HIV prevalence, risk behaviour, and treatment and prevention cascade outcomes among cisgender men, transgender women, and transgender men who sell sex in Zimbabwe: a cross-sectional analysis of programme data

BACKGROUND

There is a paucity of evidence on HIV vulnerabilities and service engagements among people who sell sex in sub-Saharan Africa and identify as cisgender men, transgender women, or transgender men. We aimed to describe sexual risk behaviours, HIV prevalence, and access to HIV services among cisgender men, transgender women, and transgender men who sell sex in Zimbabwe.

METHODS

We did a cross-sectional analysis of routine programme data that were collected between July 1, 2018, and June 30, 2020, from cisgender men who sell sex, transgender women who sell sex, and transgender men who sell sex, as part of accessing sexual and reproductive health and HIV services provided through the Sisters with a Voice programme, at 31 sites across Zimbabwe. All people who sell sex reached by the programme had routine data collected, including routine HIV testing, and were referred using a network of peer educators. Sexual risk behaviours, HIV prevalence, and HIV services uptake during the period from July, 2018, to June, 2020, were analysed through descriptive statistics by gender group.

FINDINGS

A total of 1003 people who sell sex were included in our analysis: 423 (42·2%) cisgender men, 343 (34·2%) transgender women, and 237 (23·6%) transgender men. Age-standardised HIV prevalence estimates were 26·2% (95% CI 22·0-30·7) among cisgender men, 39·4% (34·1-44·9) among transgender women, and 38·4% (32·1-45·0) among transgender men. Among people living with HIV, 66·0% (95% CI 55·7-75·3) of cisgender men, 74·8% (65·8-82·4) of transgender women, and 70·2% (59·3-79·7) of transgender men knew their HIV status, and 15·5% (8·9-24·2), 15·7% (9·5-23·6), and 11·9% (5·9-20·8) were on antiretroviral therapy, respectively. Self-reported condom use was consistently low across gender groups, ranging from 26% (95% CI 22-32) for anal sex among transgender women to 32% (27-37) for vaginal sex among cisgender men.

INTERPRETATION

These unique data show that people who sell sex and identify as cisgender men, transgender women, or transgender men in sub-Saharan Africa have high HIV prevalences and risk of infection, with alarmingly low access to HIV prevention, testing, and treatment services. There is an urgent need for people-centred HIV interventions for these high-risk groups and for more inclusive HIV policies and research to ensure we truly attain universal access for all.

FUNDING

Aidsfonds Netherlands.

HIV prevalence among men who have sex with men, transgender women and cisgender male sex workers in sub-Saharan Africa: a systematic review and meta-analysis

INTRODUCTION

Developing effective targets, policies and services for key populations requires estimations of population sizes and HIV prevalence across countries and regions. We estimated the relative and absolute HIV prevalence among men who have sex with men (MSM), transgender women and men, and male and transgender sex workers (MSW and TGSW) in sub-Saharan African countries using peer-reviewed literature.

METHODS

We performed a systematic review of peer-reviewed studies assessing HIV prevalence in MSM, transgender women and men, MSW and TGSW in sub-Saharan Africa between 2010 and 2021, following PRISMA guidelines. We searched Embase, Medline Epub, Africa Index Medicus, Africa Journal Online, Web of Science and Google Scholar. We calculated HIV prevalence ratios (PRs) between the study prevalence, and the geospatial-, sex, time and age-matched general population prevalence. We extrapolated results for MSM and transgender women to estimate HIV prevalence and the number living with HIV for each country in sub-Saharan Africa using pooled review results, and regression approximations for countries with no peer-reviewed data.

RESULTS AND DISCUSSION

We found 44 articles assessing HIV prevalence in MSM, 10 in transgender women, five in MSW and zero in transgender men and TGSW. Prevalence among MSM and transgender women was significantly higher compared to the general population: PRs of 11.3 [CI: 9.9-12.9] for MSM and 8.1 [CI: 6.9-9.6] for transgender women in Western and Central Africa, and, respectively, 1.9 [CI: 1.7-2.0] and 2.1 [CI: 1.9-2.4] in Eastern and Southern Africa. Prevalence among MSW was significantly higher in both Nigeria (PR: 12.4 [CI: 7.3-21.0]) and Kenya (PR: 8.6 [CI: 4.6-15.6]). Extrapolating our findings for MSM and transgender women resulted in an estimated HIV prevalence of 15% or higher for about 60% of all sub-Saharan African countries for MSM, and for all but two countries for transgender women.

CONCLUSIONS

HIV prevalence among MSM and transgender women throughout sub-Saharan Africa is alarmingly high. This high prevalence, coupled with the specific risks and vulnerabilities faced by these populations, highlights the urgent need for risk-group-tailored prevention and treatment interventions across the sub-continent. There is a clear gap in knowledge on HIV prevalence among transgender men, MSW and TGSW in sub-Saharan Africa.

Rapid elimination of cervical cancer while maintaining the harms and benefits ratio of cervical cancer screening: a modelling study

BACKGROUND

Human papillomavirus (HPV) vaccination and intensifying screening expedite cervical cancer (CC) elimination, yet also deteriorate the balance between harms and benefits of screening. We aimed to find screening strategies that eliminate CC rapidly but maintain an acceptable harms-benefits ratio of screening.

METHODS

Two microsimulation models (STDSIM and MISCAN) were applied to simulate HPV transmission and CC screening for the Dutch female population between 2022 and 2100. We estimated the CC elimination year and harms-benefits ratios of screening for 228 unique scenarios varying in vaccination (coverage and vaccine type) and screening (coverage and number of lifetime invitations in vaccinated cohorts). The acceptable harms-benefits ratio was defined as the number of women needed to refer (NNR) to prevent one CC death under the current programme for unvaccinated cohorts (82.17).

RESULTS

Under current vaccination conditions (bivalent vaccine, 55% coverage in girls, 27.5% coverage in boys), maintaining current screening conditions is projected to eliminate CC by 2042, but increases the present NNR with 41%. Reducing the number of lifetime screens from presently five to three and increasing screening coverage (61% to 70%) would prevent an increase in harms and only delay elimination by 1 year. Scaling vaccination coverage to 90% in boys and girls with the nonavalent vaccine is estimated to eliminate CC by 2040 under current screening conditions, but exceeds the acceptable NNR with 23%. Here, changing from five to two lifetime screens would keep the NNR acceptable without delaying CC elimination.

CONCLUSIONS

De-intensifying CC screening in vaccinated cohorts leads to little or no delay in CC elimination while it substantially reduces the harms of screening. Therefore, de-intensifying CC screening in vaccinated cohorts should be considered to ensure acceptable harms-benefits ratios on the road to CC elimination.

No increased HIV risk in general population near sex work sites: a nationally representative cross-sectional study in Zimbabwe

Objectives

Sex work sites have been hypothesised to be at the root of the observed heterogeneity in HIV prevalence in sub‐Saharan Africa. We determined if proximity to sex work sites is associated with HIV prevalence among the general population in Zimbabwe, a country with one of the highest HIV prevalence in the world.

Methods

In this cross‐sectional study we use a unique combination of nationally representative geolocated individual‐level data from 16,121 adults (age 15–49 years) from 400 sample locations and the locations of 55 sex work sites throughout Zimbabwe; covering an estimated 95% of all female sex workers (FSWs). We calculated the shortest distance by road from each survey sample location to the nearest sex work site, for all sites and by type of sex work site, and conducted univariate and multivariate multilevel logistic regressions to determine the association between distance to sex work sites and HIV seropositivity, controlling for age, sex, male circumcision status, number of lifetime sex partners, being a FSW client or being a stable partner of an FSW client.

Results

We found no significant association between HIV seroprevalence and proximity to the nearest sex work site among the general population in Zimbabwe, regardless of which type of site is closest (city site adjusted odds ratio [aOR] 1.010 [95% confidence interval {CI} 0.992–1.028]; economic growth point site aOR 0.982 [95% CI 0.962–1.002]; international site aOR 0.995 [95% CI 0.979–1.012]; seasonal site aOR 0.987 [95% CI 0.968–1.006] and transport site aOR 1.007 [95% CI 0.987–1.028]). Individual‐level indicators of sex work were significantly associated with HIV seropositivity: being an FSW client (aOR 1.445 [95% CI 1.188–1.745]); nine or more partners versus having one to three lifetime partners (aOR 2.072 [95% CI 1.654–2.596]).

Conclusions

Sex work sites do not seem to directly affect HIV prevalence among the general population in surrounding areas. Prevention and control interventions for HIV at these locations should primarily focus on sex workers and their clients, with special emphasis on including and retaining mobile sex workers and clients into services.

Evidence-based policymaking when evidence is incomplete: The case of HIV programme integration

Jan Hontelez and co-authors discuss the use of different types of evidence to inform HIV program integration.

Integrating HIV services and other health services: A systematic review and meta-analysis

BACKGROUND

Integration of HIV services with other health services has been proposed as an important strategy to boost the sustainability of the global HIV response. We conducted a systematic and comprehensive synthesis of the existing scientific evidence on the impact of service integration on the HIV care cascade, health outcomes, and cost-effectiveness.

METHODS AND FINDINGS

We reviewed the global quantitative empirical evidence on integration published between 1 January 2010 and 10 September 2021. We included experimental and observational studies that featured both an integration intervention and a comparator in our review. Of the 7,118 unique peer-reviewed English-language studies that our search algorithm identified, 114 met all of our selection criteria for data extraction. Most of the studies (90) were conducted in sub-Saharan Africa, primarily in East Africa (55) and Southern Africa (24). The most common forms of integration were (i) HIV testing and counselling added to non-HIV services and (ii) non-HIV services added to antiretroviral therapy (ART). The most commonly integrated non-HIV services were maternal and child healthcare, tuberculosis testing and treatment, primary healthcare, family planning, and sexual and reproductive health services. Values for HIV care cascade outcomes tended to be better in integrated services: uptake of HIV testing and counselling (pooled risk ratio [RR] across 37 studies: 1.67 [95% CI 1.41-1.99], p < 0.001), ART initiation coverage (pooled RR across 19 studies: 1.42 [95% CI 1.16-1.75], p = 0.002), time until ART initiation (pooled RR across 5 studies: 0.45 [95% CI 0.20-1.00], p = 0.050), retention in HIV care (pooled RR across 19 studies: 1.68 [95% CI 1.05-2.69], p = 0.031), and viral suppression (pooled RR across 9 studies: 1.19 [95% CI 1.03-1.37], p = 0.025). Also, treatment success for non-HIV-related diseases and conditions and the uptake of non-HIV services were commonly higher in integrated services. We did not find any significant differences for the following outcomes in our meta-analyses: HIV testing yield, ART adherence, HIV-free survival among infants, and HIV and non-HIV mortality. We could not conduct meta-analyses for several outcomes (HIV infections averted, costs, and cost-effectiveness), because our systematic review did not identify sufficient poolable studies. Study limitations included possible publication bias of studies with significant or favourable findings and comparatively weak evidence from some world regions and on integration of services for key populations in the HIV response.

CONCLUSIONS

Integration of HIV services and other health services tends to improve health and health systems outcomes. Despite some scientific limitations, the global evidence shows that service integration can be a valuable strategy to boost the sustainability of the HIV response and contribute to the goal of 'ending AIDS by 2030', while simultaneously supporting progress towards universal health coverage.

The Differential Risk of Cervical Cancer in HPV-Vaccinated and -Unvaccinated Women: A Mathematical Modeling Study

BACKGROUND

With increased uptake of vaccination against human papillomavirus (HPV), protection against cervical cancer will also increase for unvaccinated women, due to herd immunity. Still, the differential risk between vaccinated and unvaccinated women might warrant a vaccination-status-screening approach. To understand the potential value of stratified screening protocols, we estimated the risk differentials in HPV and cervical cancer between vaccinated and unvaccinated women.

METHODS

We used STDSIM, an individual-based model of HPV transmission and control, to estimate the HPV prevalence reduction over time, after introduction of HPV vaccination. We simulated scenarios of bivalent or nonavalent vaccination in females-only or females and males, at 20% coverage increments. We estimated relative HPV-type-specific prevalence reduction compared with a no-vaccination counterfactual and then estimated the age-specific cervical cancer risk by vaccination status.

RESULTS

The relative cervical cancer risk for unvaccinated compared with vaccinated women ranged from 1.7 (bivalent vaccine for females and males; 80% coverage) to 10.8 (nonavalent vaccine for females-only; 20% coverage). Under 60% vaccination coverage, which is a representative coverage for several western countries, including the United States, the relative risk (RR) varies between 2.2 (bivalent vaccine for females and males) and 9.2 (nonavalent vaccine for females).

CONCLUSIONS

We found large cervical cancer risk differences between vaccinated and unvaccinated women. In general, our model shows that the RR is higher in lower vaccine coverages, using the nonavalent vaccine, and when vaccinating females only.

IMPACT

To avoid a disbalance in harms and benefits between vaccinated and unvaccinated women, vaccination-based screening needs serious consideration.

Epidemiological And Health Systems Implications Of Evolving HIV And Hypertension In South Africa And Kenya

Health systems in sub-Saharan Africa are facing an ongoing HIV epidemic and increasing burden of noncommunicable disease. With the focus shifting to the development of comprehensive primary health care and chronic disease treatment, multidisease modeling is integral to estimating future health care needs. We extended an established agent-based model of HIV transmission to include hypertension in two rural settings: KwaZulu-Natal, South Africa, and western Kenya. We estimated that from 2018 to 2028 hypertension prevalence would increase from 40 percent to 46 percent in KwaZulu-Natal and from 29 percent to 35 percent in western Kenya, while HIV prevalence is stabilizing and predicted to decrease. As the health system burden in sub-Saharan Africa is changing, innovative chronic disease treatment and the broadening of successful programs, such as integrated HIV and noncommunicable disease care, are necessary to reach universal health care coverage.

Mapping and characterising areas with high levels of HIV transmission in sub-Saharan Africa: A geospatial analysis of national survey data

BACKGROUND

In the generalised epidemics of sub-Saharan Africa (SSA), human immunodeficiency virus (HIV) prevalence shows patterns of clustered micro-epidemics. We mapped and characterised these high-prevalence areas for young adults (15-29 years of age), as a proxy for areas with high levels of transmission, for 7 countries in Eastern and Southern Africa: Kenya, Malawi, Mozambique, Tanzania, Uganda, Zambia, and Zimbabwe.

METHODS AND FINDINGS

We used geolocated survey data from the most recent United States Agency for International Development (USAID) demographic and health surveys (DHSs) and AIDS indicator surveys (AISs) (collected between 2008-2009 and 2015-2016), which included about 113,000 adults-of which there were about 53,000 young adults (27,000 women, 28,000 men)-from over 3,500 sample locations. First, ordinary kriging was applied to predict HIV prevalence at unmeasured locations. Second, we explored to what extent behavioural, socioeconomic, and environmental factors explain HIV prevalence at the individual- and sample-location level, by developing a series of multilevel multivariable logistic regression models and geospatially visualising unexplained model heterogeneity. National-level HIV prevalence for young adults ranged from 2.2% in Tanzania to 7.7% in Mozambique. However, at the subnational level, we found areas with prevalence among young adults as high as 11% or 15% alternating with areas with prevalence between 0% and 2%, suggesting the existence of areas with high levels of transmission Overall, 15.6% of heterogeneity could be explained by an interplay of known behavioural, socioeconomic, and environmental factors. Maps of the interpolated random effect estimates show that environmental variables, representing indicators of economic activity, were most powerful in explaining high-prevalence areas. Main study limitations were the inability to infer causality due to the cross-sectional nature of the surveys and the likely under-sampling of key populations in the surveys.

CONCLUSIONS

We found that, among young adults, micro-epidemics of relatively high HIV prevalence alternate with areas of very low prevalence, clearly illustrating the existence of areas with high levels of transmission. These areas are partially characterised by high economic activity, relatively high socioeconomic status, and risky sexual behaviour. Localised HIV prevention interventions specifically tailored to the populations at risk will be essential to curb transmission. More fine-scale geospatial mapping of key populations,-such as sex workers and migrant populations-could help us further understand the drivers of these areas with high levels of transmission and help us determine how they fuel the generalised epidemics in SSA.

HIV Treatment Substantially Decreases Hospitalization Rates: Evidence From Rural South Africa

The effect of HIV treatment on hospitalization rates for HIV-infected people has never been established. We quantified this effect in a rural South African community for the period 2009-13. We linked clinical data on HIV treatment start dates for more than 2,000 patients receiving care in the public-sector treatment program with five years of longitudinal data on self-reported hospitalizations from a community-based population cohort of more than 100,000 adults. Hospitalization rates peaked during the first year of treatment and were about five times higher, compared to hospitalization rates after four years on treatment. Earlier treatment initiation could save more than US$300,000 per 1,000 patients over the first four years of HIV treatment, freeing up scarce resources. Future studies on the cost-effectiveness of HIV treatment should include these effects.

Socioeconomic benefit to individuals of achieving 2020 targets for four neglected tropical diseases controlled/eliminated by innovative and intensified disease management: Human African trypanosomiasis, leprosy, visceral leishmaniasis, Chagas disease

BACKGROUND

The control or elimination of neglected tropical diseases (NTDs) has targets defined by the WHO for 2020, reinforced by the 2012 London Declaration. We estimated the economic impact to individuals of meeting these targets for human African trypanosomiasis, leprosy, visceral leishmaniasis and Chagas disease, NTDs controlled or eliminated by innovative and intensified disease management (IDM).

METHODS

A systematic literature review identified information on productivity loss and out-of-pocket payments (OPPs) related to these NTDs, which were combined with projections of the number of people suffering from each NTD, country and year for 2011-2020 and 2021-2030. The ideal scenario in which the WHO's 2020 targets are met was compared with a counterfactual scenario that assumed the situation of 1990 stayed unaltered. Economic benefit equaled the difference between the two scenarios. Values are reported in 2005 US$, purchasing power parity-adjusted, discounted at 3% per annum from 2010. Probabilistic sensitivity analyses were used to quantify the degree of uncertainty around the base-case impact estimate.

RESULTS

The total global productivity gained for the four IDM-NTDs was I$ 23.1 (I$ 15.9 -I$ 34.0) billion in 2011-2020 and I$ 35.9 (I$ 25.0 -I$ 51.9) billion in 2021-2030 (2.5th and 97.5th percentiles in brackets), corresponding to US$ 10.7 billion (US$ 7.4 -US$ 15.7) and US$ 16.6 billion (US$ 11.6 -US$ 24.0). Reduction in OPPs was I$ 14 billion (US$ 6.7 billion) and I$ 18 billion (US$ 10.4 billion) for the same periods.

CONCLUSIONS

We faced important limitations to our work, such as finding no OPPs for leprosy. We had to combine limited data from various sources, heterogeneous background, and of variable quality. Nevertheless, based on conservative assumptions and subsequent uncertainty analyses, we estimate that the benefits of achieving the targets are considerable. Under plausible scenarios, the economic benefits far exceed the necessary investments by endemic country governments and their development partners. Given the higher frequency of NTDs among the poorest households, these investments represent good value for money in the effort to improve well-being, distribute the world's prosperity more equitably and reduce inequity.

Behavioural disinhibition in the general population during the antiretroviral therapy roll-out in Sub-Saharan Africa: systematic review and meta-analysis

OBJECTIVES

Improved life expectancy and reduced transmission probabilities due to ART may result in behavioural disinhibition - that is an increase in sexual risk behaviour in response to a perceived lower risk of HIV. We examined trends in sexual risk behaviour in the general population of sub-Saharan African countries 1999-2015.

METHODS

We systematically reviewed scientific literature of sexual behaviour and reviewed trends in Demographic and Health Surveys. A meta-analysis on four indicators of sexual risk behaviour was performed: unprotected sex, multiple sexual partners, commercial sex and prevalence of sexually transmitted infections.

RESULTS

Only two peer-reviewed studies met our inclusion criteria, while our review of DHS data spanned 18 countries and 16 years (1999-2015). We found conflicting trends in sexual risk behaviour. Reported unprotected sex decreased consistently across the 18 countries, for both sexes. In contrast, reporting multiple partners was decreasing over the period 1999 to the mid-2000s, yet has been consistently increasing thereafter. Similar trends were found for reported sexually transmitted infections and commercial sex (men only).

CONCLUSIONS

In conclusion, we found no clear evidence of behavioural disinhibition due to expanded access to ART in sub-Saharan Africa. Substantial increases in condom use coincided with increases in reported multiple partners, commercial sex and sexually transmitted infections, especially during the period of ART scale-up. Further research is needed into how these changes might affect HIV transmission.

Evidence for scaling up HIV treatment in sub-Saharan Africa: A call for incorporating health system constraints

Jan Hontelez and colleagues argue that the cost-effectiveness studies of HIV treatment scale-up need to include health system constraints to be more informative.

The Socioeconomic Benefit to Individuals of Achieving the 2020 Targets for Five Preventive Chemotherapy Neglected Tropical Diseases

BACKGROUND

Lymphatic filariasis (LF), onchocerciasis, schistosomiasis, soil-transmitted helminths (STH) and trachoma represent the five most prevalent neglected tropical diseases (NTDs). They can be controlled or eliminated by means of safe and cost-effective interventions delivered through programs of Mass Drug Administration (MDA)-also named Preventive Chemotherapy (PCT). The WHO defined targets for NTD control/elimination by 2020, reinforced by the 2012 London Declaration, which, if achieved, would result in dramatic health gains. We estimated the potential economic benefit of achieving these targets, focusing specifically on productivity and out-of-pocket payments.

METHODS

Productivity loss was calculated by combining disease frequency with productivity loss from the disease, from the perspective of affected individuals. Productivity gain was calculated by deducting the total loss expected in the target achievement scenario from the loss in a counterfactual scenario where it was assumed the pre-intervention situation in 1990 regarding NTDs would continue unabated until 2030. Economic benefits from out-of-pocket payments (OPPs) were calculated similarly. Benefits are reported in 2005 US$ (purchasing power parity-adjusted and discounted at 3% per annum from 2010). Sensitivity analyses were used to assess the influence of changes in input parameters.

RESULTS

The economic benefit from productivity gain was estimated to be I$251 billion in 2011-2020 and I$313 billion in 2021-2030, considerably greater than the total OPPs averted of I$0.72 billion and I$0.96 billion in the same periods. The net benefit is expected to be US$ 27.4 and US$ 42.8 for every dollar invested during the same periods. Impact varies between NTDs and regions, since it is determined by disease prevalence and extent of disease-related productivity loss.

CONCLUSION

Achieving the PCT-NTD targets for 2020 will yield significant economic benefits to affected individuals. Despite large uncertainty, these benefits far exceed the investment required by governments and their development partners within all reasonable scenarios. Given the concentration of the NTDs among the poorest households, these investments represent good value for money in efforts to share the world's prosperity and reduce inequity.

Population-level impact, herd immunity, and elimination after human papillomavirus vaccination: a systematic review and meta-analysis of predictions from transmission-dynamic models

BACKGROUND

Modelling studies have been widely used to inform human papillomavirus (HPV) vaccination policy decisions; however, many models exist and it is not known whether they produce consistent predictions of population-level effectiveness and herd effects. We did a systematic review and meta-analysis of model predictions of the long-term population-level effectiveness of vaccination against HPV 16, 18, 6, and 11 infection in women and men, to examine the variability in predicted herd effects, incremental benefit of vaccinating boys, and potential for HPV-vaccine-type elimination.

METHODS

We searched MEDLINE and Embase for transmission-dynamic modelling studies published between Jan 1, 2009, and April 28, 2015, that predicted the population-level impact of vaccination on HPV 6, 11, 16, and 18 infections in high-income countries. We contacted authors to determine whether they were willing to produce new predictions for standardised scenarios. Strategies investigated were girls-only vaccination and girls and boys vaccination at age 12 years. Base-case vaccine characteristics were 100% efficacy and lifetime protection. We did sensitivity analyses by varying vaccination coverage, vaccine efficacy, and duration of protection. For all scenarios we pooled model predictions of relative reductions in HPV prevalence (RRprev) over time after vaccination and summarised results using the median and 10th and 90th percentiles (80% uncertainty intervals [UI]).

FINDINGS

16 of 19 eligible models from ten high-income countries provided predictions. Under base-case assumptions, 40% vaccination coverage and girls-only vaccination, the RRprev of HPV 16 among women and men was 0·53 (80% UI 0·46-0·68) and 0·36 (0·28-0·61), respectively, after 70 years. With 80% girls-only vaccination coverage, the RRprev of HPV 16 among women and men was 0·93 (0·90-1·00) and 0·83 (0·75-1·00), respectively. Vaccinating boys in addition to girls increased the RRprev of HPV 16 among women and men by 0·18 (0·13-0·32) and 0·35 (0·27-0·39) for 40% coverage, and 0·07 (0·00-0·10) and 0·16 (0·01-0·25) for 80% coverage, respectively. The RRprev were greater for HPV 6, 11, and 18 than for HPV 16 for all scenarios investigated. Finally at 80% coverage, most models predicted that girls and boys vaccination would eliminate HPV 6, 11, 16, and 18, with a median RRprev of 1·00 for women and men for all four HPV types. Variability in pooled findings was low, but increased with lower vaccination coverage and shorter vaccine protection (from lifetime to 20 years).

INTERPRETATION

Although HPV models differ in structure, data used for calibration, and settings, our population-level predictions were generally concordant and suggest that strong herd effects are expected from vaccinating girls only, even with coverage as low as 20%. Elimination of HPV 16, 18, 6, and 11 is possible if 80% coverage in girls and boys is reached and if high vaccine efficacy is maintained over time.

FUNDING

Canadian Institutes of Health Research.

The Effect of Antiretroviral Treatment on Health Care Utilization in Rural South Africa: A Population-Based Cohort Study

Background

The effect of the rapid scale-up of vertical antiretroviral treatment (ART) programs for HIV in sub-Saharan Africa on the overall health system is under intense debate. Some have argued that these programs have reduced access for people suffering from diseases unrelated to HIV because ART programs have drained human and physical resources from other parts of the health system; others have claimed that the investments through ART programs have strengthened the general health system and the population health impacts of ART have freed up health care capacity for the treatment of diseases that are not related to HIV. To establish the population-level impact of ART programs on health care utilization in the public-sector health system, we compared trends in health care utilization among HIV-infected people receiving and not receiving ART with HIV-uninfected people during a period of rapid ART scale-up.

Methods and Findings

We used data from the Wellcome Trust Africa Centre for Population Health, which annually elicited information on health care utilization from all surveillance participants over the period 2009–2012 (N = 32,319). We determined trends in hospitalization, and public-sector and private-sector primary health care (PHC) clinic visits for HIV-infected and -uninfected people over a time period of rapid ART scale-up (2009–2012) in this community. We regressed health care utilization on HIV status and ART status in different calendar years, controlling for sex, age, and area of residence. The proportion of people who reported to have visited a public-sector primary health care (PHC) clinic in the last 6 months increased significantly over the period 2009–2012, for both HIV-infected people (from 59% to 67%; p<0.001), and HIV-uninfected people (from 41% to 47%; p<0.001). In contrast, the proportion of HIV-infected people visiting a private-sector PHC clinic declined from 22% to 12% (p<0.001) and hospitalization rates declined from 128 to 82 per 1000 PY (p<0.001). For HIV-uninfected people, the proportion visiting a private-sector PHC clinic declined from 16% to 9%, and hospitalization rates declined from 78 to 44 per 1000 PY (p<0.001). After controlling for potential confounding factors, all trends remained of similar magnitude and significance.

Conclusions

Our results indicate that the ART scale-up in this high HIV prevalence community has shifted health care utilization from hospitals and private-sector primary care to public-sector primary care. Remarkably, this shift is observed for both HIV-infected and -uninfected populations, supporting and extending hypotheses of ‘therapeutic citizenship’ whereby HIV-infected patients receiving ART facilitate primary care access for family and community members. One explanation of our findings is that ART has improved the capacity or quality of primary care in this community and, as a consequence, increasingly met overall health care needs at the primary care level rather than at the secondary level. Future research needs to confirm this causal interpretation of our findings using qualitative work to understand causal mechanisms or quasi-experimental quantitative studies to increase the strength of causal inference.

Public Health Benefits of Routine Human Papillomavirus Vaccination for Adults in the Netherlands: A Mathematical Modeling Study

BACKGROUND

Expanding routine human papillomavirus (HPV) vaccination to adults could be an effective strategy to improve prevention of HPV infection and cervical cancer.

METHODS

We evaluated the following adult vaccination strategies for women only and for both women and men in addition to the current girls-only vaccination program in the Netherlands, using the established STDSIM microsimulation model: one-time mass campaign, vaccination at the first cervical cancer screening visit, vaccination at sexual health clinics, and combinations of these strategies.

RESULTS

The estimated impact of expanding routine vaccination to adult women is modest, with the largest incremental reductions in the incidence of HPV infection occurring when offering vaccination both at the cervical cancer screening visit and during sexually transmitted infection (STI) consultations (about 20% lower after 50 years for both HPV-16 and HPV-18). Adding male vaccination during STI consultations leads to more-substantial incidence reductions: 63% for HPV-16 and 84% for HPV-18. The incremental number needed to vaccinate among women is 5.48, compared with 0.90 for the current vaccination program.

CONCLUSIONS

Offering vaccination to adults, especially at cervical cancer screening visits (for women) and during STI consultations (for both sexes), would substantially reduce HPV incidence and would be an efficient policy option to improve HPV prevention and subsequently avert cervical and possibly male HPV-related cancers.

Concerted Efforts to Control or Eliminate Neglected Tropical Diseases: How Much Health Will Be Gained?

Background

The London Declaration (2012) was formulated to support and focus the control and elimination of ten neglected tropical diseases (NTDs), with targets for 2020 as formulated by the WHO Roadmap. Five NTDs (lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths and trachoma) are to be controlled by preventive chemotherapy (PCT), and four (Chagas’ disease, human African trypanosomiasis, leprosy and visceral leishmaniasis) by innovative and intensified disease management (IDM). Guinea worm, virtually eradicated, is not considered here. We aim to estimate the global health impact of meeting these targets in terms of averted morbidity, mortality, and disability adjusted life years (DALYs).

Methods

The Global Burden of Disease (GBD) 2010 study provides prevalence and burden estimates for all nine NTDs in 1990 and 2010, by country, age and sex, which were taken as the basis for our calculations. Estimates for other years were obtained by interpolating between 1990 (or the start-year of large-scale control efforts) and 2010, and further extrapolating until 2030, such that the 2020 targets were met. The NTD disease manifestations considered in the GBD study were analyzed as either reversible or irreversible. Health impacts were assessed by comparing the results of achieving the targets with the counterfactual, construed as the health burden had the 1990 (or 2010 if higher) situation continued unabated.

Principle Findings/Conclusions

Our calculations show that meeting the targets will lead to about 600 million averted DALYs in the period 2011–2030, nearly equally distributed between PCT and IDM-NTDs, with the health gain amongst PCT-NTDs mostly (96%) due to averted disability and amongst IDM-NTDs largely (95%) from averted mortality. These health gains include about 150 million averted irreversible disease manifestations (e.g. blindness) and 5 million averted deaths. Control of soil-transmitted helminths accounts for one third of all averted DALYs. We conclude that the projected health impact of the London Declaration justifies the required efforts.

Neglected tropical diseases (NTDs) are a group of infectious diseases that occur mostly in poor, warm countries. NTDs are caused by various bacteria and parasites, such as worms. They can either be cured or prevented through drugs and other interventions, such as control of insects that spread the infection. The London Declaration is a statement by various organizations, including the World Health Organization (WHO) and pharmaceutical companies that donate the necessary drugs. The declaration endorses targets for disease reductions by 2020, as recently formulated in the WHO Roadmap, to be achieved by rigorous application of available interventions. We explore how much health can be gained if these targets are indeed achieved. We estimate that in such case 5 million deaths can be averted before 2030 and also that huge reductions in ill-health and disability can be realized. Over the period 2011–2030, a total health gain would be accomplished of about 600 million disability adjusted life years (DALYs) averted. DALYs are a measure of disease burden, consisting of life years lost and years lived with disability. This enormous health gain seems to justify similar investments as for e.g. HIV or malaria control.

The role of acquired immunity in the spread of human papillomavirus (HPV): explorations with a microsimulation model

Background

Knowledge of the natural history of human papillomavirus (HPV), in particular the role of immunity, is crucial in estimating the (cost-) effectiveness of HPV vaccination and cervical cancer screening strategies, because naturally acquired immunity after clearing an infection may already protect part of the risk population against new HPV infections.

Methods

We used STDSIM, an established stochastic microsimulation model, quantified to the Netherlands. We explored different assumptions regarding the natural history of HPV-16 and HPV-18, and estimated the transmission probabilities and durations of acquired immunity necessary to reproduce age-specific prevalence.

Results

A model without acquired immunity cannot reproduce the age-specific patterns of HPV. Also, it is necessary to assume a high degree of individual variation in the duration of infection and acquired immunity. According to the model estimates, on average 20% of women are immune for HPV-16 and 15% for HPV-18. After an HPV-16 infection, 50% are immune for less than 1 year, whereas 20% exceed 30 years. For HPV-18, up to 12% of the individuals are immune for less than 1 year, and about 50% over 30 years. Almost half of all women will never acquire HPV-16 or HPV-18.

Conclusions

Acquired immunity likely plays a major role in HPV epidemiology, but its duration shows substantial variation. Combined with the lifetime risk, this explains to a large extent why many women will never develop cervical cancer.

Health benefits, costs, and cost-effectiveness of earlier eligibility for adult antiretroviral therapy and expanded treatment coverage: a combined analysis of 12 mathematical models

BACKGROUND

New WHO guidelines recommend ART initiation for HIV-positive persons with CD4 cell counts ≤500 cells/µL, a higher threshold than was previously recommended. Country decision makers must consider whether to further expand ART eligibility accordingly.

METHODS

We used multiple independent mathematical models in four settings-South Africa, Zambia, India, and Vietnam-to evaluate the potential health impact, costs, and cost-effectiveness of different adult ART eligibility criteria under scenarios of current and expanded treatment coverage, with results projected over 20 years. Analyses considered extending eligibility to include individuals with CD4 ≤500 cells/µL or all HIV-positive adults, compared to the previous recommendation of initiation with CD4 ≤350 cells/µL. We assessed costs from a health system perspective, and calculated the incremental cost per DALY averted ($/DALY) to compare competing strategies. Strategies were considered 'very cost-effective' if the $/DALY was less than the country's per capita gross domestic product (GDP; South Africa: $8040, Zambia: $1425, India: $1489, Vietnam: $1407) and 'cost-effective' if $/DALY was less than three times per capita GDP.

FINDINGS

In South Africa, the cost per DALY averted of extending ART eligibility to CD4 ≤500 cells/µL ranged from $237 to $1691/DALY compared to 2010 guidelines; in Zambia, expanded eligibility ranged from improving health outcomes while reducing costs (i.e. dominating current guidelines) to $749/DALY. Results were similar in scenarios with substantially expanded treatment access and for expanding eligibility to all HIV-positive adults. Expanding treatment coverage in the general population was therefore found to be cost-effective. In India, eligibility for all HIV-positive persons ranged from $131 to $241/DALY and in Vietnam eligibility for CD4 ≤500 cells/µL cost $290/DALY. In concentrated epidemics, expanded access among key populations was also cost-effective.

INTERPRETATION

Earlier ART eligibility is estimated to be very cost-effective in low- and middle-income settings, although these questions should be revisited as further information becomes available. Scaling-up ART should be considered among other high-priority health interventions competing for health budgets.

FUNDING

The Bill and Melinda Gates Foundation and World Health Organization.

The impact of antiretroviral treatment on the age composition of the HIV epidemic in sub-Saharan Africa

INTRODUCTION

Antiretroviral treatment (ART) coverage is rapidly expanding in sub-Saharan Africa (SSA). Based on the effect of ART on survival of HIV-infected people and HIV transmission, the age composition of the HIV epidemic in the region is expected to change in the coming decades. We quantify the change in the age composition of HIV-infected people in all countries in SSA.

METHODS

We used STDSIM, a stochastic microsimulation model, and developed an approach to represent HIV prevalence and treatment coverage in 43 countries in SSA, using publicly available data. We predict future trends in HIV prevalence and total number of HIV-infected people aged 15-49 years and 50 years or older for different ART coverage levels.

RESULTS

We show that, if treatment coverage continues to increase at present rates, the total number of HIV-infected people aged 50 years or older will nearly triple over the coming years: from 3.1 million in 2011 to 9.1 million in 2040, dramatically changing the age composition of the HIV epidemic in SSA. In 2011, about one in seven HIV-infected people was aged 50 years or older; in 2040, this ratio will be larger than one in four.

CONCLUSION

The HIV epidemic in SSA is rapidly ageing, implying changing needs and demands in many social sectors, including health, social care, and old-age pension systems. Health policymakers need to anticipate the impact of the changing HIV age composition in their planning for future capacity in these systems.

Costs, effects and cost-effectiveness of breast cancer control in Ghana

OBJECTIVE

Breast cancer control in Ghana is characterised by low awareness, late-stage treatment and poor survival. In settings with severely constrained health resources, there is a need to spend money wisely. To achieve this and to guide policy makers in their selection of interventions, this study systematically compares costs and effects of breast cancer control interventions in Ghana.

METHODS

We used a mathematical model to estimate costs and health effects of breast cancer interventions in Ghana from the healthcare perspective. Analyses were based on the WHO-CHOICE method, with health effects expressed in disability-adjusted life years (DALYs), costs in 2009 US dollars (US$) and cost-effectiveness ratios (CERs) in US$ per DALY averted. Analyses were based on local demographic, epidemiological and economic data, to the extent these data were available.

RESULTS

Biennial screening by clinical breast examination (CBE) of women aged 40-69 years, in combination with treatment of all stages, seems the most cost-effective intervention (costing $1299 per DALY averted). The intervention is also economically attractive according to international standards on cost-effectiveness. Mass media awareness raising (MAR) is the second best option (costing $1364 per DALY averted). Mammography screening of women of aged 40-69 years (costing $12,908 per DALY averted) cannot be considered cost-effective.

CONCLUSIONS

Both CBE screening and MAR seem economically attractive interventions. Given the uncertainty about the effectiveness of these interventions, only their phased introduction, carefully monitored and evaluated, is warranted. Moreover, their implementation is only meaningful if the capacity of basic cancer diagnostic, referral and treatment and possibly palliative services is simultaneously improved.

HIV treatment as prevention: systematic comparison of mathematical models of the potential impact of antiretroviral therapy on HIV incidence in South Africa

BACKGROUND

Many mathematical models have investigated the impact of expanding access to antiretroviral therapy (ART) on new HIV infections. Comparing results and conclusions across models is challenging because models have addressed slightly different questions and have reported different outcome metrics. This study compares the predictions of several mathematical models simulating the same ART intervention programmes to determine the extent to which models agree about the epidemiological impact of expanded ART.

METHODS AND FINDINGS

Twelve independent mathematical models evaluated a set of standardised ART intervention scenarios in South Africa and reported a common set of outputs. Intervention scenarios systematically varied the CD4 count threshold for treatment eligibility, access to treatment, and programme retention. For a scenario in which 80% of HIV-infected individuals start treatment on average 1 y after their CD4 count drops below 350 cells/µl and 85% remain on treatment after 3 y, the models projected that HIV incidence would be 35% to 54% lower 8 y after the introduction of ART, compared to a counterfactual scenario in which there is no ART. More variation existed in the estimated long-term (38 y) reductions in incidence. The impact of optimistic interventions including immediate ART initiation varied widely across models, maintaining substantial uncertainty about the theoretical prospect for elimination of HIV from the population using ART alone over the next four decades. The number of person-years of ART per infection averted over 8 y ranged between 5.8 and 18.7. Considering the actual scale-up of ART in South Africa, seven models estimated that current HIV incidence is 17% to 32% lower than it would have been in the absence of ART. Differences between model assumptions about CD4 decline and HIV transmissibility over the course of infection explained only a modest amount of the variation in model results.

CONCLUSIONS

Mathematical models evaluating the impact of ART vary substantially in structure, complexity, and parameter choices, but all suggest that ART, at high levels of access and with high adherence, has the potential to substantially reduce new HIV infections. There was broad agreement regarding the short-term epidemiologic impact of ambitious treatment scale-up, but more variation in longer term projections and in the efficiency with which treatment can reduce new infections. Differences between model predictions could not be explained by differences in model structure or parameterization that were hypothesized to affect intervention impact.

The impact of the new WHO antiretroviral treatment guidelines on HIV epidemic dynamics and cost in South Africa

Background

Since November 2009, WHO recommends that adults infected with HIV should initiate antiretroviral therapy (ART) at CD4+ cell counts of ≤350 cells/µl rather than ≤200 cells/µl. South Africa decided to adopt this strategy for pregnant and TB co-infected patients only. We estimated the impact of fully adopting the new WHO guidelines on HIV epidemic dynamics and associated costs.

Methods and Finding

We used an established model of the transmission and control of HIV in specified sexual networks and healthcare settings. We quantified the model to represent Hlabisa subdistrict, KwaZulu-Natal, South Africa. We predicted the HIV epidemic dynamics, number on ART and program costs under the new guidelines relative to treating patients at ≤200 cells/µl for the next 30 years. During the first five years, the new WHO treatment guidelines require about 7% extra annual investments, whereas 28% more patients receive treatment. Furthermore, there will be a more profound impact on HIV incidence, leading to relatively less annual costs after seven years. The resulting cumulative net costs reach a break-even point after on average 16 years.

Conclusions

Our study strengthens the WHO recommendation of starting ART at ≤350 cells/µl for all HIV-infected patients. Apart from the benefits associated with many life-years saved, a modest frontloading appears to lead to net savings within a limited time-horizon. This finding is robust to alternative assumptions and foreseeable changes in ART prices and effectiveness. Therefore, South Africa should aim at rapidly expanding its healthcare infrastructure to fully embrace the new WHO guidelines.

The potential impact of an HIV vaccine with limited protection on HIV incidence in Thailand: a modeling study

BACKGROUND

The RV144 trial on the ALVAC/AIDSVAX candidate HIV vaccine, carried out in Thailand, showed short-lived protection against infection.

METHODS

Using a deterministic compartmental model we explored the potential impact of this vaccine on heterosexual HIV transmission in Thailand. Both one-off vaccination strategies, as well as strategies with regular boosting, either annually or every two years, were explored. Both targeting the general adult population and prioritizing sex workers were modeled. The impact of risk compensation among high risk groups, as well as whether higher levels of safe sex in high risk groups could be an alternative to vaccination, was studied.

RESULTS

One-off vaccination campaigns had only transient effects, and boosting appears to be a key component of successful vaccination campaigns. Intensive vaccination campaigns may reduce HIV incidence by up to 75% after 10 years of vaccination. Targeting only sex workers has a smaller impact but has a more favorable cost-benefit ratio. Risk compensation has the potential of undoing much of the benefits of a vaccination program and may even increase incidence. In contrast, higher levels of safe sex among sex workers would provide a viable alternative to vaccinating this group.

DISCUSSION

The new vaccine holds promise for controlling HIV in Thailand and similar countries. In view of the short lived protection of the vaccine, regular boosting of immunity as well as avoidance of risk compensation are essential. Targeting sex workers would achieve the greatest reduction in incidence per vaccination and may be considered for expensive vaccines but its cost-effectiveness has to be compared to alternatives.

The potential impact of RV144-like vaccines in rural South Africa: a study using the STDSIM microsimulation model

BACKGROUND

The only successful HIV vaccine trial to date is the RV144 trial of the ALVAC/AIDSVAX vaccine in Thailand, which showed an overall incidence reduction of 31%. Most cases were prevented in the first year, suggesting a rapidly waning efficacy. Here, we predict the population level impact and cost-effectiveness of practical implementation of such a vaccine in a setting of a generalised epidemic with high HIV prevalence and incidence.

METHODS

We used STDSIM, an established individual-based microsimulation model, tailored to a rural South African area with a well-functioning HIV treatment and care programme. We estimated the impact of a single round of mass vaccination for everybody aged 15-49, as well as 5-year and 2-year re-vaccination strategies for young adults (aged 15-29). We calculated proportion of new infections prevented, cost-effectiveness indicators, and budget impact estimates of combined ART and vaccination programmes.

RESULTS

A single round of mass vaccination with a RV144-like vaccine will have a limited impact, preventing only 9% or 5% of new infections after 10 years at 60% and 30% coverage levels, respectively. Revaccination strategies are highly cost-effective if vaccine prices can be kept below 150 US$/vaccine for 2-year revaccination strategies, and below 200 US$/vaccine for 5-year revaccination strategies. Net cost-savings through reduced need for HIV treatment and care occur when vaccine prices are kept below 75 US$/vaccine. These results are sensitive to alternative assumptions on the underlying sexual network, background prevention interventions, and individual's propensity and consistency to participate in the vaccination campaign.

DISCUSSION

A modestly effective vaccine can be a cost-effective intervention in highly endemic settings. To predict the impact of vaccination strategies in other endemic situations, sufficient knowledge of the underlying sexual network, prevention and treatment interventions, and individual propensity and consistency to participate, is key. These issues are all best addressed in an individual-based microsimulation model.

Effectiveness and impact of hepatitis B virus vaccination of children with at least one parent born in a hepatitis B virus endemic country: an early assessment

OBJECTIVE

To determine the effectiveness and impact of the Dutch childhood hepatitis B virus (HBV) vaccination policy targeted at children with at least one parent born in a HBV endemic country.

METHODS

The Dutch vaccination registration database was used to determine vaccine coverage for HBV and DTP-IPV-Hib in the target population. HBV notifications were used to estimate the impact. The HBV incidence was determined in children aged 0-4 years and born after (2003-7) and before (1990-2002) the introduction of the HBV vaccination programme.

RESULTS

HBV vaccine coverage in the target population was 89.6% (96,186/107,338) in the period 2003-5. There were 37 notified acute infections in the pre-vaccination birth cohort 1990-2002 (incidence 2.9/10(6) person-years), compared with one in the post-vaccination birth cohort 2003-7 (incidence 0.3/10(6) person-years). The incidence rate ratio for the 2003-7 birth cohort compared with the 1990-2002 birth cohort was 0.12 (95% CI 0.02 to 0.87; p=0.04).

CONCLUSIONS

This paper shows that the incidence of HBV notifications in children born after the introduction of targeted childhood HBV vaccinations is lower compared with the incidence in children born before the start of this vaccination programme. Although this is consistent with a good HBV vaccine coverage, the interpretation is hampered by a change in case definition for notification in 1999. The results are of importance to policy makers in both The Netherlands and other countries that have a targeted HBV vaccination programme.