Umesh D Parashar

Centers for Disease Control and Prevention, Атланта, Michigan, United States

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Publications (396)2863.34 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To analyze the prevalence of acute asymptomatic group A and C rotavirus (RV-A and RV-C) infection in neonates with cholestasis. Participants were infants <180 days of age with cholestasis (serum direct or conjugated bilirubin >20% of total and ≥2 mg/dL) enrolled in the Childhood Liver Disease Research and Education Network during RV season (December-May). Forty infants with biliary atresia (BA), age 62 ± 29 days (range, 4.7-13 weeks) and 38 infants with cholestasis, age 67 ± 44 days (range, 3-15.8 weeks) were enrolled. At enrollment, RV-A IgM positivity rates did not differ between infants with BA (10%) vs those without (18%) (P = .349). RV-C IgM was positive in 0% of infants with BA vs 3% in those without BA (P = .49). RV-A IgG was lower in infants with BA: 51 ± 39 vs 56 ± 44 enzyme-linked immunoassay unit, P = .045 but this difference may lack biological relevance as maternal RV-A IgG titers were similar between groups. Infant RV-A IgM titers at 2-6 months follow-up increased markedly vs at presentation in both infants with BA (50 ± 30 vs 9 ± 9) and those without (43 ± 18 vs 16 ± 20 enzyme-linked immunoassay unit) (P < .0001), without differences between groups. RV-A infection in the first 6 months of life is common in infants with cholestasis of any cause. RV-A could have different pathogenetic effects by initiating different hepatic immune responses in infants with vs without BA or could lack pathogenetic significance. Copyright © 2014 Elsevier Inc. All rights reserved.
    Journal of Pediatrics 10/2014; 166(1). DOI:10.1016/j.jpeds.2014.09.033 · 3.74 Impact Factor
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    Daniel E Velasquez, Umesh D Parashar, Baoming Jiang
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    ABSTRACT: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
    Infection Genetics and Evolution 10/2014; DOI:10.1016/j.meegid.2014.10.008 · 3.26 Impact Factor
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    ABSTRACT: Background: An estimated 179 million acute gastroenteritis (AGE) illnesses occur annually in the United States. Many AGE outbreaks attributed to norovirus occur in healthcare settings. The role of norovirus in healthcare-related AGE has important implications for the development and implementation of preventive strategies, but the burden has not been well-documented in U.S. acute care facilities. We estimated the incidence of community- and hospital-acquired norovirus AGE at four geographically distinct Veterans Affairs (VA) Medical Centers and their associated outpatient clinics in Atlanta, GA; Bronx, NY; Houston, TX; and Los Angeles, CA. Methods: From November 2011 to October 2012, stool specimens from all patients with AGE for clinician-requested diagnostic testing were stored and shipped to the Centers for Disease Control and Prevention (CDC) for supplemental testing for the presence of norovirus. Outpatient and community- and hospital-acquired inpatient norovirus-associated AGE incidence were calculated using administrative and patient population data from each VA Center. Results: Fifty (4%) of 1,160 stool specimens collected ≤7 days from symptom onset tested positive for norovirus; 6.9% of outpatient (n=203), 6.2% of community-acquired inpatient (n=375), and 2.2% of hospital-acquired inpatient (n=582) samples tested positive for norovirus. Norovirus-positivity followed a seasonal pattern with 33 (66%) of norovirus-positive specimens collected between November 2011 and March 2012. During a one year period, the estimated incidence of community and hospital-acquired norovirus AGE was 200 and 62 cases/ 100,000 patients, respectively. A total of 7 norovirus genotypes were detected of which the majority (74%) was one of the GII.4 variants including GII.4 New Orleans (46%), GII.4 Minerva (14%), and GII.4 Sydney (14%). Five specimens (10%) were GI.6, a typically uncommon genotype that transiently emerged nationwide as a major disease-causing variant during this period. Conclusion: This study demonstrates the incidence of community- and hospital-acquired norovirus AGE among a geographically distributed VA population.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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    ABSTRACT: Background: Concerns exist whether monovalent (RV1) and pentavalent (RV5) rotavirus vaccines provide adequate protection against diverse strains and whether vaccine introduction will lead to selective pressure. Methods: We systematically reviewed vaccine effectiveness (VE) studies and classified strains as (1) homotypic: both G- and P-type antigen of the circulating strain were in the vaccine; (2) partially heterotypic: either the G- or P-type antigen of the circulating strain was in the vaccine; and (3) fully heterotypic: neither G- or P-type antigen of the circulating strain was in the vaccine. Some RV5 studies reported VE against the G- and the P-type component separately and could not be discreetly classified into the three categories. To make complete use of the data, we included these strains in our analysis, classifying them either as (1) single antigen (SA) vaccine-type; or (2) SA nonvaccine-type. We estimated pooled odds ratios using random effect regression models, and tested for differences in strain-specific VE. Strain distribution trends were assessed from surveillance reports. Results: In high income countries, RV1 pooled VE (95% CI) was 94% (80-98), 71% (39-86), and 87% (76-93) against homotypic, partially heterotypic, and fully heterotypic strains, respectively. RV5 VE was 83% (78-87), 82% (70-89), 82% (70-89) and 75% (47-88) against homotypic, SA vaccine-type, partially heterotypic, and SA nonvaccine-type strains, respectively. In middle income countries, RV1 pooled VE was 59% (36-73), 72% (58-81), and 47% (28-61) against homotypic, partially, and fully heterotypic strains, respectively. RV5 VE was 70% (58-78) against SA vaccine-type, 37% (10-56) against partially heterotypic strains and 87% (38-97) against SA nonvaccine-type. We found no evidence of a difference in VE for either vaccine in any setting (all p<0.05) Prevalent strains in RV1 countries were G2P[4] (50%) and G1P[8] (22%), compared with G1P[8] (33%) and G2P[4] (30%) in RV5 countries . Sustained predominance of a single strain was not observed. Conclusion: RV1 and RV5 exert similar effectiveness against homotypic and heterotypic strains. We found no evidence for persistence of specific strains indicating vaccine-induced selective pressure.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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    ABSTRACT: Background The effectiveness of the rotavirus vaccine under conditions of routine use in an African setting with a high prevalence of HIV infection needs to be established. We assessed the vaccine effectiveness of monovalent human rotavirus vaccine in preventing admission to hospital for acute rotavirus diarrhoea, after its introduction at age 6 and 14 weeks into South Africa's national immunisation programme. Methods This case-control study was done at seven hospitals in South Africa between April 19, 2010, and Oct 31, 2012. The hospitals were located in a range of urban, peri-urban, and rural settings, with varying rates of population HIV infection. Cases were children aged from 18 weeks to 23 months who were age-eligible to have received at least one dose of the human rotavirus vaccine (ie, those born after June 14, 2009) admitted to hospital with laboratory-confirmed acute rotavirus diarrhoea, and the primary control group was children admitted to hospital with diarrhoea testing negative for rotavirus. A second control group comprised children admitted to a subset of three of the seven hospitals with respiratory illness. The primary endpoint was adjusted vaccine effectiveness (1 – adjusted odds ratio × 100%) in children aged from 18 weeks to 23 months and was calculated by unconditional logistic regression. This study is registered on the South African National Clinical Trial Register, number DOH-27-0512-3247. Findings Of 540 rotavirus-positive cases, 278 children (52%) received two doses, 126 (23%) one dose, and 136 (25%) no doses of human rotavirus vaccine, compared with 1434 rotavirus-negative controls of whom 856 (60%) received two doses, 334 (23%) one dose, and 244 (17%) no doses. Adjusted vaccine effectiveness using rotavirus-negative controls was 57% (95% CI 40–68) for two doses and 40% (16–57) for one dose; estimates were similar when respiratory controls were used as the control group. Adjusted vaccine effectiveness for two doses was similar between age groups 18 weeks–11 months (54%, 95% CI 32–68) and 12–23 months (61%, 35–77), and was similar in HIV-exposed-uninfected (64%, 95% CI 34–80) and HIV-unexposed-uninfected children (54%, 31–69). Interpretation Human rotavirus vaccine provided sustained protection against admission to hospital for acute rotavirus diarrhoea during the first and second years of life. This finding is encouraging and establishes the public health value of rotavirus vaccine in an African setting, especially as rotavirus vaccines are introduced into an increasing number of African countries. Funding GAVI Alliance (with support from PATH).
    The Lancet Infectious Diseases 10/2014; 14(11). DOI:10.1016/S1473-3099(14)70940-5 · 19.45 Impact Factor
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    ABSTRACT: Group A Rotaviruses (RVA) are double stranded RNA viruses that are a significant cause of acute pediatric gastroenteritis. Beginning in 2006 and 2008, respectively, two vaccines, Rotarix™ and RotaTeq®, have been approved for use in the USA for prevention of RVA disease. The effects of possible vaccine pressure on currently circulating strains in the USA and their genome constellations are still under investigation. In this study we report 33 complete RVA genomes (ORF regions) collected in multiple cities across USA during 2006 – 2009, including 8 collected from children with verified receipt of 3 doses of rotavirus vaccine. The strains included 16 G1P[8], 10 G3P[8], and 7 G9P[8]. All 33 strains had a Wa like backbone with the consensus genotype constellation of G(1/3/9)-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. From maximum likelihood based phylogenetic analyses, we identified 3 to7 allelic constellations grouped mostly by respective G types, suggesting a possible allelic segregation based on the VP7 gene of RVA primarily for the G3 and G9 strains. The vaccine failure strains showed similar grouping for all genes in G9 strains and most genes of G3 strains suggesting that these constellations were necessary to evade vaccine-derived immune protection. Substitutions in the antigenic region of VP7 and VP4 genes were also observed for the vaccine failure strains which could possibly explain how these strains escape vaccine induced immune response. This study helps elucidate how RVA strains are currently evolving in the population post vaccine introduction and supports the need for continued RVA surveillance.
    Infection Genetics and Evolution 10/2014; 28. DOI:10.1016/j.meegid.2014.09.021 · 3.26 Impact Factor
  • Clinical Infectious Diseases 09/2014; 60(1). DOI:10.1093/cid/ciu746 · 9.42 Impact Factor
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    ABSTRACT: We used Truven Health Marketscan claims database (2008-2011) to compare gastroenteritis rates during January-June among households whose child had received rotavirus vaccine with those whose child did not receive vaccine. Statistically significantly lower rates of hospitalization with a rotavirus gastroenteritis or unspecified-gastroenteritis discharge code occurred in vaccinated households among persons 20-29 years and females 20-29 years (2008/09), and males 30-39 years (2009/10). Lower emergency department gastroenteritis rates occurred in vaccinated households among females 20-29 years (2009/2010) and individuals 5-19 years (2010/2011). These data suggest rotavirus vaccination of infants provides indirect protection against moderate-to-severe rotavirus disease in young parents and older siblings.
    The Journal of Infectious Diseases 09/2014; 211(4). DOI:10.1093/infdis/jiu503 · 5.78 Impact Factor
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    ABSTRACT: Comprehensive reviews of pre licensure rotavirus strain prevalence data indicated the global importance of six rotavirus genotypes, G1P[8], G2P[4], G3P[8], G4P[8], G9P[8] and G12P[8]. Since 2006, two vaccines, the monovalent Rotarix (RV1) and the pentavalent RotaTeq (RV5) have been available in over 100 countries worldwide. Of these, 60 countries have already introduced either RV1 or RV5 in their national immunization programs. Post licensure vaccine effectiveness is closely monitored worldwide. This review aimed at describing the global changes in rotavirus strain prevalence over time. The genotype distribution of the nearly 47,000 strains that were characterized during 2007-2012 showed similar picture to that seen in the preceding period. An intriguing finding was the transient predominance of heterotypic strains, mainly in countries using RV1. Unusual and novel antigen combinations continue to emerge, including some causing local outbreaks, even in vaccinated populations. In addition, vaccine strains have been found in both vaccinated infants and their contacts and there is evidence for genetic interaction between vaccine and wild-type strains. In conclusion, the post-vaccine introduction strain prevalence data do not show any consistent pattern indicative of selection pressure resulting from vaccine use, although the increased detection rate of heterotypic G2P[4] strains in some countries following RV1 vaccination is unusual and this issue requires further monitoring.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 09/2014; 28. DOI:10.1016/j.meegid.2014.08.017 · 3.26 Impact Factor
  • The National medical journal of India 09/2014; 27(5):245-8. · 0.91 Impact Factor
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    ABSTRACT: Background Concerns exist about whether monovalent (RV1) and pentavalent (RV5) rotavirus vaccines provide adequate protection against diverse strains and whether vaccine introduction will lead to selective pressure. We aimed to investigate the distribution of rotavirus strains and strain-specific rotavirus vaccine effectiveness after vaccine introduction. Methods We did a systematic review of published work to assess the strain-specific effectiveness of RV1 and RV5 rotavirus vaccines. We classified strains as homotypic, partly heterotypic, and fully heterotypic based on the amount of antigen-matching between strain and vaccine. When studies reported vaccine effectiveness against single antigens (G-type or P-type), we categorised them as either single-antigen vaccine type or single-antigen non-vaccine type. Our primary outcome was strain-specific vaccine effectiveness, comparing effectiveness of homotypic strains with fully or partly heterotypic strains. A secondary outcome was the prevalence of rotavirus strains after vaccine introduction. We estimated pooled odds ratios using random-effect regression models, stratified by country income level and vaccine type, and tested for differences in strain-specific vaccine effectiveness. We assessed strain distribution trends from surveillance reports. Findings In high-income countries, RV1 pooled vaccine effectiveness was 94% (95% CI 80–98) against homotypic strains, 71% (39–86) against partly heterotypic strains, and 87% (76–93) against fully heterotypic strains. In middle-income settings, respective pooled data were 59% (36–73), 72% (58–81), and 47% (28–61). In high-income countries, RV5 vaccine effectiveness was 83% (78–87) against homotypic strains, 82% (70–89) against single-antigen vaccine type strains, 82% (70–89) against partly heterotypic strains, and 75% (47–88) against single-antigen non-vaccine type strains. In middle-income settings, RV5 vaccine effectiveness was 70% (58–78) against single-antigen vaccine type strains, 37% (10–56) against partly heterotypic strains, and 87% (38–97) against single-antigen non-vaccine type strains. No difference was noted in vaccine effectiveness for either RV1 or RV5 in any setting (all p>0·05). Prevalent strains in countries using RV1 were G2P[4] (2198 of 4428, 50%) and G1P[8] (953, 22%), and those in countries using RV5 were G1P[8] (1280 of 3875, 33%) and G2P[4] (1169, 30%). Sustained predominance of a single strain was not recorded. Interpretation RV1 and RV5 exert similar effectiveness against homotypic and heterotypic rotavirus strains. Persistence of specific strains was not recorded, suggesting vaccine-induced selective pressure did not occur. Expansion of rotavirus surveillance efforts to low-income countries and ongoing surveillance are crucial to identify emergence of new strains and to assess strain-specific vaccine effectiveness in various settings. Funding None.
    The Lancet Infectious Diseases 09/2014; DOI:10.1016/S1473-3099(14)70832-1 · 19.45 Impact Factor
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    ABSTRACT: Estimates of population-based incidence for rotavirus inpatient and outpatient visits, as well as their associated medical costs, can provide valuable information to assess the potential benefits of rotavirus vaccination.
    The Pediatric Infectious Disease Journal 08/2014; 34(1). DOI:10.1097/INF.0000000000000505 · 3.14 Impact Factor
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    ABSTRACT: Rotavirus vaccines are being introduced in several low- and middle-income countries across the world with and without support from the GAVI Alliance. India has the highest disease burden of rotavirus based on morbidity and mortality estimates and several indigenous vaccine manufacturers are developing rotavirus vaccines. One candidate has undergone phase III testing and others have completed evaluation in phase II. Global data on licensed vaccine performance in terms of impact on disease, strain diversity, safety and cost-effectiveness has been reviewed to provide a framework for decision making in India.
    Vaccine 08/2014; 32:A171–A178. DOI:10.1016/j.vaccine.2014.03.029 · 3.49 Impact Factor
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    Vaccine 08/2014; 32:vii–xii. DOI:10.1016/j.vaccine.2014.05.047 · 3.49 Impact Factor
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    ABSTRACT: Serum antibodies play an important role in natural protection from rotavirus infection and disease, but conflicting estimates of association have emerged from epidemiological studies in different geographical settings. In this study, we aim to assess the relationship between pre-existing serum immunoglobulin (Ig)G and IgA titers with protection against rotavirus infection and disease in a birth cohort of Indian children. Children were recruited at birth and followed up for 36 months. Stool samples were collected every 2 weeks and during episodes of diarrhea and serum samples were obtained at least every 6 months. The incidence rate of rotavirus infection and diarrhea was 0.9 (95% CI: 0.88, 0.99) and 0.2 (95% CI: 0.19, 0.25) episodes per child year, respectively. The risk of rotavirus infection and diarrhea decreased with age, while antibody titers (IgG and IgA) increased with age. After adjusting for age and number of previous infections, higher levels of IgG and IgA were independently associated with reduced risk of rotavirus infection. However, we did not find a clear association of IgG or IgA with rotavirus diarrhea risk or a threshold level of protection. The study supports a correlation of serum antibodies in reducing the risk of rotavirus infections, however the potential of serum antibody titer as a correlate of protection is not clear for children in lower income settings.
    Vaccine 08/2014; 32, Supplement 1:A55-A61. DOI:10.1016/j.vaccine.2014.04.077 · 3.49 Impact Factor
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    ABSTRACT: In 1999, the first rotavirus vaccine licensed in the USA was withdrawn 9 months after introduction due to an association with intussusception that was detected in post-licensure surveillance. This association prompted large clinical trials designed to ensure the safety of two current live oral rotavirus vaccines, RotaTeq and Rotarix, which have since been recommended for use worldwide. Following their introduction, post-licensure studies have focused not only on the effectiveness and impact of these vaccines, but also on continued surveillance for intussusception. Most recent evidence from several countries shows a small increased risk of intussusception following vaccination with Rotarix and RotaTeq within the context of their demonstrated benefits. This review summarizes the available data on the safety of rotavirus vaccines with regards to intussusception.
    Expert Review of Vaccines 07/2014; 13(11). DOI:10.1586/14760584.2014.942223 · 4.22 Impact Factor
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    ABSTRACT: Since 2008, the World Health Organization (WHO) has coordinated the Global Rotavirus Surveillance Network, a network of sentinel surveillance hospitals and laboratories that report to ministries of health (MoHs) and WHO clinical features and rotavirus testing data for children aged <5 years hospitalized with acute gastroenteritis. In 2013, WHO conducted a strategic review to assess surveillance network performance, provide recommendations for strengthening the network, and assess the network's utility as a platform for other vaccine-preventable disease surveillance. The strategic review team determined that during 2011 and 2012, a total of 79 sites in 37 countries met reporting and testing inclusion criteria for data analysis. Of the 37 countries with sites meeting inclusion criteria, 13 (35%) had introduced rotavirus vaccine nationwide. All 79 sites included in the analysis were meeting 2008 network objectives of documenting presence of disease and describing disease epidemiology, and all countries were using the rotavirus surveillance data for vaccine introduction decisions, disease burden estimates, and advocacy; countries were in the process of assessing the use of this surveillance platform for other vaccine-preventable diseases. However, the review also indicated that the network would benefit from enhanced management, standardized data formats, linkage of clinical data with laboratory data, and additional resources to support network functions. In November 2013, WHO's Strategic Advisory Group of Experts on Immunization (SAGE) endorsed the findings and recommendations made by the review team and noted potential opportunities for using the network as a platform for other vaccine-preventable disease surveillance. WHO will work to implement the recommendations to improve the network's functions and to provide higher quality surveillance data for use in decisions related to vaccine introduction and vaccination program sustainability.
  • Jacqueline E Tate, Umesh D Parashar
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    ABSTRACT: Vaccines are now available to combat rotavirus, the most common cause of severe diarrhea among children worldwide. We review clinical trial data for available rotavirus vaccines and summarize post-licensure data on effectiveness, impact, and safety from countries routinely using these vaccines in national programs. In these countries, rotavirus vaccines have reduced all-cause diarrhea and rotavirus hospitalizations by 17%-55% and 49-92%, respectively, and all-cause diarrhea deaths by 22%-50% in some settings. Indirect protection of children age-ineligible for rotavirus vaccine has also been observed in some high and middle-income countries. Experience with routine use of rotavirus vaccines in low-income countries has been limited to date but vaccine introductions in such countries have been increasing in recent years. The risk-benefit analysis of rotavirus vaccines is extremely favorable but other strategies to improve the effectiveness of the vaccine, particularly in low-income settings, should be considered.
    Clinical Infectious Diseases 07/2014; 59(9). DOI:10.1093/cid/ciu564 · 9.42 Impact Factor
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    ABSTRACT: Background Despite substantial decreases in recent decades, acute gastroenteritis causes the second greatest burden of all infectious diseases worldwide. Noroviruses are a leading cause of sporadic cases and outbreaks of acute gastroenteritis across all age groups. We aimed to assess the role of norovirus as a cause of endemic acute gastroenteritis worldwide. Methods We searched Embase, Medline, and Global Health databases from Jan 1,2008, to March 8,2014, for studies that used PCR diagnostics to assess the prevalence of norovirus in individuals with acute gastroenteritis. We included studies that were done continuously for 1 year or more from a specified catchment area (geographical area or group of people), enrolled patients who presented with symptoms of acute gastroenteritis, and used PCR-based diagnostics for norovirus on all stool specimens from patients with acute gastroenteritis. The primary outcome was prevalence of norovirus among all cases of gastroenteritis. We generated pooled estimates of prevalence by fitting linear mixed-effect meta-regression models. Findings Of 175 articles induded, the pooled prevalence of norovirus in 187336 patients with acute gastroenteritis was 18% (95% CI 17-20). Norovirus prevalence tended to be higher in cases of acute gastroenteritis in community (24%, 18-30) and outpatient (20%, 16-24) settings compared with inpatient (17%, 15-19, p=0-066) settings. Prevalence was also higher in low-mortality developing (19%, 16-22) and developed countries (20%, 17-22) compared with high-mortality developing countries (14%, 11-16; p=0.058). Patient age and whether the study induded years of novel strain emergence were not associated with norovirus prevalence. Interpretation Norovirus is a key gastroenteritis pathogen associated with almost a fifth of all cases of acute gastroenteritis, and targeted intervention to reduce norovirus burden, such as vaccines, should be considered.
    The Lancet Infectious Diseases 06/2014; 14(8). DOI:10.1016/S1473-3099(14)70767-4 · 19.45 Impact Factor
  • The Journal of Infectious Diseases 06/2014; DOI:10.1093/infdis/jiu335 · 5.78 Impact Factor

Publication Stats

15k Citations
2,863.34 Total Impact Points


  • 1998–2015
    • Centers for Disease Control and Prevention
      • • Division of Viral Diseases
      • • National Center for Immunization and Respiratory Diseases
      • • National Center for Emerging and Zoonotic Infectious Diseases
      Атланта, Michigan, United States
    • University of Maryland, Baltimore
      • Department of Pediatrics
      Baltimore, Maryland, United States
  • 2012
    • University of Illinois, Urbana-Champaign
      Urbana, Illinois, United States
    • PATH
      Seattle, Washington, United States
  • 2011
    • Center for Adolescent Health and the Law
      North Carolina, United States
    • National Institute of Infectious Diseases, Tokyo
      Edo, Tōkyō, Japan
  • 2009
    • National Autonomous University of Nicaragua, Managua
      Μανάγκουα, Managua, Nicaragua
    • Malawi Centers of Disease Control and Prevention
      Lilongwe, Central Region, Malawi
    • University of Melbourne
      • Department of Paediatrics
      Melbourne, Victoria, Australia
  • 1998–2009
    • Emory University
      • • Centers for Disease Control and Prevention
      • • Department of Global Health
      • • Department of Pediatrics
      Atlanta, Georgia, United States
  • 2008
    • Queen Mary Hospital
      Hong Kong, Hong Kong
  • 2005
    • The Chinese University of Hong Kong
      Hong Kong, Hong Kong
    • Stanford University
      Palo Alto, California, United States
    • Cincinnati Children's Hospital Medical Center
      • Division of Infectious Diseases
      Cincinnati, Ohio, United States
  • 2000–2005
    • National Institute of Allergy and Infectious Diseases
      Maryland, United States
    • National Institute of Allergy and Infectious Disease
      Atlanta, Georgia, United States
  • 2004
    • Maryland Department of Health and Mental Hygiene
      Baltimore, Maryland, United States
  • 2001
    • U.S. Department of Health and Human Services
      • Centers for Disease Control and Prevention (CDC)
      Washington, D. C., DC, United States
  • 1999
    • Yale University
      New Haven, Connecticut, United States
    • The University of Arizona
      Tucson, Arizona, United States
    • Alpert Medical School - Brown University
      Providence, Rhode Island, United States