Publications by authors named "Hammitt L"

Background: Pneumococcal conjugate vaccines (PCVs) introduced in childhood national immunization programs lowered vaccine-type invasive pneumococcal disease (IPD), but replacement with non-vaccine-types persisted throughout the PCV10/13 follow-up period. We assessed PCV10/13 impact on pneumococcal meningitis incidence globally.

Methods: The number of cases with serotyped pneumococci detected in cerebrospinal fluid and population denominators were obtained from surveillance sites globally.

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Bacterial genomes exhibit significant variation in gene content and sequence identity. Pangenome analyses explore this diversity by classifying genes into core and accessory clusters of orthologous groups (COGs). However, strict sequence identity cutoffs can misclassify divergent alleles as different genes, inflating accessory gene counts.

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Article Synopsis
  • The text discusses the impact of pneumococcal conjugate vaccines (PCVs), specifically PCV10 and PCV13, on invasive pneumococcal disease (IPD) globally, highlighting how these vaccines have reduced the prevalence of disease caused by vaccine-type serotypes after extensive use.
  • It describes the methodology of data collection from various surveillance sites, which aimed to evaluate IPD cases that occurred five years after the vaccines were implemented, focusing on different age groups for analysis.
  • Findings indicate significant differences in serotype distribution between PCV10 and PCV13 sites; notably, certain serotypes, such as 19A and serotype 3, were prevalent in specific age groups, signaling ongoing challenges in controlling
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Background: Pneumococcal conjugate vaccines (PCVs) that are ten-valent (PCV10) and 13-valent (PCV13) became available in 2010. We evaluated their global impact on invasive pneumococcal disease (IPD) incidence in all ages.

Methods: Serotype-specific IPD cases and population denominators were obtained directly from surveillance sites using PCV10 or PCV13 in their national immunisation programmes and with a primary series uptake of at least 50%.

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Background: Nirsevimab is an extended half-life, highly potent neutralizing monoclonal antibody against the respiratory syncytial virus (RSV) fusion protein, with efficacy in preventing RSV-associated medically attended (MA) lower respiratory tract infection (LRTI) in infants and medically vulnerable children (aged ≤24 months). This post-hoc exploratory analysis examined the incidence of LRTI from RSV and other respiratory pathogens during a 2:1 randomized, double-blind, placebo-controlled, phase 3 study of nirsevimab, in healthy-term and late-preterm (i.e.

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  • * A study conducted with 19 Indigenous adults in the Southwest explored their experiences, revealing barriers like fear of exposure and discomfort with testing, as well as worries about vaccine side effects and confusion over eligibility.
  • * Identifying these barriers and facilitators can inform public health efforts to enhance testing and vaccination in Indigenous communities, ultimately helping to reduce COVID-19 transmission.
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  • The study investigated the prevalence and characteristics of human metapneumovirus (hMPV) in children with severe pneumonia across seven African and Asian countries, finding a significant correlation between hMPV and pneumonia cases compared to community controls.
  • HMPV was more frequently detected in hospitalized pneumonia cases (6.9%) than in controls (2.3%), with a notable negative association with RSV and a positive association with bacterial infections.
  • The majority of hMPV-positive cases were infants under one year, with low mortality rates similar to those of RSV-positive cases, indicating that hMPV pneumonia is challenging to distinguish from RSV pneumonia in clinical settings.
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SARS-CoV-2 antibody kinetics based on immunologic history is not fully understood. We analyzed anti-spike and anti-nucleocapsid antibody responses following acute infection in a cohort of Indigenous persons. The models of peak concentrations and decay rates estimated that one year after infection, participants would serorevert for anti-nucleocapsid antibodies and remain seropositive for anti-spike antibodies.

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Objectives: American Indian and Alaska Native (AI/AN) infants historically experienced a disproportionate burden of invasive Haemophilus influenzae type b (Hib) disease, especially early in life. PedvaxHIB vaccine is preferentially recommended for AI/AN infants because it elicits protective antibody levels postdose 1. Vaxelis, a hexavalent vaccine that contains the same Hib conjugate as PedvaxHIB but at lower concentration, is recommended for US children, but postdose 1 Hib immunogenicity data are needed to inform whether a preferential recommendation should be made for AI/AN infants.

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After introducing pneumococcal conjugate vaccines (PCVs), serotype replacement occurred in . Predicting which pneumococcal strains will become common in carriage after vaccination can enhance vaccine design, public health interventions, and understanding of pneumococcal evolution. Invasive pneumococcal isolates were collected during 1998-2018 by the Active Bacterial Core surveillance (ABCs).

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Despite use of highly effective conjugate vaccines, invasive pneumococcal disease (IPD) remains a leading cause of morbidity and mortality and disproportionately affects Indigenous populations. Although included in the 13-valent pneumococcal conjugate vaccine (PCV13), which was introduced in 2010, serotype 3 continues to cause disease among Indigenous communities in the Southwest USA. In the Navajo Nation, serotype 3 IPD incidence increased among adults (3.

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BACKGROUNDCOVID-19 convalescent plasma (CCP) virus-specific antibody levels that translate into recipient posttransfusion antibody levels sufficient to prevent disease progression are not defined.METHODSThis secondary analysis correlated donor and recipient antibody levels to hospitalization risk among unvaccinated, seronegative CCP recipients within the outpatient, double-blind, randomized clinical trial that compared CCP to control plasma. The majority of COVID-19 CCP arm hospitalizations (15/17, 88%) occurred in this unvaccinated, seronegative subgroup.

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Introduction: In 2012, the World Health Organization revised treatment guidelines for childhood pneumonia with lower chest wall indrawing (LCWI) but no 'danger signs', to recommend home-based treatment. We analysed data from children hospitalized with LCWI pneumonia in the Pneumonia Etiology Research for Child Health (PERCH) study to identify sub-groups with high odds of mortality, who might continue to benefit from hospital management but may not be admitted by staff implementing the 2012 guidelines. We compare the proportion of deaths identified using the criteria in the 2012 guidelines, and the proportion of deaths identified using an alternative set of criteria from our model.

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Background: Haemophilus influenzae (Hi) can cause severe disease in children. This study aimed to identify risk factors related to invasive Hi disease in Alaska children and evaluate carriage in people around them.

Methods: From 2005 to 2011, we investigated episodes of invasive, typeable Hi disease in Alaska children <10 years old.

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Otitis media-associated outpatient visits among American Indians/Alaska Natives children <5 years old decreased by 52% (100 to 48 per 100 children per year) from 2003 to 2019. Otitis media visits decreased by another 50% from 2019 to 2020, but rebounded between 2020 and 2021 back to a rate similar to 2019.

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Article Synopsis
  • The Phase 3 MELODY trial evaluated the effectiveness of nirsevimab in preventing RSV in children during their second RSV season.
  • Results showed that there was no increase in medically attended RSV lower respiratory infections or disease severity in children who received nirsevimab compared to those who received a placebo.
  • The clinical trial is registered at Clinicaltrials.gov under NCT03979313, confirming its scientific validity.
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Background: After introduction of pneumococcal conjugate vaccines (PCVs), serotype replacement occurred in the population of Predicting which pneumococcal clones and serotypes will become more common in carriage after vaccination can enhance vaccine design and public health interventions, while also improving our understanding of pneumococcal evolution. We sought to use invasive disease data to assess how well negative frequency-dependent selection (NFDS) models could explain pneumococcal carriage population evolution in the post-PCV13 epoch by weighting invasive data to approximate strain proportions in the carriage population.

Methods: Invasive pneumococcal isolates were collected and sequenced during 1998-2018 by the Active Bacterial Core surveillance (ABCs) from the Centers for Disease Control and Prevention (CDC).

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  • The study investigates the impact of the COVID-19 pandemic on the hospitalization rates and severity of respiratory syncytial virus (RSV) infections in children under 5 years old.
  • It included a systematic review of 61 studies from 19 countries, utilizing both published and unpublished data to assess changes in RSV epidemiology during the pandemic compared to 2019.
  • Results showed hospitalization rates and severity of RSV-related acute lower respiratory infections (ALRI) significantly changed during the pandemic, with most studies coming from high-income countries.
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This study examined the role that cytokines may have played in the beneficial outcomes found when outpatient individuals infected with SARS-CoV-2 were transfused with COVID-19 convalescent plasma (CCP) early in their infection. We found that the pro-inflammatory cytokine IL-6 decreased significantly faster in patients treated early with CCP. Participants with COVID-19 treated with CCP later in the infection did not have the same effect.

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Approximately 20% of individuals infected with SARS-CoV-2 experienced long-term health effects, as defined PCC. However, it is unknown if there are any early biomarkers associated with PCC or whether early intervention treatments may decrease the risk of PCC. In a secondary analysis of a randomized clinical trial, this study demonstrates that among outpatients with SARS-CoV-2, increased IL-6 at time of infection is associated with increased odds of PCC.

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Background: Cytokines and chemokines play a critical role in the response to infection and vaccination. We aimed to assess the longitudinal association of COVID-19 vaccination with cytokine and chemokine concentrations and trajectories among people with SARS-CoV-2 infection.

Methods: In this longitudinal, prospective cohort study, blood samples were used from participants enrolled in a multi-centre randomised trial assessing the efficacy of convalescent plasma therapy for ambulatory COVID-19.

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Background: COVID-19 convalescent plasma (CCP) is an important therapeutic option for outpatients at high risk of hospitalization from SARS-CoV-2 infection. We assessed the safety of outpatient CCP transfusions administered during clinical trials.

Study Design And Methods: We analyzed data pertaining to transfusion-related reactions from two randomized controlled trials in the U.

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  • In Kilifi, Kenya, the introduction of the pneumococcal conjugate vaccine (PCV10) in 2011 led to increased levels of protective antibodies in infants, as shown by serological surveys between 2009 and 2017.
  • The study observed a significant rise in the proportion of infants with protective antibody levels right after the vaccine was introduced, with rates jumping from 0-33% in 2009 to 60-94% in 2011.
  • While IgG levels generally waned quickly after infancy, children aged 10-14 years maintained high antibody concentrations, suggesting ongoing immunity likely due to previous exposure or memory responses to related antigens.
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