People who inject drugs (PWID) account for the majority of hepatitis C virus (HCV) infections in the United States. The injection-equipment-sharing network likely plays an important role in shaping the dynamics of HCV transmission. Recognizing the emerging HCV epidemic in rural communities, we developed an agent-based network simulation model of HCV transmission via injection equipment sharing and used data on rural PWID networks to inform model parameterization and calibration. We then simulated an array of networks that varied key network properties to understand their impact on the magnitude and distribution of HCV incidence. The results show substantial heterogeneity in HCV acquisition risks across the network, summarized using the Gini coefficient. In addition, although PWID with fewer injection partners had lower incidence, they collectively acquired more infections due to their larger population size. Higher prevalence, average number of partners, and homophily in HCV infection were associated with lower heterogeneity in infection risk across the network and higher overall incidence; other network properties including population size did not have a substantial impact. Our findings illustrate the heterogeneity of HCV transmission among PWID and suggest key network properties that could be measured, evaluated, or considered in the design of interventions for PWID in future studies.

BACKGROUND:Current hepatitis C virus (HCV) guidelines recommend testing at least once in a lifetime for all adults and periodic testing for people with ongoing risk factors. However, the testing frequency required for these populations including people who inject drugs (PWID) remains unknown. METHODS:We developed a dynamic network model to simulate HCV transmission among PWID via sharing of injection equipment. We simulated different testing frequencies among PWID, paired with a treatment cascade of direct-acting antiviral therapy, and compared their impact on HCV infection prevalence, incidence, and HCV-related deaths over 10 years. We conducted sensitivity analyses on key parameters and assumptions. RESULTS:In the main analysis, testing on average once per 6 months reduced HCV infection prevalence, incidence, and HCV-related deaths by up to 45%, 37%, and 42%, respectively. In the sensitivity analyses, increased coverage (access and utilization) had the greatest impact on all three outcomes, and reinfection risk after cure had a substantial impact on incidence. Lower transmission risk, higher cessation rate of injection, and longer partnership duration decreased the 3 outcomes with or without HCV testing. CONCLUSIONS:Frequent HCV testing with treatment had a substantial impact on hepatitis C elimination outcomes. However, it alone in the context of current continuum of care among PWID is unlikely to be sufficient to achieving elimination. Improving access to and utilization of hepatitis C care and harm-reduction services among PWID are crucial to achieving elimination.

BACKGROUND:Tuberculosis (TB) notifications and deaths in the United States fluctuated substantially during the coronavirus disease 2019 (COVID-19) pandemic. We analyzed multiple data sources to understand the factors contributing to these changes and estimated future TB trends. METHODS:We identified 4 mechanisms potentially contributing to observed TB trends during 2020-2023: immigration, respiratory contact rates, rates of accurate diagnosis and treatment initiation, and mortality rates for persons experiencing TB disease. We employed a Bayesian approach to synthesize evidence on how these mechanisms changed during the pandemic and how they might have combined to produce observed 2020-2023 TB data, using a transmission-dynamic model to link mechanisms to TB outcomes. We also simulated a no-pandemic-counterfactual scenario that assumed mechanisms followed pre-pandemic trends. We estimated TB outcomes associated with the pandemic until 2035 to capture lagged effects. We evaluated additional scenarios to estimate the individual effect of each mechanism. RESULTS:Over 2020-2035, we estimate an additional 2784 (95% uncertainty interval: 2164-3461) TB notifications and 1138 (1076-1201) TB deaths in the United States associated with changes occurring during the COVID-19 pandemic. Mechanisms had offsetting effects-decreases in TB diagnosis rates led to more TB deaths and notifications, while reductions in contact rates reduced TB deaths and notifications. Immigration changes initially reduced TB deaths, but increased deaths and notifications over time. Higher TB mortality rates increased TB deaths but decreased TB notifications. CONCLUSIONS:Although direct impacts of the COVID-19 pandemic occurred between 2020 and 2023, these changes may continue to influence TB incidence and mortality in future years.

Objective Evaluate the cost-effectiveness of telemedicine-based retinopathy of prematurity (ROP) screening strategies compared with binocular indirect ophthalmoscopy (BIO) and the current standard of care (no screening) in Sub-Saharan Africa. Design Decision-analytic cost-effectiveness analysis simulating costs and vision outcomes across alternative ROP screening strategies. Subjects A simulated cohort of 10,000 qualifying preterm infants (birth weight ≤ 2000 g or gestational age ≤ 32 weeks) in neonatal intensive care units across Ghana were modelled for each screening strategy. Methods Three strategies were compared: no screening, BIO, and telemedicine-based screening with non-physician graders. A hybrid telemedicine approach with 10% of images graded by physicians was also evaluated. The model estimated disease detection, treatment, and vision outcomes, and calculated costs and quality-adjusted life years (QALYs). Sensitivity analyses varied non-physician grader specificity, ROP incidence, and physician evaluation time for BIO. A willingness-to-pay (WTP) threshold of $2,238 per QALY (1× Ghana’s GDP per capita) was applied. Main Outcome Measures Incremental cost-effectiveness ratios (ICERs) expressed as cost per QALY gained and dominance relationships among strategies. Results Compared with no screening, telemedicine-based screening with non-physician graders yielded health benefits at a cost of $27 per QALY gained. Incorporating 10% physician grading into the telemedicine platform further improved outcomes at $1,331 per QALY gained relative to non-physician grading alone. BIO was strongly dominated by the hybrid telemedicine strategy. Sensitivity analyses identified non-physician grader specificity, disease incidence, and physician evaluation time for BIO as the most influential parameters; overall conclusions were robust across plausible ranges. Conclusions Telemedicine-based ROP screening, particularly a hybrid approach incorporating limited physician grading, appears to be a cost-effective strategy for implementation in Ghana and may be applicable to other countries in Sub-Saharan Africa.

SARS-CoV-2 infection rates displayed strikingly organized patterns of temporal and spatial spread as new variants were introduced and subsequently transmitted within the United States. While these spatio-temporal "waves" of infection have been described previously, attempts to quantify the speed and extent of these waves have been limited. Here, we estimate and compare the wavefront speed and spatial expansion of the first two major infection waves in the United States, illustrating these dynamics through detailed visualizations. Our findings reveal that the origins of these waves coincide with large gatherings and the relaxation of masking mandates. Notably, we found that the second wave spread more rapidly than the first, possibly driven by multiple introduction events. These analyses highlight regional heterogeneity in epidemic dynamics and underscore the importance of localized public health measures in mitigating ongoing outbreaks.

BACKGROUND:Effective immune protection against SARS-CoV-2 infection and severe COVID-19 disease continues to change due to viral evolution and waning immunity. We estimated population-level immunity to SARS-CoV-2 for each of the 50 United States (U.S.) and the District of Columbia from January 2020 through December 2023. METHODS:We updated a model of SARS-CoV-2 infections to align with the latest evidence on SARS-CoV-2 natural history and waning of immunity, and to integrate various data sources available throughout the pandemic. We used this model to produce population estimates of effective protection against SARS-CoV-2 infection and severe COVID-19 disease. RESULTS:On 30 December 2023, 98.6% of the U.S. population had experienced immunological exposure to SARS-CoV-2 through infection and/or vaccination, with 88.3% (95% credible interval: 78.4%, 95.5%) having had at least one SARS-CoV-2 infection. Despite this high exposure, the average population-level protection against infection was 31.6% (25.1%, 41.2%). Population-level protection against severe disease was 66.1% (59.2%, 74.3%). CONCLUSION:A new wave of SARS-CoV-2 infections and COVID-19-associated hospitalizations began near the end of 2023, with the introduction of the JN.1 variant. This upturn suggests that the U.S. population remains at risk of SARS-CoV-2 infection and severe COVID-19 disease despite the high level of cumulative exposure in the United States. This decline in effective protection is likely due to both waning and continued viral evolution.

Delays in identifying and treating individuals with infectious tuberculosis (TB) contribute to poor health outcomes and allow ongoing community transmission of M. tuberculosis (Mtb). Current recommendations for screening for tuberculosis specify community characteristics (e.g., areas with high local tuberculosis prevalence) that can be used to target screening within the general population. However, areas of higher tuberculosis burden are not necessarily areas with higher rates of transmission. We investigated the transmission of Mtb using high-resolution surveillance data in Blantyre, Malawi. We extracted and performed whole genome sequencing on mycobacterial DNA from cultured M. tuberculosis isolates obtained from culture-positive tuberculosis cases at the time of tuberculosis (TB) notification in Blantyre, Malawi between 2015-2019. We constructed putative transmission networks identified using TransPhylo and investigated individual and pair-wise demographic, clinical, and spatial factors associated with person-to-person transmission. We found that 56% of individuals with sequenced isolates had a probable transmission link to at least one other individual in the study. We identified thirteen putative transmission networks that included five or more individuals. Five of these networks had a single spatial focus of transmission in the city, and each focus centered in a distinct neighborhood in the city. We also found that approximately two-thirds of inferred transmission links occurred between individuals residing in different geographic zones of the city. While the majority of detected tuberculosis transmission events in Blantyre occurred between people living in different zones, there was evidence of distinct geographical concentration for five transmission networks. These findings suggest that targeted interventions in areas with evidence of localized transmission may be an effective local tactic, but will likely need to be augmented by city-wide interventions to improve case finding to have sustained impact.

BACKGROUND:Limited estimates exist on the population-level impact of partner notification (PN) for gonorrhea, with uncertainty in the influence of local epidemiology on PN effectiveness. An ecologic study in New York found a 6% reduction in diagnoses with a 10% increase in PN coverage. We estimated gonorrhea incidence reductions via PN across different epidemiologic conditions to compare the effects with the prior finding and to understand key determinants of variation. METHODS:We developed a stochastic network model of men who have sex with men and calibrated gonorrhea transmission dynamics to varied epidemiologic conditions. The population-level impact of increasing PN was summarized by incidence rate ratios (IRRs), and the relative importance of explanatory variables (including network density, baseline burden, and natural history parameters) was assessed via linear regression modeling of IRR and bootstrapping to evaluate uncertainty in estimation. RESULTS:We estimated an IRR of 0.97 (95% range, 0.93-0.99) for a 10% relative increase in PN coverage, comparable to the IRR of 0.94 (0.91-0.97) identified in the empirical study. PN retained effectiveness under diverse epidemiologic conditions. In a univariate sensitivity analysis, the strongest influence on IRR came from parameters governing index case testing probability, with an IRR of 0.93 when testing was at its highest. Other factors, such as network density, baseline incidence, and various natural history parameters, had relatively minor effects on the IRR. We observed larger individual-level benefits from PN for individuals with higher numbers of partners. CONCLUSIONS:Our findings support prior population-level estimates of the impact of PN on gonorrhea incidence.

Importance Periodic hepatitis C virus (HCV) testing is recommended for people who inject drugs (PWID), but the optimal testing frequency remains unknown. Objective To evaluate the health benefits, costs, and cost-effectiveness of alternative HCV testing frequencies for PWID. Design, Setting, and Participants This cost-effectiveness analysis extended a previously published agent-based network simulation model of HCV transmission through the sharing of injection equipment among PWID. Network-based HCV transmission was calibrated to longitudinal data from the Social Networks Among Appalachian People study and published literature on PWID networks in the US to evaluate HCV testing strategies in both a sparse PWID network setting with lower HCV transmission and a dense network setting with higher HCV transmission. Data were collected from November 2008 to August 2010, and data were analyzed from September 2017 to December 2019. Exposures Periodic HCV testing and treatment, with alternative average testing frequencies among PWID who have access to and use HCV care. Main Outcomes and Measures Changes in cumulative quality-adjusted life-years (QALYs) and health care costs over 60 years (in 2021 US dollars) and incremental cost-effectiveness ratios (ICERs) discounted at 3% annually. Results The mean initial age of 1552 simulated PWID was 32 years. Compared with no testing, HCV testing and treatment among PWID over a 10-year intervention period increased QALYs by 2.5% to 4.6% and costs by 0.5% to 2.3% across average testing frequencies ranging from once every 2 years to once monthly. In a lower transmission setting, testing every 2 years was weakly dominated by more frequent testing strategies; testing every year, every 6 months, every 3 months, and every month had ICERs of $6000 per QALY, $9300 per QALY, $24 200 per QALY, and $138 400 per QALY, respectively. In a higher transmission setting, testing every 2 years and every year were both weakly dominated, while testing every 6 months, every 3 months, and every month had ICERs of $14 000 per QALY, $30 100 per QALY, and $93 300 per QALY, respectively. Results were sensitive to risks of primary infection and reinfection as well as access to and utilization of HCV testing services among PWID. Conclusions and Relevance In this economic evaluation study, based on common benchmarks for cost-effectiveness, frequent HCV testing among PWID was cost-effective in both lower and higher transmission settings.

Background: During the COVID-19 pandemic, several US jurisdictions began to regularly report levels of SARS-CoV-2 in wastewater as a proxy for SARS-CoV-2 incidence. Despite the promise of this approach for improving COVID-19 situational awareness, the degree to which wastewater surveillance data agree with other data has varied, and better evidence is needed to understand the situations in which wastewater surveillance data track closely with traditional surveillance data. Objective: In this study, we quantified the statistical relationship between wastewater data and traditional case-based surveillance data for multiple jurisdictions. Methods: We collated data on wastewater SARS-CoV-2 RNA levels and COVID-19 case reports from July 2020 to March 2023 for 107 counties representing a range in terms of geographic location, population size, and urbanicity. For these counties, we used Bayesian hierarchical regression modeling to estimate the statistical relationship between wastewater data and reported cases, allowing for variation in this relationship across counties. We compared different model structural approaches and assessed how the strength of the estimated relationships varied between settings and over time. Results: Our analyses revealed a strong positive relationship between wastewater data and COVID-19 cases for the majority of locations, with a median correlation coefficient between observed and predicted cases of 0.904 (IQR 0.823-0.943). In total, 23/107 counties (21.5%) had correlation coefficients below 0.8, and 3/107 (2.8%) had values below 0.6. Across locations, the COVID-19 case rate associated with a given level of wastewater SARS-CoV-2 RNA concentration declined over the study period. Counties with greater population size (P<.001) and higher levels of urbanicity (P<.001) had stronger concordance between wastewater data and COVID-19 cases. Measures of model fit, and relationships with urbanicity and population size, were robust to sensitivity analyses in which we varied the time period of analysis and the sample of counties used for model fitting. Conclusions: In a sample of 107 US counties, wastewater surveillance had a close relationship with COVID-19 cases reported for the majority of locations, with these relationships found to be stronger in counties with greater population size and urbanicity. In situations where routine COVID-19 surveillance data are less reliable, wastewater surveillance may be used to track local SARS-CoV-2 incidence trends.

Quality-adjusted life years, or QALYs, are measures of health outcomes used in economic evaluations to capture changes in both quantity and quality of life due to health interventions. QALYs enable comparisons of diverse types of consequences on a common scale, quantifying health benefits in units of healthy years of life. In this article, we review the historical development and application of QALYs; summarize key concepts and theoretical foundations underlying QALYs; describe some of the leading alternatives that have been proposed; and offer a brief overview of QALY computations.

Introduction:While voluntary medical male circumcision (VMMC) reduces the individual-level risk of HIV acquisition by approximately 60% in randomised-controlled trials, little is known about the 'real-world' long-term effect of medical and traditional male circumcision on the cumulative risk of HIV infection. We estimate the association between these for the first time using a quasi-experimental study design-a household fixed-effects analysis-for sub-Saharan Africa, the global region with the largest HIV burden. Methods:We pooled individual-level cross-sectional data from the nationally-representative Demographic and Health Surveys and AIDS Indicator Surveys across all sub-Saharan African countries in which the surveys included data on both male circumcision and HIV status. We estimated the association between male circumcision and HIV status using modified Poisson regression models with household fixed-effects-which control for unobserved and observed confounding shared by men living in the same household-and included additional individual-level controls for demographic characteristics, socio-economic factors, and sexual behaviour. Results:We included individual data from 279,351 male participants in 48 nationally-representative surveys conducted in 29 countries between 2003-2018. The mean survey-level prevalence of male circumcision was 65.9% (median 84.5%, IQR 28.8%-68.1%) and HIV was 5.6% (median 2.5%, IQR 1.2%-10.2%). We estimated that male circumcision was significantly associated with a nearly one-fifth reduction in the cumulative risk of HIV infection (adjusted risk ratio 0.81, 95% CI 0.73-0.89). Conclusions:Male circumcision was associated with a significant reduction in the risk of HIV infection in sub-Saharan Africa over the past two decades. Increased political and financial commitment to VMMC could likely lead to further reductions in HIV prevalence, especially when rolled out as a HIV prevention option in combination with other interventions.

BACKGROUND:Host-response-based transcriptional signatures (HrTS) have been developed to identify "incipient tuberculosis (TB)". No study has reported the cost-effectiveness of HrTS for post-arrival migrant screening programs in low-incidence countries. The aim of this study was to assess the potential health impact and cost-effectiveness of HrTS for post-arrival TB infection screening among new migrants in the United States. METHODS AND FINDINGS:We used a discrete-event simulation model to compare four strategies: (1) no screening for TB infection or incipient TB; (2) 'IGRA-only', screen all with interferon-gamma release assay (IGRA), provide TB preventive treatment for IGRA-positives; (3) 'IGRA-HrTS', screen all with IGRA followed by HrTS for IGRA-positives, provide incipient TB treatment for individuals testing positive with both tests; and (4) 'HrTS-only', screen all with HrTS, provide incipient TB treatment for HrTS-positives. We assessed outcomes over the lifetime of migrants entering the United Stataes (U.S.) in 2019, assuming HrTS met WHO Target Product Profile (TPP) optimal criteria. We conducted sensitivity analyses to evaluate the robustness of results. Our findings show that at a willingness-to-pay threshold of $150,000 per quality-adjusted life-year (QALY) gained, the IGRA-only strategy was the optimal strategy under both healthcare sector and societal perspectives, with an incremental cost-effectiveness ratio (ICER) of $104,138 and $143,103 per QALY gained, respectively. At a willingness-to-pay of $100,000 per QALY gained the IGRA-HrTS strategy appeared optimal. When the cohort was stratified by TB incidence in the country-of-origin, the IGRA-only strategy was optimal for country-of-origin incidence [Formula: see text]100 per 100,000, and the no-screening strategy was optimal for country-of-origin incidence <10 per 100,000. The IGRA-HrTS strategy was potentially cost-effective with country-of-origin incidence of 10-100 per 100,000, though this result had substantial uncertainty. Results were sensitive to time trends in TB progression risk after U.S. entry. CONCLUSIONS:An HrTS test meeting WHO TPP optimal criteria would be potentially cost-effective for post-arrival screening among a subset of U.S. migrants, but this result was sensitive to multiple factors.

Preexposure prophylaxis (PrEP) is highly effective in preventing HIV infections and is recommended for people without HIV who are at ongoing risk of HIV acquisition. In 2019, the U.S. launched the “Ending the HIV Epidemic in the U.S.” initiative, which aims to reduce by 90 % the number of annual new HIV infections. To monitor progress towards this goal, several national indicators have been established, one of which is PrEP coverage. Several ways to monitor PrEP use have been developed, each with its own advantages and disadvantages. We developed a method to estimate PrEP “need” in the U.S. that could be used as a denominator to estimate PrEP coverage. The “population need for PrEP” (PPN) is estimated based on the number of people needed to treat (NNT) with PrEP to prevent an additional HIV infection in subpopulations whose annual HIV incidence is ≥ 1 %. This is done in three steps: 1) calculating NNT for each transmission group using 1 % incidence threshold and clinical trial-and cohort-generated evidence of the degree of PrEP effectiveness in each transmission group, 2) estimating the proportion of new HIV infections in subpopulations with incidence at least 1 % from epidemiologic data, 3) multiplying estimates from steps 1 and 2 with the number of new HIV infections for each transmission group from Surveillance. The estimates for each transmission group are then added together, and the number of current PrEP users is finally added to this estimate to produce PPN. This method is relatively easy to calculate and can provide public health authorities at the national, state, or local level with pragmatic estimates of PrEP “need” among different demographic or transmission groups, which can help with planning, resource allocation, and monitoring progress.

This cross-sectional study analyzes the use of 10 no-cost preventive services by individuals with employer-sponsored health insurance, which may be threatened by the upcoming Kennedy v Braidwood Supreme Court case.

BACKGROUND:In the United States, older adults have elevated prevalence of latent tuberculosis infection (LTBI) and incidence of tuberculosis (TB). OBJECTIVE:To estimate the health benefits and cost-effectiveness of LTBI testing and treatment among the Medicare-eligible population. DESIGN:Model-based cost-effectiveness analysis. DATA SOURCES:Nationally representative surveys and published evidence. TARGET POPULATION:Medicare-eligible persons aged 65 years or older with at least 1 of 15 factors associated with elevated TB risk, as identified by guidelines from the U.S. Preventive Services Task Force (USPSTF) and other organizations. TIME HORIZON:Lifetime. PERSPECTIVE:Societal. INTERVENTION:One-time offer of LTBI testing and treatment versus no intervention. OUTCOME MEASURES:Lifetime TB cases and deaths averted, quality-adjusted life-years (QALYs) gained, costs, and incremental cost-effectiveness ratios (ICERs). RESULTS OF BASE-CASE ANALYSIS:In 2022, there were an estimated 29.9 million Medicare-eligible persons (95% uncertainty interval [UI], 28.4 to 31.6 million persons) aged 65 years or older with elevated TB risks, including 14.7 million (95% UI, 13.4 to 16.0 million) with USPSTF-recommended factors. In the target population, 4.9 million persons (95% UI, 4.0 to 5.8 million persons) (16.4% [95% UI, 13.9% to 19.1%]) were estimated to have LTBI. Testing and treatment of LTBI was estimated to prevent 10 946 TB cases (95% UI, 4684 to 20 579 cases) and 2579 TB deaths (95% UI, 1106 to 4882 deaths), with 13 234 lifetime QALYs (95% UI, 5343 to 25 519 lifetime QALYs) gained. For the overall target population and for persons with USPSTF-recommended factors, ICERs were $192 000 (95% UI, $92 000 to $503 000) and $155 000 (95% UI, $77 000 to $393 000) per QALY gained, respectively. RESULTS OF SENSITIVITY ANALYSIS:The ICER was $109 000 (95% UI, $49 000 to $285 000) per QALY gained for 65-year-olds newly eligible for Medicare. LIMITATION:Health benefits from averted post-TB sequelae were not estimated. CONCLUSION:Medicare-eligible persons represent approximately one third of all U.S. persons with LTBI. Testing and treatment of LTBI in this population could lead to substantial reductions in TB and TB-related mortality, particularly among 65-year-olds newly eligible for Medicare. PRIMARY FUNDING SOURCE:Centers for Disease Control and Prevention.

Patients with chronic hepatitis B infection (CHB) have an increased risk for death from liver cirrhosis and hepatocellular carcinoma (HCC). In the United States, only an estimated 37% of adults with chronic hepatitis B diagnosis without cirrhosis receive monitoring with at least an annual alanine transaminase (ALT) and hepatitis B deoxyribonucleic acid (DNA), and an estimated 59% receive antiviral treatment when they develop active hepatitis or cirrhosis. A Markov model was used to calculate the costs, health impact and cost-effectiveness of increased monitoring of adults with HBeAg negative inactive or HBeAg positive immune tolerant CHB who have no cirrhosis or significant fibrosis and are not recommended by the current American Association for the Study of Liver Diseases (AASLD) clinical practice guidelines to receive antiviral treatment, and to assess whether the addition of HCC surveillance would be cost-effective. For every 100,000 adults with CHB who were initially not recommended for treatment, if the monitoring rate increased from the current 37% to 90% and treatment rate increased from 59% to 80%, 4,600 cases of cirrhosis, 2,450 cases of HCC and 4,700 HBV-related deaths would be averted with a gain of 45,000 QALYs and a savings of $180 million in lifetime health care costs. At a willingness to pay threshold of $100,000/QALY, the addition of HCC surveillance with the standard recommended biannual liver ultrasound and alfa fetoprotein levels is likely cost-effective if the HCC risk ≥ 0.55%/year. Regular monitoring of persons with inactive or immune tolerant CHB who are initially not recommended to receive antiviral treatment in the United States is cost-saving. The addition of HCC surveillance with biannual US and AFP would be cost-effective for individuals with HCC incidence ≥ 0.55%/year.

BACKGROUND:Chronic hepatitis D virus (HDV) infection increases the risk of liver-related deaths in adults with chronic hepatitis B (CHB). In the United States (US), only an estimated 12.9% of adults with CHB have received an HDV antibody test. The aim of this study is to calculate the cost-effectiveness of one-time universal HDV testing of hepatitis B surface antigen (HBsAg)-positive adults living in the US. METHODS:A Markov model was used to calculate the costs, health impact, and cost-effectiveness of universal testing of HBsAg-positive adults with an HDV antibody test and, when positive, an HDV RNA test for chronic HDV infection. We assumed that 50% of the HDV RNA-positive patients would receive the current recommended treatment with pegylated interferon (PEG-IFN) for 48 weeks with a 30% response rate. We also modeled the potential impact of hypothetical indefinite HDV antiviral therapy with a higher response rate to assess the annual cost threshold to be considered cost-effective. RESULTS:Universal HDV testing of adults with CHB could avert 100 HDV-related deaths and an additional 30 cases of cirrhosis and 50 cases of hepatocellular carcinoma, and potentially result in a gain of 1500 quality-adjusted life-years (QALYs) per 100 000 HBsAg-positive individuals screened. At a willingness-to-pay threshold of $50 000 per QALY, the annual drug costs for a hypothetical indefinite therapy with a 50% or 70% treatment response rate would need to cost ≤$13 027 and ≤$14 104, respectively. CONCLUSIONS:One-time HDV testing for all HBsAg-positive adults and treatment of chronic HDV infection with PEG-IFN is potentially cost-effective in the US.