Clinical Infectious Diseases

BACKGROUND AND OBJECTIVESSeasonal influenza vaccination has been shown to reduce the risk of influenza and severe complications among children 6 months and older. Since 2010, reported numbers of influenza-associated pediatric deaths among children aged <18 years have ranged from 37 during the 2011-2012 season to 289 during 2024-2025. We estimated influenza vaccine effectiveness (VE) against pediatric death from 2016-2017 through 2024-2025. METHODSWe conducted a case-cohort analysis comparing cu...

BackgroundWe previously reported that nasal SARS-CoV-2 viral loads (VL) peaked around the fourth day of symptoms in highly immune adults sampled April 2022 - April 2023, while influenza A VL peaked soon after symptom onset. We hypothesized that SARS-CoV-2 kinetics may have changed due to reduced COVID-19 incidence and altered vaccination patterns. Understanding how viral kinetics evolve over time is essential to inform testing strategies. MethodsParticipants with symptomatic upper respiratory i...

This study estimated early vaccine effectiveness (VE) of the BNT162b2 LP.8.1-adapted vaccine against emergency department/urgent care (ED/UC) and outpatient visits using a test-negative case-control design. Patients from the US Veterans Affairs Healthcare System with an acute respiratory infection (ARI) who underwent SARS-CoV-2 testing from September 10 - November 30, 2025 were included. VE was estimated using multivariable logistic regression adjusted for patient demographics and clinical chara...

To evaluate the impact of sex on acute SARS-CoV-2 infection, 668 participants from the ACTIV-2/A5401 study were followed over a 28-day period. A primary analysis was performed on the 469 participants who had quantifiable viral loads at baseline. Male and female participants had comparable nasal SARS-CoV-2 RNA levels at study entry and throughout follow-up. However, sex-specific differences in viral shedding emerged when stratified by duration of symptoms. In the first three days from symptom ons...

BackgroundPost-exposure prophylaxis with doxycycline (doxyPEP) within 72 hours after sex is recommended to prevent chlamydia, gonorrhea, and syphilis among United States men who have sex with men (MSM) and transgender women (TGW). However, concerns surround potential expansion of Neisseria gonorrhoeae lineages harboring antimicrobial resistance (AMR) in settings that implement doxyPEP. MethodsWe assessed the effectiveness of doxyPEP against chlamydia, gonorrhea, and syphilis among individuals r...

BackgroundImmunocompromised (IC) individuals are at increased risk for persistent SARS-CoV-2 infections and can develop new viral mutations and lineages not seen in the community. In this case report, a persistent SARS-CoV-2 infection (330 days) in an IC patient is examined for viral mutations and mutations associated with cryptic lineages. Case PresentationThe patient was followed in a longitudinal study examining persistent SARS-CoV-2 in IC patients. The patient provided stool and nasal swab ...

BackgroundSyphilis screening and treatment coverage remain lower than recommended among pregnant women in the US. ObjectiveWe estimated the prevalence and incidence of syphilis among pregnant women, incidence of congenital syphilis and the impact of improved prenatal care cascade by race and ethnicity. DesignCompartmental mathematical model of syphilis natural history, prenatal care, and syphilis screening and testing SettingUnited States ParticipantsPregnant women MeasurementsWomen were st...

ObjectiveTo quantify the seasonal burden of acute respiratory viral infections among healthcare workers (HCWs), characterize virologic etiologies, and identify predictors of symptomatic illness and sick leave. MethodsWe conducted a prospective cohort study of HCWs during winter 2024-2025, with weekly surveys capturing acute respiratory infections (ARI) and sick leave. Nasal-throat multiplex PCR swabs were self-collected during symptomatic episodes. Incidence rate ratios (IRRs) for symptomatic e...

BackgroundInfluenza vaccination prevents influenza and influenza-like illness (ILI) in children, but its potential influence on susceptibility to other respiratory viruses remains unclear. We aimd to evaluate the relationships between influenza/ILI, non-influenza respiratory virus (NIRV) infections, and influenza vaccination in children. MethodsWe conducted a retrospective cohort study using real-world data from the Italian Pedianet pediatric network, including children aged 6 months to 14 year...

BackgroundRespiratory syncytial virus (RSV) is a leading cause of severe acute respiratory infection in infants, young children and vulnerable adults. Despite implications for designing interventions, our understanding of RSV infection/reinfection patterns during community outbreaks is incomplete. MethodsTo characterize respiratory virus infections regardless of symptom status, we performed a prospective cohort surveillance in coastal Kenya from August 2023 to August 2024. Nasopharyngeal/oropha...

BackgroundHeartland virus (HRTV) is an emerging tick-borne virus capable of causing severe illness and death. The burden of disease is likely underestimated due to limited seroprevalence studies, lack of commercially available diagnostic tests, and an overlapping clinical syndrome with more commonly diagnosed bacterial diseases such as spotted fever group rickettsiosis or ehrlichiosis. MethodsActive surveillance for Heartland virus disease was conducted at a large academic center from March to ...

ObjectivesPneumococcal surveillance typically focuses on invasive disease (IPD), collecting limited clinical data. We used a longitudinal adult cohort of IPD and non-invasive pneumococcal disease (non-IPD) patients in three hospitals between 2006-22, to describe clinical disease, including site of infection, and serotype distribution. MethodsThe demographics of IPD and non-IPD were compared and survival analysis performed. Features of IPD in different sites were compared and serotype distributi...

BackgroundHousehold contact investigation for tuberculosis (TB) is limited by referral for clinic-based testing services. We evaluated the performance of in-home tongue swab (TS) testing among symptom-agnostic household contacts (HHC) to inform HCI screening strategies. MethodsWe conducted a prospective cohort study among HHC of TB patients in Eastern Cape, South Africa. In-home testing of sputum and TSs, with TSs pooled from up to three HHCs, was performed using Xpert Ultra on portable GeneExp...

ObjectiveThis study investigates the prevalence of human pegivirus (HPgV) in SARS-CoV-2-positive patients within the context of viral co-infections that may modulate COVID-19 outcomes and assesses whether HPgV co-infection is associated with COVID-19 severity. HPgV is a widely circulating but rarely monitored human virus with documented immunomodulatory effects in other viral infections, including HIV and Ebola. While HPgV prevalence is low in the general U.S. population (1-2%), it rises markedl...

BackgroundClostridium perfringens can cause life-threatening extraintestinal infections in immunocompromised patients, an area in which we have little information regarding strain factors that impact patient risks and outcomes. MethodsWe conducted genomic-epidemiologic analyses on C. perfringens isolates from 70 patients seen at Brigham and Womens Hospital over 2021-2024. Genomic analyses evaluated strain profiles within a broader context of 2,321 C. perfringens genomes from foodborne, veterina...

Background and objectiveRespiratory Syncytial Virus (RSV) can cause severe illness in adults, leading to respiratory and non-respiratory complications, functional decline, hospitalisation, and death. This study describes French patients aged [&ge;]50 years hospitalised with RSV (2015-2022) and their care pathways, including hospitalisation and outpatient healthcare use and costs. MethodsData were extracted from the French National Health Data System (SNDS). Patients were classified into four ri...

BackgroundSeasonal influenza imposes a significant clinical and economic burden in the United States despite the availability of effective vaccines. ObjectivesTo estimate the cost of illness associated with seasonal influenza among U.S. adults and to examine the relationship between vaccination coverage and influenza related outcomes. MethodsWe combined Centers for Disease Control and Prevention influenza burden estimates with contemporary healthcare utilization, cost, and labor market data to...

Annual influenza vaccination is the cornerstone for seasonal protection, yet antibody responses are highly variable across individuals and over time. To systematically assess the determinants of this heterogeneity, we compiled 20,449 hemagglutination inhibition and neutralization titers from 4,540 participants enrolled in 14 new vaccine studies we conducted and 50 prior studies that collectively span 2010-2023. Seasonal effects dominated, with pre- and post-vaccination titers declining steadily ...

A number of vaccines and long-acting monoclonal antibodies have been shown to be effective in the prevention of respiratory syncytial virus (RSV) disease. However, an immune correlate of protection for RSV has not yet been identified. We conducted a systematic review to identify published reports of immunogenicity and/or efficacy in vaccines and long-acting monoclonal antibodies against RSV and performed a meta-analysis on extracted data to identify any relationship between antibody increase and...

Household transmission of EV-D68 was identified in 35 of 1040 households (3.4%) in the Pacific Northwest between 2022-2024, with an estimated secondary attack rate of 15%. Sequences from within households clustered closely with 0 to 2 pairwise nucleotide differences (median 1) between cases 6-14 days apart (median 7).