About

Adam Akullian is a Senior Research Scientist at the Institute for Disease Modeling (IDM) within the Gates Foundation and an Affiliate Associate Professor in the Department of Global Health at the University of Washington. He holds a Ph.D. in Epidemiology from the University of Washington and an Sc.B. in Environmental Science from Brown University. His research focuses on geospatial, mathematical, and epidemiological modeling of HIV/AIDS in sub-Saharan Africa, with the goal of understanding HIV transmission dynamics, assessing the impact of long-acting PrEP on incidence, and utilizing novel AI methodologies for risk assessment.

Research topics

• Pathology
• Medicine
• Environmental health
• Internal medicine
• Gerontology
• Demography

Selected publications

• Comparing modelled HIV incidence estimates with empirical HIV incidence observations in high-burden HIV African epidemic settings: systematic review and meta-regression

  medRxiv · 2026-02-05 · 2 citations

  articleOpen access

  Abstract Background HIV incidence in sub-Saharan Africa has declined substantially since 2000 according to epidemic estimates published by UNAIDS. These estimates, derived by fitting mathematical models to national surveillance data, guide HIV programmes and epidemic response strategies. We assessed whether the level and age distribution of HIV incidence from modelled estimates were consistent with empirical HIV incidence observations, and whether incidence levels and trends were systematically different between study types, populations, and age groups. Methods We conducted an updated systematic review of adult HIV incidence data from sub-Saharan Africa published July 2019-February 2024 by searching Scopus, PubMed, Embase, and OVID databases, and combined with earlier systematic review data. We matched empirical incidence measurements between 1990-2023 to UNAIDS HIV incidence estimates by study area, sex, age group, and year. We used Bayesian mixed-effect Poisson regression to estimate (1) incidence rate ratios (IRR) between empirical observations and matched modelled incidence estimates adjusted for sex, year and study type/population; and (2) time trends in age-specific incidence from population-based cohort studies and household surveys. Results 3560 HIV empirical incidence measurements were included from 179 studies conducted in 21 countries, comprising 23,000 new infections and 3.1 million person-years. Incidence observations from nationally-representative household surveys (IRR 1.07 95%CI 0.68, 1.67) and population-representative study populations (IRR 0.98 95%CI 0.51, 1.89) were not significantly different from matched modelled estimates, and declined at the same rate as modelled estimates (annual aRR 0.99 95%CI 0.98, 1.01). Studies among pregnant women (IRR 2.60 95%CI 1.58, 4.28), control arms of clinical trials (IRR 3.01 95%CI 1.90, 4.77) and key populations (FSW IRR: 6.46 95%CI 4.18, 10.00; MSM 44.02 95%CI 27.35, 70.87) had significantly higher incidence than modelled total population incidence estimates. Across population cohorts in Eastern and Southern Africa, HIV incidence among adults aged 15-49 declined by 75-90% between 2010-2023, and declined 7% (95%CI 4-10%) faster per year among young adults 15-24 compared to age 25+ years. Modelled incidence declined similarly to cohort data, but did not reflect the aging of the epidemic. Conclusion Observed incidence in population-representative studies in sub-Saharan Africa has declined steeply. Mathematical models that infer incidence from cross-sectional HIV surveillance data estimated the same incidence level and decline over time as population-representative studies. Studies with non-representative inclusion criteria had significantly higher incidence, including those among pregnant women and most HIV prevention/vaccine efficacy trials. The age pattern of incidence in modelled estimates should be reconsidered to capture the aging of the epidemic indicated by cohort studies.

  PublisherOA PDFDOI

• Health and economic impact of geographically prioritized long-acting PrEP delivery in southern and eastern Africa

  medRxiv · 2026-02-26

  articleOpen access1st authorCorresponding

  Abstract Background Long-acting injectable HIV pre-exposure prophylaxis (PrEP), including Lenacapavir, has the potential to accelerate HIV incidence declines in eastern and southern Africa (ESA). However, high product and delivery costs and constrained budgets necessitate efficient prioritization strategies to maximize impact and achieve cost-effectiveness. Methods We used district-level HIV incidence estimates published by UNAIDS to estimate the direct health and economic impact of prioritizing Lenacapavir delivery according to geography, age, and sex across 837 districts in 11 high-burden ESA countries. Infections and disability-adjusted life years (DALY) averted, number needed to treat (NNT), cost per DALY averted, and price thresholds to achieve cost-effectiveness were estimated across geographic prioritization scenarios. Cost-effectiveness was assessed against a $500 per DALY averted threshold, assuming $5,000 discounted lifetime HIV treatment costs and 10 DALYs per HIV infection. Sensitivity analyses varied Lenacapavir costs (commodities + delivery) per person per year (pppy) ($125 versus $55), DALYs per HIV infection (7.5), and the risk differentiation among those who uptake long-acting PrEP. Results HIV incidence varied substantially across ESA, with 50% of new infections in districts containing less than 20% of at-risk adults. Lenacapavir cost-effectiveness varied accordingly, with high-incidence districts exhibiting substantially lower NNT and higher price thresholds for cost-effective delivery. In high-incidence districts, [>5/1,000 person-years (py)], of South Africa, Mozambique, Lesotho, and eSwatini, Lenacapavir would be cost-effective at $50-100 pppy. In South Africa, at annual cost $55 pppy, Lenacapavir was cost-effective in all 52 districts when provided to women aged 15–24 years with incidence exceeding twice the district average and could reach approximately 18–20% of new infections while covering 4% of the full HIV-negative adult population aged 15–49 years. Geographically optimized prioritization in South Africa with minimal age and risk-group stratification achieved efficiency comparable to country-level prioritization to high-risk groups and key populations (∼20% incidence reduction with 3–5% coverage). Impact and cost-effectiveness were sensitive to assumptions about risk heterogeneity. Conclusions Lenacapavir impact and cost-effectiveness varies substantially across geographic settings, driven primarily by variation in HIV incidence. Simple incidence-based models can identify where universal provision to certain demographic groups is both impactful and cost-effective, particularly in high-incidence districts and age groups.

  PublisherOA PDFDOI

• Geospatial mobility, non-local partners, concurrent sexual partnerships, and gender influence longitudinal STI prevalence in rural eastern Africa

  International Journal of STD & AIDS · 2026-03-18

  articleOpen access

  Background Mobility challenges HIV prevention efforts through associated risk behaviours and sexually transmitted infections (STIs). We characterized relationships between mobility and sexual risks on STI prevalence over time in East Africa. Methods Geospatial mobility and sexual risk behaviours were collected in 12 communities using a sex- and HIV-stratified random sub-sample of 2750 adults from a longitudinal cohort (2015–2019) of a HIV test-and-treat trial in Kenya and Uganda. Annual Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) testing was performed and relationships of prevalent STIs with mobility, sexual concurrency, and higher HIV-risk sexual partners (defined as one night stand, stranger, commercial sex worker/client, casual partner, or inherited partner/inheritor) were examined. Results The annual prevalence of CT or NG among 2665 participants tested was 3.1% (95% CI: 2.5–3.9) at baseline, 3.3% (95% CI: 2.6–4.0) at year 1, 4.4% (95% CI: 3.0–5.2) at year 2, and 4.8% (95% CI: 4.0–5.7) at year 3. STI (CT, NG) prevalence was associated with migration in the past year, sexual partnership concurrency, being single, higher HIV-risk partners, age >25, low household wealth, and the relationship between gender and work-related travel in past 6 months. The association between select STI prevalence and past 6-months travel was mediated by higher HIV-risk sexual partners, partnership concurrency, out-of-town partner, and higher HIV-risk transactional sex partners. Conclusions Geospatial mobility, sexual concurrency, and higher HIV-risk partnerships significantly influence longitudinal CT and/or NG prevalence in East Africa.

  PublisherDOI

• Evaluating the biomedical and behavioral drivers of HIV incidence decline in adolescent girls and young women in Uganda: A mathematical modeling study

  PLoS Medicine · 2026-03-25

  articleOpen access1st authorCorresponding

  BACKGROUND: HIV incidence among adolescent girls and young women (AGYW) in eastern and southern Africa has declined substantially over the past two decades. These declines are often attributed to biomedical HIV prevention strategies, though concurrent changes in sexual behavior may also contribute. We evaluated the contributions of biomedical and behavioral drivers to historical incidence decline in AGYW and projected their impact on incidence trajectories over the next 30 years. METHODS AND FINDINGS: We conducted a mathematical modeling study using data from the Rakai Community Cohort Study (RCCS), an open, population-based cohort of adults aged 15-49 years in 30 communities in Rakai, Uganda. We used an agent-based HIV-1 transmission model calibrated to cohort data to estimate HIV incidence trends among AGYW, aged 15-24, and to quantify the independent and combined effects of antiretroviral therapy (ART), voluntary medical male circumcision (VMMC), and changes in age at first sex (AFS). HIV incidence among women aged 15-24 declined by 71% between 2000 and 2019, from 1.57 to 0.45 per 100 person-years, representing the largest decline across female age groups in the cohort. Increasing AFS over the study period (by approximately 3 years in women and 2 years in men) was the largest contributor to incidence declines among adolescent women aged 15-19, averting 17% of cumulative infections between 2000 and 2020 and 37% between 2000 and 2050. Among women aged 20-24, ART scale-up had the greatest impact, averting 13% of infections by 2020 and 43% by 2050. VMMC contributed modestly to historical declines but had larger projected effects over longer time horizons. ART, VMMC, and delays in AFS acted additively to reduce HIV incidence among AGYW. Study limitations include reliance on self-reported sexual behavior and the use of a mathematical model that cannot capture all real-world sexual network dynamics. CONCLUSIONS: Both biomedical HIV interventions and broader behavioral changes contributed to declines in HIV incidence among AGYW. Sustaining continued incidence declines in young women will require maintaining both the protective changes in sexual behaviors and effective biomedical interventions.

  PublisherDOI

• Effects of reductions in US foreign assistance on HIV, tuberculosis, family planning, and maternal and child health: a modelling study

  The Lancet Global Health · 2025-09-17 · 28 citations

  articleOpen access

  BACKGROUND: The USA has traditionally been the largest donor to health programmes in low-income and middle-income countries (LMICs). In January 2025, almost all such funding was stopped and prospects for its resumption are uncertain. The suddenness of the funding cuts makes it difficult for national health programmes in LMICs to adapt. We aimed to estimate the impact of these cuts on deaths and other outcomes (new infections, number of family planning users, and unplanned pregnancies) for four health areas that have been a focus of a substantial amount of US foreign assistance: HIV, tuberculosis, family planning, and maternal and child health. METHODS: We applied established mathematical models to the countries receiving US foreign assistance in each domain to estimate health impacts over the period 2025 to 2030. We used six models of HIV, three different approaches to estimate family planning impact, and one model each for tuberculosis and maternal and child health, applying these models to as many as 80 countries. We compared model projections assuming constant funding (status quo) with projections assuming complete elimination of US funding in each country. Some models also considered partial cuts or restoration of funding over time. FINDINGS: A complete cessation of US funding without replacement by other sources would lead to drastic increases in deaths from 2025 to 2030: 4·1 million (range 1·6-6·6) additional AIDS-related deaths across 55 countries, 606 900 (95% uncertainty interval [UI] 466 000-768 800) additional tuberculosis deaths across 79 countries, 40-55 million additional unplanned pregnancies and 12-16 million unsafe abortions across 51 countries, and 2·5 million (1·3-4·5) additional child deaths from causes other than HIV and tuberculosis across 24 countries. Restoration of funding for HIV treatment but not prevention would avoid most of the increase in deaths but still result in nearly 1 million more new HIV infections from 2025 to 2030. INTERPRETATION: Substantial progress has been made in improving global health in the past few decades. This progress has strengthened hope in reaching global development goals. However, the recent funding cuts threaten to change these trajectories and could lead to sharp increases in avoidable mortality for the poorest countries. Even a partial restoration of US funding would combat the most severe effects and provide time for countries that have received substantial US foreign assistance to adjust to the new funding landscape. FUNDING: Economic and Social Research Council; Engineering and Physical Sciences Research Council; European and Developing Countries Clinical Trials Partnership; Gates Foundation; Global Fund to Fight AIDS, Tuberculosis, and Malaria; Open Philanthropy; UK Foreign, Commonwealth & Development Office; UK Medical Research Council; UN Population Fund; UNAIDS; US National Institute of Allergy and Infectious Diseases; University of Edinburgh; US National Institutes of Health; US President's Emergency Plan for AIDS Relief; Wellcome Trust; World Bank; WHO.

  PublisherOA PDFDOI

• Evaluating the biomedical and behavioural drivers of HIV-1 incidence decline in adolescent girls and young women in Uganda: A mathematical modelling study

  medRxiv · 2025-01-12

  preprintOpen access1st authorCorresponding

  Background: Recent declines in HIV incidence among adolescent girls and young women (AGYW) in Africa are often attributed to the expansion of biomedical interventions such as antiretroviral therapy and voluntary medical male circumcision. However, changes in sexual behaviour may also play a critical role. Understanding the relative contributions of these factors is essential for developing strategies to sustain and further reduce HIV transmission. Methods: We conducted a mathematical modelling study of data from the Rakai Community Cohort Study (RCCS), an open, population-based cohort of 15- to 49-year-olds in 30 communities in Rakai, Uganda, to investigate the biomedical and behavioural drivers of HIV incidence decline in AGYW (15-24 years of age). We estimated changes in the HIV incidence rate between 2000-2019 using retrospective cohort data to validate our modelled incidence estimates. We ran modelled counterfactual scenarios to quantify the independent and combined effects (cumulative infections averted and difference in incidence rates) of antiretroviral therapy (ART), voluntary medical male circumcision (VMMC), and delays in age of first sex (AFS) over historical (between 2000-2020) and projected (between 2000-2050) time horizons. Findings: Incidence in women 15-24 years of age declined by 83% between 2000-2019 (from 1.72 per 100 person-years in 2000 to 0.30 per 100 person-years in 2019), the largest reduction in incidence of all age groups of women. Increasing AFS over the last two decades (by 3 years in women and 2 years in men) was the largest contributor to incidence decline in women 15-19 years of age, averting 17% of cumulative infections between 2000-2020 and 37% between 2000-2050. Incidence in 15-19-year-old women was 69% lower in 2020 and 75% lower in 2050 compared to counterfactual scenarios without changes in AFS. ART scale-up contributed the most to incidence declines among women 20-24 years of age, averting 13% of infections between 2000-2020 and 43% of infections between 2000-2050. VMMC averted < 5% of infections in 15-24-year-olds to-date, with larger reductions in incidence between 2000-2050 in both 15-19 year-olds (13% reduction in cumulative infections) and 20-24 year-olds (22% of cumulative infections). ART, VMMC, and increasing AFS acted additively to reduce HIV incidence in AGYW, with little redundancy when combined. Interpretation: Our results provide strong support for maintaining both the protective changes in sexual behaviours and effective biomedical interventions to sustain continued reductions in HIV incidence among AGYW.

  PublisherOA PDFDOI

• The changing cost‐effectiveness of primary HIV prevention: simple calculations of direct effects

  Journal of the International AIDS Society · 2025-05-01 · 1 citations

  articleOpen accessSenior author

  INTRODUCTION: Over the course of the HIV pandemic, prevention and treatment interventions have reduced HIV incidence, but there is still scope for new prevention tools to further control HIV. Studies of the cost-effectiveness of HIV prevention tools are often done using detailed, "transmission-aware" models, but there is a role for simpler analyses. DISCUSSION: We present equations to calculate the cost-effectiveness, budget impact and epidemiological impact of HIV prevention interventions including equations allowing for multiple interventions and heterogeneity in risk across populations. As HIV incidence declines, the number needed to cover to prevent one HIV acquisition increases. Along with the benefits of averting HIV acquisitions, the cost-effectiveness of HIV prevention interventions is driven by incidence, along with efficacy, duration and costs of the intervention. The budget impact is driven by cost, size of the population and coverage achieved, and impact is determined by the effective coverage of interventions. HIV incidence has declined in sub-Saharan Africa, making primary HIV prevention less cost-effective and decreasing the price at which new prevention products provide value. Heterogeneity in risk could in theory allow for focusing HIV prevention, but current screening tools do not appear to sufficiently differentiate risk in populations where they have been applied. The simple calculations shown here provide rough initial estimates that can be compared with more sophisticated transmission dynamic and health economic models. CONCLUSIONS: Simple equations show how the observed declines in HIV incidence in sub-Saharan Africa make primary prevention tools less cost-effective. If we require prevention to be more cost-effective, either we need primary prevention tools to be used disproportionately by those most at risk of acquiring HIV, or they need to be less expensive.

  PublisherOA PDFDOI

• The Effects of Reductions in United States Foreign Assistance on Global Health

  SSRN Electronic Journal · 2025-01-01 · 21 citations

  preprintOpen access
  PublisherDOI

• Simple calculations of direct impact for the initial assessment of the value of primary HIV prevention interventions

  medRxiv · 2024-07-14

  preprintOpen accessSenior author

  Abstract Introduction Over the course of the HIV pandemic prevention and treatment interventions have reduced HIV incidence but there is still scope for new prevention tools to further control HIV. Studies of the transmission dynamics and cost effectiveness of HIV prevention tools are often done using detailed complex models but there is a role for simpler earlier analyses. Methods Equations are defined to calculate the cost effectiveness, budget impact, and epidemiological impact of HIV prevention interventions including equations allowing for multiple interventions and heterogeneity in risk across populations. An efficiency ratio of primary HIV prevention and IV treatment as prevention is defined. Results As HIV incidence declines the number needed to treat to prevent one HIV infection increases. The cost effectiveness of HIV is driven by incidence, along with efficacy, duration, and costs of the intervention. The budget impact is driven by cost, size of the population and coverage achieved, and impact is determined by the effective coverage of interventions. Heterogeneity in risk could in theory allow for targeting primary HIV prevention but current screening tools do not appear to sufficiently differentiate risk in populations where they have been applied. Discussion Simple calculations provide a tool to readily assess the cost-effectiveness, impact, and budget impact of HIV prevention interventions and can include heterogeneities in risk of HIV acquisition. These calculations provide rough initial estimates that can be compared with more sophisticated transmission dynamic and health economic models. Conclusion HIV incidence is declining making primary prevention tools less cost effective. If we require prevention to be more cost effective either we need to target primary prevention tools or they need to be less expensive. Simple equations allow for an exploration of the cost effectiveness of HIV interventions but the sensitivity of results to assumptions needs to be tested by comparison with transmission dynamic models.

  PublisherOA PDFDOI

• The HIV response beyond 2030: preparing for decades of sustained HIV epidemic control in eastern and southern Africa

  The Lancet · 2024-05-20 · 10 citations

  article1st authorCorresponding
  PublisherDOI

Frequent coauthors

• Anna Bershteyn

  New York University

  72 shared

• Frank Tanser

  University of KwaZulu-Natal

  36 shared

• Ann Duerr

  Fred Hutch Cancer Center

  21 shared

• Moses R. Kamya

  Makerere University

  20 shared

• Till Bärnighausen

  University Hospital Heidelberg

  20 shared

• Monisha Sharma

  17 shared

• Sarah Ssali

  Makerere University

  16 shared

• Patrick Eyul

  Infectious Diseases Research Collaboration

  15 shared