Dataset Information

Home testing and counselling to reduce HIV incidence in a generalised epidemic setting: a mathematical modelling analysis.

ABSTRACT:

Background

Home HIV testing and counselling (HTC) achieves high levels of HIV testing and linkage to care. Periodic home HTC, particularly targeted to those with high HIV viral load, might facilitate expansion of antiretroviral therapy (ART) coverage. We used a mathematical model to assess the effect of periodic home HTC programmes on HIV incidence in KwaZulu-Natal, South Africa.

Methods

We developed a dynamic HIV transmission model with parameters, primary cost data, and measures of viral suppression collected from a prospective study of home HTC in KwaZulu-Natal. In our model, we assumed home HTC took place every 5 years with ART initiation for people with CD4 counts of 350 cells per μL or less. For individuals with CD4 counts of more than 350 cells per μL, we compared increasing ART coverage for those with 350-500 cells per μL with initiating treatment for those who have viral loads of more than 10 000 copies per mL.

Findings

Maintaining the presently observed level of 36% viral suppression in HIV-positive people, HIV incidence decreases by 33·8% over 10 years. Home HTC every 5 years with linkage to care with ART initiation at CD4 counts of 350 cells per μL or less reduces HIV incidence by 40·6% over 10 years. Expansion of ART to people with CD4 counts of more than 350 cells per μL who also have a viral load of 10 000 copies per mL or more decreases HIV incidence by 51·6%, and this was the most cost-effective strategy for prevention of HIV infections at US$2960 per infection averted. Expansion of ART eligibility CD4 counts of 350-500 cells per μL is cost-effective at $900 per quality-adjusted life-year gained. Following health economic guidelines, expansion of ART use to individuals who have viral loads of more than 10 000 copies per mL among those with CD4 counts of more than 350 cells per μL was cost-effective to reduce HIV-related morbidity.

Interpretation

Our results show that province-wide home HTC every 5 years can be a cost-effective strategy to increase ART coverage and reduce HIV burden. Expanded ART initiation criteria that includes individuals with high viral load will improve the effectiveness of home HTC in linking individuals to ART who are at high risk of transmitting HIV, thereby preventing morbidity and onward transmission.

Funding

National Institutes of Health.

SUBMITTER: Ying R

PROVIDER: S-EPMC4927306 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BackgroundThe long-term impact of universal home-based testing and treatment as part of universal testing and treatment (UTT) on HIV incidence is unknown. We made projections using a detailed individual-based model of the effect of the intervention delivered in the HPTN 071 (PopART) cluster-randomised trial.MethodsIn this modelling study, we fitted an individual-based model to the HIV epidemic and HIV care cascade in 21 high prevalence communities in Zambia and South Africa that were part of the PopART cluster-randomised trial (intervention period Nov 1, 2013, to Dec 31, 2017). The model represents coverage of home-based testing and counselling by age and sex, delivered as part of the trial, antiretroviral therapy (ART) uptake, and any changes in national guidelines on ART eligibility. In PopART, communities were randomly assigned to one of three arms: arm A received the full PopART intervention for all individuals who tested positive for HIV, arm B received the intervention with ART provided in accordance with national guidelines, and arm C received standard of care. We fitted the model to trial data twice using Approximate Bayesian Computation, once before data unblinding and then again after data unblinding. We compared projections of intervention impact with observed effects, and for four different scenarios of UTT up to Jan 1, 2030 in the study communities.FindingsCompared with standard of care, a 51% (95% credible interval 40-60) reduction in HIV incidence is projected if the trial intervention (arms A and B combined) is continued from 2020 to 2030, over and above a declining trend in HIV incidence under standard of care.InterpretationA widespread and continued commitment to UTT via home-based testing and counselling can have a substantial effect on HIV incidence in high prevalence communities.FundingNational Institute of Allergy and Infectious Diseases, US President's Emergency Plan for AIDS Relief, International Initiative for Impact Evaluation, Bill & Melinda Gates Foundation, National Institute on Drug Abuse, and National Institute of Mental Health.

Project description:Chickenpox is caused by varicella-zoster-virus (VZV) and is highly contagious. Immigration detention settings are a high-risk environment for primary VZV transmission, with large, rapidly-changing populations in close quarters, and higher susceptibility among non-UK-born individuals. During outbreaks, operational challenges occur in detention settings because of high-turnover and the potential need to implement population movement restriction for prolonged periods. Between December 2017 and February 2018, four cases of chickenpox were notified amongst 799 detainees in an immigration removal centre (IRC). Microbiological investigations included case confirmation by vesicular fluid polymerase chain reaction, and VZV serology for susceptibility testing. Control measures involved movement restrictions, isolation of cases, quarantining and cohorting of non-immune contacts and extending VZV immunity testing to the wider detainee population to support outbreak management. Immunity was tested for 301/532 (57%) detainees, of whom 24 (8%) were non-immune. The level of non-immunity was lower than expected based on the existing literature on VZV seroprevalence in detained populations in England. Serology results identified non-immune contacts who could be cohorted and, due to the lack of isolation capacity, allowed the placement of cases with immune detainees. The widespread immunity testing of all detainees was proving challenging to sustain because it required significant resources and was having a severe impact on operational capacity and the ability to maintain core business activities at the IRC. Therefore, mathematical modelling was used to assess the impact of scaling back mass immunity testing. Modelling demonstrated that interrupting testing posed a risk of one additional case compared to continuing with testing. As such, the decision was made to stop testing, and the outbreak was successfully controlled without excessive strain on resources. Operational challenges generated learning for future outbreaks, with implications for a local and national policy on IRC staff occupational health requirements, and proposed reception screening of detainees for VZV immunity.

Project description:BackgroundMany children who develop tuberculosis are thought to be missed by diagnostic and reporting systems. We aimed to estimate paediatric tuberculosis incidence and underreporting between 2013 and 2019 in countries representing more than 99% of the global tuberculosis burden.MethodsWe developed a mathematical model of paediatric tuberculosis natural history, accounting for key mechanisms and risk factors for infectious exposure (HIV, malnutrition, and BCG non-vaccination), the probability of infection given exposure, and progression to disease among infected individuals. We extracted paediatric population estimates from UN Population Division data, and we used WHO estimates for adult tuberculosis incidence rates. We parameterised this model for 185 countries and calibrated it using data from countries with stronger case detection and reporting systems. Using this model, we estimated trends in paediatric incidence, and the proportion of these cases that are diagnosed and reported (case detection ratio [CDR]) for each country, age group, and year.FindingsFor 2019, we estimated 997 500 (95% credible interval [CrI] 868 700-1 163 100) incident tuberculosis cases among children, with 481 000 cases (398 400-587 400) among those aged 0-4 years and 516 500 cases (442 900-608 000) among those aged 5-14 years. The paediatric CDR was estimated to be lower in children aged 0-4 years (41%, 95% CrI 34-50) than in those aged 5-14 years (63%, 53-75) and varied widely between countries. Estimated CDRs increased substantially over the study period, from 18% (15-20) in 2013 to 53% (45-60) in 2019, with improvements concentrated in the Eastern Mediterranean, South-East Asia, and Western Pacific regions. Over the study period, global incidence was estimated to have declined slowly at an average annual rate of 1·52% (1·42-1·66).InterpretationPaediatric tuberculosis causes substantial morbidity and mortality, and these data indicate that cases (and, thus, probably associated mortality) are currently substantially underreported. These findings reinforce the need to ensure prompt diagnosis and care for children developing tuberculosis, strengthen reporting systems, and invest in research to develop more accurate and easy-to-use diagnostics for paediatric tuberculosis in high-burden settings.FundingNational Institutes of Health.

Project description:BackgroundAntivirals (eg, oseltamivir) are important for mitigating influenza epidemics. In 2007, an oseltamivir-resistant influenza seasonal A H1N1 strain emerged and spread to global fixation within 1 year. This event showed that antiviral-resistant (AVR) strains can be intrinsically more transmissible than their contemporaneous antiviral-sensitive (AVS) counterpart. Surveillance of AVR fitness is therefore essential. Our objective was to develop a simple method for estimating AVR fitness from surveillance data.MethodsWe defined the fitness of AVR strains as their reproductive number relative to their co-circulating AVS counterparts. We developed a simple method for real-time estimation of AVR fitness from surveillance data. This method requires only information on generation time without other specific details regarding transmission dynamics. We first used simulations to validate this method by showing that it yields unbiased and robust fitness estimates in most epidemic scenarios. We then applied this method to two retrospective case studies and one hypothetical case study.FindingsWe estimated that the oseltamivir-resistant A H1N1 strain that emerged in 2007 was 4% (95% credible interval [CrI] 3-5) more transmissible than its oseltamivir-sensitive predecessor and the oseltamivir-resistant pandemic A H1N1 strain that emerged and circulated in Japan during 2013-14 was 24% (95% CrI 17-30) less transmissible than its oseltamivir-sensitive counterpart. We show that in the event of large-scale antiviral interventions during a pandemic with co-circulation of AVS and AVR strains, our method can be used to inform optimal use of antivirals by monitoring intrinsic AVR fitness and drug pressure on the AVS strain.InterpretationWe developed a simple method that can be easily integrated into contemporary influenza surveillance systems to provide reliable estimates of AVR fitness in real time.FundingResearch Fund for the Control of Infectious Disease (09080792) and a commissioned grant from the Health and Medical Research Fund from the Government of the Hong Kong Special Administrative Region, Harvard Center for Communicable Disease Dynamics from the National Institute of General Medical Sciences (grant number U54 GM088558), Area of Excellence Scheme of the Hong Kong University Grants Committee (grant number AoE/M-12/06).