73 research outputs found
Measurement of inclusive D*+- and associated dijet cross sections in photoproduction at HERA
Inclusive photoproduction of D*+- mesons has been measured for photon-proton
centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality
Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of
37 pb^-1. Total and differential cross sections as functions of the D*
transverse momentum and pseudorapidity are presented in restricted kinematical
regions and the data are compared with next-to-leading order (NLO) perturbative
QCD calculations using the "massive charm" and "massless charm" schemes. The
measured cross sections are generally above the NLO calculations, in particular
in the forward (proton) direction. The large data sample also allows the study
of dijet production associated with charm. A significant resolved as well as a
direct photon component contribute to the cross section. Leading order QCD
Monte Carlo calculations indicate that the resolved contribution arises from a
significant charm component in the photon. A massive charm NLO parton level
calculation yields lower cross sections compared to the measured results in a
kinematic region where the resolved photon contribution is significant.Comment: 32 pages including 6 figure
Measurement of the Diffractive Cross Section in Deep Inelastic Scattering using ZEUS 1994 Data
The DIS diffractive cross section, , has been measured in the mass range GeV for c.m. energies GeV and photon virtualities to 140 GeV. For fixed and , the diffractive cross section rises rapidly with , with corresponding to a -averaged pomeron trajectory of \bar{\alphapom} = 1.127 \pm 0.009 (stat)^{+0.039}_{-0.012} (syst) which is larger than \bar{\alphapom} observed in hadron-hadron scattering. The dependence of the diffractive cross section is found to be the same as that of the total cross section for scattering of virtual photons on protons. The data are consistent with the assumption that the diffractive structure function factorizes according to \xpom F^{D(3)}_2 (\xpom,\beta,Q^2) = (x_0/ \xpom)^n F^{D(2)}_2(\beta,Q^2). They are also consistent with QCD based models which incorporate factorization breaking. The rise of \xpom F^{D(3)}_2 with decreasing \xpom and the weak dependence of on suggest a substantial contribution from partonic interactions
Exclusive Electroproduction of and Mesons at HERA
Exclusive production of and mesons in e^+ p collisions has
been studied with the ZEUS detector in the kinematic range for the data and for the data. Cross sections for exclusive and
production have been measured as a function of and . The
spin-density matrix elements and have
been determined for exclusive production as well as and
for exclusive production.
The results are discussed in the context of theoretical models invoking soft
and hard phenomena.Comment: 57 pages including 21 figures, minor modifications to Figs. 19-21,
these figures supercede those of Eur. Phys. J. C6 (1999) 603-62
Projected risks and health benefits of vaccination against herpes zoster and related complications in US adults
The Advisory Committee on Immunization Practices (ACIP) recommends recombinant zoster vaccine (RZV) to prevent against herpes zoster (HZ) and related complications in immunocompetent adults ≥50 y and immunocompromised adults ≥19 y. In 2019, a statistical safety signal for Guillain-Barré syndrome (GBS) following RZV was identified using data from the Vaccine Safety Datalink (VSD). Subsequently, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and collaborators undertook additional analyses using Centers for Medicare & Medicaid Services (CMS) Medicare data to further investigate the potential risk of GBS following RZV. Concurrently, epidemiologic data suggested a potentially elevated risk of GBS following HZ in U.S. adults. Using data from these sources and a published simulation model, this study evaluated the health benefits and risks associated with vaccinating immunocompetent adults ≥50 y with RZV compared to no vaccination. In the base case analysis, RZV vaccination averted 43,000–63,000 cases of HZ, including GBS complications, per million vaccinated per 10-y age cohort compared to 3–6 additional cases of GBS projected following RZV per million vaccinated in the same population. This analysis highlights the projected health benefits of RZV vaccination compared to the relatively low potential risk of GBS following RZV
TRIVAC decision-support model for evaluating the cost-effectiveness of Haemophilus influenzae type b, pneumococcal and rotavirus vaccination.
The TRIVAC decision support model has been used widely in Latin America and other regions to help national teams evaluate the cost-effectiveness of Haemophilus influenzae type b (Hib) vaccine, pneumococcal conjugate vaccine (PCV) and rotavirus vaccine (RV). We describe the structure and functioning of this model, and identify the parameters with the greatest influence on the results. The TRIVAC model is a spreadsheet software program that calculates incremental cost-effectiveness ratios (ICERs) and other indicators for three childhood vaccines (Hib, PCV and RV) utilising parameters such as demography, disease burden, vaccine costs, vaccine coverage, vaccine efficacy, health service utilisation and costs. There is a good deal of uncertainty about the local values of many of the parameters that have most influence on the cost-effectiveness of these new vaccines. Cost-effectiveness models can be used to explore the implications of different values of these parameters. However, for such models to be seen as relevant and helpful by decision-makers, they need to be transparent, flexible, easy to use, and embedded in a process which is owned and led by national teams. In this paper the key drivers of cost-effectiveness in the model are identified by one-way sensitivity analyses, run for each vaccine in 147 countries. The data used are mainly from standard international sources and the published literature. The primary indicator was the discounted cost per Disability Adjusted Life-Year (DALY) averted, from a government perspective, over a 20-year period (2013-2032). For all three vaccines, the ICER was most sensitive to changes in relative coverage (the coverage of the children who would have become diseased or, more importantly, died if the population had not been vaccinated, as a % of overall national coverage) and the herd effect multiplier. Other influential parameters for all three vaccines were: the incidence and case fatality of disease, the baseline trend in disease mortality in the absence of vaccination, vaccine efficacy, vaccine price and the % decline in vaccine price per year. Important vaccine-specific parameters included the cost of Hib meningitis sequelae, PCV serotype coverage and the rotavirus gastro-enteritis (RVGE) admission rate. While vaccine efficacy, herd effects, disease mortality and vaccine price are commonly cited as important drivers of cost-effectiveness, this analysis highlights the potentially important influence of relative coverage, a parameter rarely considered in models of vaccine impact and cost-effectiveness
Complete and on-time routine childhood immunisation: determinants and association with severe morbidity in urban informal settlements, Nairobi, Kenya
Background: Completion of the full series of childhood vaccines on-time is crucial to ensuring greater protection against vaccine-preventable diseases. Aim: To examine determinants of complete and on-time vaccination and evaluate the relationship between vaccination patterns and severe morbidity outcomes. Subjects and methods: Vaccination information from infants in Nairobi Urban Health and Demographic Surveillance System was used to evaluate full and on-time vaccination coverage of routine immunisation. Logistic regression was used to identify determinants of full and on-time vaccination coverage. Cox regression model was used to evaluate the relationship between vaccination status and subsequent severe morbidity. A shared frailty cox model was fitted to account for the heterogeneity in hospitalisation episodes. Results: Maternal age, post-natal care, parity, ethnicity, and residence place were identified as determinants of vaccination completion. Institutional deliveries and residence place were identified as the determinants of on-time vaccination. A significant 58% (confidence interval [CI]: 15–79%) (p = .017) lower mortality was observed among fully immunised children compared with not fully immunised. Lower mortality was observed among on-time immunised children, 64% (CI: 20–84%) compared to those with delays. Conclusions: Improving vaccination timeliness and completion schedule is critical for protection against vaccine preventable diseases and may potentially provide protection beyond these targets
Severe Acute Respiratory Infection (SARI) sentinel surveillance in the country of Georgia, 2015-2017.
BACKGROUND:Severe Acute Respiratory Infection (SARI) causes substantial mortality and morbidity worldwide. The country of Georgia conducts sentinel surveillance to monitor SARI activity and changes in its infectious etiology. This study characterizes the epidemiology of SARI in Georgia over the 2015/16 and 2016/17 influenza seasons, compares clinical presentations by etiology, and estimates influenza vaccine effectiveness using a test-negative design. METHODS:SARI cases were selected through alternate day systematic sampling between September 2015 and March 2017 at five sentinel surveillance inpatient sites. Nasopharyngeal swabs were tested for respiratory viruses and Mycoplasma pneumoniae using a multiplex diagnostic system. We present SARI case frequencies by demographic characteristics, co-morbidities, and clinical presentation, and used logistic regression to estimate influenza A vaccine effectiveness. RESULTS:1,624 patients with SARI were identified. More cases occurred in February (28.7%; 466/1624) than other months. Influenza was the dominant pathogen in December-February, respiratory syncytial virus in March-May, and rhinovirus in June-November. Serious clinical symptoms including breathing difficulties, ICU hospitalization, and artificial ventilation were common among influenza A and human metapneumovirus cases. For influenza A/H3, a protective association between vaccination and disease status was observed when cases with unknown vaccination status were combined with those who were unvaccinated (OR: 0.53, 95% CI: 0.30, 0.97). CONCLUSIONS:Multi-pathogen diagnostic testing through Georgia's sentinel surveillance provides useful information on etiology, seasonality, and demographic associations. Influenza A and B were associated with more severe outcomes, although the majority of the population studied was unvaccinated. Findings from sentinel surveillance can assist in prevention planning
Monthly distribution of respiratory pathogens in a Severe Acute Respiratory Infection surveillance system in the country of Georgia, 2015–2017.
<p>Monthly distribution of respiratory pathogens in a Severe Acute Respiratory Infection surveillance system in the country of Georgia, 2015–2017.</p
Demographic and clinical characteristics of cases within a Severe Acute Respiratory Infection surveillance system in the country of Georgia, 2015–2017.
<p>Demographic and clinical characteristics of cases within a Severe Acute Respiratory Infection surveillance system in the country of Georgia, 2015–2017.</p
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