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...

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 ...

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...

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 ...

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...

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).

BackgroundMycoplasma genitalium (MG) is an emerging sexually transmitted infection (STI) associated with pelvic inflammatory disease and tubal factor infertility. Its relationship with impaired fecundity remains unclear and is rarely examined in the context of co-seropositivity with other STIs. MethodsWe conducted a secondary analysis of the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial, a prospective preconception cohort of women with proven fecundity and prior pregnancy loss....

BACKGROUNDDiagnostic performance of tongue swab Mycobacterium tuberculosis PCR has been evaluated for facility-based triage of symptomatic tuberculosis (TB). It is unknown whether tongue swab performance differs for detection of asymptomatic TB in community-based screening. METHODSTongue swabs were collected from adult household contacts of TB patients (HHC Cohort), and symptomatic adults presenting to clinics with presumptive TB (Clinic Cohort), at eight South African sites. TB Cases were defi...

BackgroundLong COVID affects millions worldwide, yet the long-term trajectory of healthcare costs remains poorly characterized. Prior studies with limited follow-up have documented elevated but stable excess costs, leaving uncertainty about whether the economic burden attenuates or persists over time. MethodsWe conducted a retrospective cohort study using electronic health record data from 12 hospitals and 20 community health centers (January 2018 through December 2024). Adults with documented ...

BackgroundSerotype 3 (S3) has remained a major cause of invasive pneumococcal disease (IPD) despite its inclusion in 13-valent pneumococcal conjugate vaccine (PCV). In October 2023, a 15-valent PCV (PCV15) including S3 was introduced into the Catalan universal childhood immunization program. MethodsWe conducted a retrospective pre-post surveillance study to compare pediatric IPD incidence in Catalonia during a pre-PCV15 period (October 1, 2022-September 30, 2023) and two post-PCV15 periods (Oct...

BackgroundAfrica continues to have a significant public health problem with mpox, where endemic transmission persists and overlaps with a high burden of other infectious diseases. Although their epidemiology and clinical impact are still poorly understood throughout the continent, coinfections with human immunodeficiency virus (HIV) and varicella-zoster virus (VZV) can affect the clinical picture, severity of the disease, and accuracy of the diagnosis. MethodsFollowing PRISMA criteria, we regis...

Genomic surveillance of influenza viruses informs vaccine strain selection and evolutionary forecasting. Sequencing efforts vary widely across U.S. states, which raises concerns about spatial sampling bias. We evaluated how well 10,958 influenza virus genomes sampled by our group in Michigan captured the genetic diversity in 34,743 genomes circulating nationally from the 2021/22 through 2024/25 seasons. We defined seasonal hemagglutinin haplotypes and tracked their detection across states. A sma...

ObjectivesDespite the availability of effective vaccines, achieving the seroprevalence thresholds recommended by the World Health Organization (WHO) for eliminating measles, rubella, and mumps remains a public health challenge. MethodsA retrospective, cross-sectional serological survey was conducted, including 9,587 serum samples collected from 31 of the 32 federal entities of Mexico between September and December 2024. IgG antibody levels against measles, rubella, and mumps were quantified usi...

BackgroundTuberculosis (TB) incidence peaks in women during their reproductive years and is a leading cause of maternal mortality. Pregnant women with TB have a high risk of failure to initiate TB treatment and poor TB treatment and pregnancy outcomes. We determined the time to treatment initiation in pregnant women diagnosed with TB in a routine programmatic setting. MethodsUsing routine linked electronic data, we identified women 15-45 years of age with laboratory-confirmed and/or clinically ...

This exploratory analysis of PAX LC, a Phase 2, 1:1 randomized, double-blind, superiority, placebo-controlled trial examined whether treatment with nirmatrelvir/ritonavir (NMV/r) versus placebo/ritonavir (PBO/r) in individuals with Long COVID could reveal immune features associated with symptom improvement. Eighty-two participants (n=45 PBO/r; n=37 NMV/r) provided blood samples at baseline (Day 0) and post-treatment (Day 28). Baseline demographic and immunological phenotypes were similar in the ...

In the three years since Omicron emergence, SARS-CoV-2 dynamics have exhibited persistent twice-yearly waves in the United States, peaking in late summer and winter, with heterogeneity in timing and intensity across states. This semiannual pattern sharply contrasts with typical annual respiratory pathogen dynamics in the US, yet their underlying mechanisms and whether this pattern will persist remain poorly understood. Here, we tested several hypothesized mechanisms and found that a combination ...

BackgroundThe SARS-CoV-2 LP.8.1 subvariant was incorporated into the 2025-2026 U.S. COVID-19 vaccines (mRNA-1273.251 and mRNA-1283.251). We evaluated immunogenicity and safety of these vaccines against vaccine-matched and emerging variants in individuals aged [&ge;]65 and those aged 12-64 years at high-risk of severe COVID-19. MethodsData were generated from: (1) two independent, ongoing, phase 3b/4, open-label, single-arm studies in which participants received a single dose of 50-{micro}g mRNA...