSV whole-genome sequencing, 3) an analysis of all viral public sequences, 4) an assessment of immunological responses, and 5) a summary of all major functional data. Analyses were adjusted for viral/human population structure and host factors associated with infection risk.ResultsWe identified p.E123K/D and p.P218T/S/L in G protein that were associated with prolonged infection (Padj= 0.01). We found no evidence of host genetic risk for infection. The RSV variant positions approximate sequences that could bind a putative viral receptor, heparan sulfate.ConclusionsUsing analysis of both viral and host genetics we identified a novel RSV variant associated with prolonged infection in healthy infants and no evidence supporting host genetic susceptibility to infection. As the capacity of RSV for chronicity and its viral reservoir are not defined, these findings are important for understanding the impact of RSV on chronic disease and endemicity.Key pointsUsing a comprehensive computational analysis of viral and host genetics we identified a novel RSV variant associated with prolonged infection and no evidence supporting host genetic infection susceptibility, findings important to understanding RSV contribution to chronic disease and viral endemicity.SummaryA comprehensive computational statistical analysis of both host and viral genetics provided compelling evidence for RSV viral persistence in healthy human infants, a finding of significant importance to understanding the impact of RSV on chronic disease and viral endemicity.

Background The potential for prenatal antibiotic exposure to influence asthma risk is not clear. We aimed to determine the effect of timing, dose, and spectrum of prenatal antibiotic exposure on the risk of childhood asthma. Methods We conducted a population-based cohort study of 84 214 mother–child dyads to examine the association of prenatal antibiotic exposure and childhood asthma using multivariable logistic regression models. Results Sixty-four percent of pregnant women received antibiotics. Prenatal antibiotic exposure was associated dose-dependently with increased odds of childhood asthma (adjusted odds ratio [aOR] for interquartile increase of 2 courses [interquartile range, 0–2], 1.26 [95% confidence interval {CI}, 1.20–1.33]). Among children exposed to at least 1 course in utero, the effect of timing at the first course was moderated by total maternal courses. Among pregnant women receiving a single antibiotic course, timing of exposure had no effect on childhood asthma risk. Among women receiving > 1 course, early exposure of the first course was associated with greater childhood asthma risk. Compared to narrow spectrum–only antibiotic use, broad spectrum–only antibiotic exposure was associated with increased odds of asthma (aOR, 1.14 [95% CI, 1.05–1.24]). There were effect modifications (P Conclusions Increased cumulative dose, early pregnancy first course, and broad-spectrum antibiotic exposure were associated with childhood asthma risk. Our study provides important evidence supporting judicious prenatal antibiotic use, particularly timing of use and choice of antibiotics, in preventing subsequent childhood asthma.

We sought to determine the real-world effectiveness of respiratory syncytial virus (RSV) immunoprophylaxis in a population-based cohort to inform policy. The study population included infants born during 1996–2008 and enrolled in the Kaiser Permanente Northern California integrated health-care delivery system. During the RSV season (November–March), the date of RSV immunoprophylaxis administration and the following 30 days were defined as RSV immunoprophylaxis protected period(s), and all other days were defined as unprotected period(s). Numbers of bronchiolitis hospitalizations were determined using International Classification of Diseases, Ninth Revision, codes during RSV season. We used a proportional hazards model to estimate risk of bronchiolitis hospitalization when comparing infants’ protected period(s) with unprotected period(s). Infants who had ever received RSV immunoprophylaxis had a 32% decreased risk of bronchiolitis hospitalization (adjusted hazard ratio = 0.68, 95% confidence interval: 0.46, 1.00) when protected periods were compared with unprotected periods. Infants with chronic lung disease (CLD) had a 52% decreased risk of bronchiolitis hospitalization (adjusted hazard ratio = 0.48, 95% confidence interval: 0.25, 0.94) when protected periods were compared with unprotected periods. Under the new 2014 American Academy of Pediatrics (AAP) guidelines, 48% of infants eligible for RSV immunoprophylaxis on the basis of AAP guidelines in place at birth would no longer be eligible, but nearly all infants with CLD would remain eligible. RSV immunoprophylaxis is effective in decreasing hospitalization. This association is greatest for infants with CLD, a group still recommended for receipt of RSV immunoprophylaxis under the new AAP guidelines.

Immunoprophylaxis is the only pharmaceutical intervention for mitigating respiratory syncytial virus (RSV) infection. Patient level data on adherence to American Academy of Pediatrics (AAP) immunoprophylaxis recommendations are limited. This study characterizes adherence to AAP guidelines in privately insured and Medicaid populations.We performed a retrospective birth cohort study of 211 174 privately insured children in Northern California; and 458 837 publicly insured children in Tennessee born between January 1, 1996 and December 31, 2008. Adherence to the AAP guideline was defined for eligible infants as the number of doses of RSV immunoprophylaxis administered over the number recommended for 4 mutually exclusive eligibility groups: chronic lung disease, prematurity29 weeks, prematurity32 weeks, and other eligibility.We identified 3456 California (Kaiser Permanente Northern California [KPNC]) and 12 251 Tennessee (Tennessee Medicaid [TennCare]) infants meeting AAP eligibility criteria. Immunoprophylaxis administration increased over the study period, from 15% for all eligible groups in 1998 to 54% in 2007. Adherence was highest among babies with chronic lung disease (KPNC 67% and TennCare 55%). Nonadherence (0% adherence) was greatest among infants of African American mothers (adjusted odds ratio [AOR] = 1.32; 95% confidence interval [CI] = .98-1.78); those with mothers with less than a high school education (AOR = 1.58; CI = 1.09-2.30) in KPNC; and in infants of Hispanic mothers in TennCare (AOR = 1.65; CI = 1.24-2.20). In KPNC, 0.11% of ineligible term infants and 5% of ineligible premature infants received immunoprophylaxis; the corresponding proportions in TennCare were 1% and 11%.Overall adherence with AAP guidelines has increased over time. Considerable overuse and underuse of immunoprophylaxis are evident with identifiable risk groups to target for improvement.

BACKGROUND Polymorphisms in CYP2B6 affect the steady-state plasma concentrations of nevirapine and efavirenz. In many resource-limited countries, a single dose of nevirapine has been widely prescribed to pregnant women at delivery, to reduce mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1). We characterized associations between genetic polymorphisms and the pharmacokinetics of single doses of nevirapine and efavirenz. METHODS Plasma drug concentrations were determined over the 13-day period after administration of a 200-mg oral dose of nevirapine to nonpregnant, HIV-negative African Americans. A 600-mg oral dose of efavirenz was subsequently administered, and pharmacokinetic sampling was repeated. Pharmacokinetic parameters were estimated using a noncompartmental approach. Primary analyses involved 2 CYP2B6 polymorphisms (516G --> T and 983T --> C) known to predict increased steady-state plasma nevirapine and efavirenz exposure. Exploratory analyses involved another 51 polymorphisms in CYP2B6, ABCB1, CYP3A4, and CYP3A5. RESULTS On the basis of the composite CYP2B6 516/983 genotype, the 34 participants comprised 10 extensive, 17 intermediate, and 7 slow metabolizer genotypes. The composite CYP2B6 516/983 genotype was significantly associated with plasma drug exposure and clearance for efavirenz but not nevirapine. Exploratory analyses suggested possible associations between additional CYP2B6 polymorphisms and the pharmacokinetics of nevirapine and efavirenz. CONCLUSIONS Selective pressure for drug-resistant HIV-1 after administration of single-dose nevirapine may not differ substantially according to CYP2B6 516/983 genotype. Additional polymorphisms, genes, and populations warrant further study.