Impacts of Changing Sexual Behavior on Chlamydia and Gonorrhea Burden Among US High School Students, 2007 to 2017.

BACKGROUND: Rates of adolescent sexual activity have long been declining in the United States. We sought to estimate the number of cases of gonorrhea and chlamydia averted over 1 decade associated with these declines and associated costs saved. METHODS: We analyzed data from the Centers for Disease Control and Prevention's Youth Risk Behavior Survey of US high school students from 2007 to 2017 and combined it with epidemiological estimates drawn from the literature to parameterize a dynamic population transmission model. We compared transmissions from observed behavioral trends with a counterfactual scenario that assumed sexual behaviors from 2007 remained constant for 10 years. We calculated outcomes by age and for 3 racial/ethnic groups (Hispanic, non-Hispanic Black, and non-Hispanic White adolescents) who vary on underlying burden and amount of behavioral change. RESULTS: We estimated 1,118,483 cases of chlamydia and 214,762 cases of gonorrhea were averted (19.5% of burden across all ages). This yielded $474 million (2017 dollars) savings in medical costs over the decade. The largest number of averted cases (767,543) was among Black adolescents, but the largest proportion (28.7%) was among Hispanic adolescents. CONCLUSIONS: Whatever its origins, changing sexual behavior among adolescents results in large estimated reductions in STI burden and medical costs relative to previous cohorts. Although diagnoses among adolescents have not declined at this rate, multiple explanations could make these apparently divergent trends consistent. Efforts to continue supporting effective sex education in and out of school along with STI screening for adolescents should reinforce these gains.

Effects of Condom Use on Human Immunodeficiency Virus Transmission Among Adolescent Sexual Minority Males in the United States: A Mixed Epidemiology and Epidemic Modeling Study.

BACKGROUND: We examined condom use patterns and potential population-level effects of a hypothetical condom intervention on human immunodeficiency virus (HIV) transmission among adolescent sexual minority males (ASMM). METHODS: Using 3 data sets: national Youth Risk Behavior Survey 2015 to 2017 (YRBS-National), local YRBS data from 8 jurisdictions with sex of partner questions from 2011 to 2017 (YRBS-Trends), and American Men's Internet Survey (AMIS) 2014 to 2017, we assessed associations of condom use with year, age, and race/ethnicity among sexually active ASMM. Using a stochastic agent-based network epidemic model, structured and parameterized based on the above analyses, we calculated the percent of HIV infections averted over 10 years among ASMM ages 13 to 18 years by an intervention that increased condom use by 37% for 5 years and was delivered to 62% of ASMM at age 14 years. RESULTS: In YRBS, 51.8% (95% confidence interval [CI], 41.3-62.3%) and 37.9% (95% CI, 32.7-42.3%) reported condom use at last sexual intercourse in national and trend data sets, respectively. In AMIS, 47.3% (95% CI, 44.6-49.9%) reported condom use at last anal sex with a male partner. Temporal trends were not observed in any data set (P > 0.1). Condom use varied significantly by age in YRBS-National (P < 0.0001) and YRBS-Trends (P = 0.032) with 13- to 15-year-olds reporting the lowest use in both; age differences were not significant in AMIS (P = 0.919). Our hypothetical intervention averted a mean of 9.0% (95% simulation interval, -5.4% to 21.2%) of infections among ASMM. CONCLUSIONS: Condom use among ASMM is low and appears to have remained stable during 2011 to 2017. Modeling suggests that condom use increases, consistent with previous interventions, have potential to avert 1 in 11 new HIV infections among ASMM.

Potential Impact of HIV Preexposure Prophylaxis Among Black and White Adolescent Sexual Minority Males.

OBJECTIVES: To assess the potential impact of preexposure prophylaxis (PrEP) on the HIV epidemic among Black and White adolescent sexual minority males (ASMM). METHODS: We used a network model and race-specific data from recent trials to simulate HIV transmission among a population of Black and White 13- to 18-year-old ASMM over 20 years. We estimated the number of infections prevented (impact) and the number needed to treat to prevent an infection (efficiency) under multiple coverage and adherence scenarios. RESULTS: At modeled coverage and adherence, PrEP could avert 3% to 20% of infections among Black ASMM and 8% to 51% among White ASMM. A larger number, but smaller percentage, of infections were prevented in Black ASMM in all scenarios examined. PrEP was more efficient among Black ASMM (number needed to treat to avert an infection = 25-32) compared with White ASMM (146-237). CONCLUSIONS: PrEP can reduce HIV incidence among both Black and White ASMM but is far more efficient for Black ASMM because of higher incidence. Public Health Implications. Black ASMM communities suffer disproportionate HIV burden; despite imperfect adherence, PrEP programs could prevent HIV efficiently in these communities.

Modeling the Impact of PrEP Programs for Adolescent Sexual Minority Males Based on Empirical Estimates for the PrEP Continuum of Care.

PURPOSE: Pre-exposure prophylaxis (PrEP)-an effective and safe intervention to prevent HIV transmission-was recently approved by the Food and Drug Administration for use by adolescents. Informed by studies of sexual behavior and PrEP adherence, retention, and promotion, we model the potential impact of PrEP use among at-risk adolescent sexual minority males. METHODS: We simulate an HIV epidemic among men who have sex with men (MSM) aged 13-39. We assume adult MSM ages 19-39 have had PrEP available for 3 years with 20% coverage among eligible MSM based on the Centers for Disease Control and Prevention guidelines. PrEP interventions for ages 16-18 are then simulated using adherence and retention profiles drawn from the ATN113 and Enhancing Preexposure Prophylaxis in Community studies across a range of uptake parameters (10%-100%). Partnerships across age groups were modeled using parameterizations from the RADAR study. We compare the percent of incident infections averted (impact), person-years on PrEP per infection averted (efficiency), and changes in prevalence over 10 years. RESULTS: As compared to no PrEP use, baseline PrEP adherence and retention among adolescent sexual minority males drawn from the ATN113 and Enhancing Preexposure Prophylaxis in Community studies averted from 2.8% to 41.0% of HIV infections depending on the fraction of eligible adolescent sexual minority males that initiated PrEP at their annual health-care visit. Improved adherence and retention achieved with an array of focused interventions from real-world settings increased the percent of infections averted by as much as 26%-70%. CONCLUSIONS: Empirically demonstrated improvements in the PrEP continuum of care in response to existing interventions can substantially reduce incident HIV infections among adolescent sexual minority males.

Cost-Effectiveness of Pre-Exposure Prophylaxis Among Adolescent Sexual Minority Males.

PURPOSE: Pre-exposure prophylaxis (PrEP) has been proven safe and effective in preventing HIV among adolescent sexual minority males (ASMM), but the cost-effectiveness of PrEP in ASMM remains unknown. Building on a recent epidemiological network modeling study of PrEP among ASMM, we estimated the cost-effectiveness of PrEP use in a high prevalence U.S. setting with significant disparities in HIV between black and white ASMM. METHODS: Based on the estimated number of infections averted and the number of ASMM on PrEP from the previous model and published estimates of PrEP costs, HIV treatment costs, and quality-adjusted life years (QALYs) gained per infection prevented, we estimated the cost-effectiveness of PrEP use in black and white ASMM over 10 years using a societal perspective and lifetime horizon. Effectiveness was measured as lifetime QALYs gained. Cost estimates included 10-year PrEP costs and lifetime HIV treatment costs saved. Cost-effectiveness was measured as cost/QALY gained. Multiple sensitivity analyses were performed on key model input parameters and assumptions used. RESULTS: Under base-case assumptions, PrEP use yielded an incremental cost-effectiveness ratio of $33,064 per QALY in black ASMM and $427,788 per QALY in white ASMM. In all sensitivity analyses, the cost-effectiveness ratio of PrEP use remained <$100,000 per QALY in black ASMM and >$100,000 per QALY in white ASMM. CONCLUSIONS: We found favorable cost-effectiveness ratios for PrEP use among black ASMM or other ASMM in communities with high HIV burden at current PrEP costs. Clinicians providing services in high-prevalence communities, and particularly those serving high-prevalence communities of color, should consider including PrEP services.

Predicting the impact of sexual behavior change on adolescent STI in the US and New York State: a case study of the teen-SPARC tool.

PURPOSE: Adolescents aged 13-18 years bear a large burden of sexually transmitted infections (STIs) and changing adolescent sexual risk behavior is a key component of reducing this burden. We demonstrate a novel publicly available modeling tool (teen-SPARC) to help state and local health departments predict the impact of behavioral change on gonorrhea, chlamydia, and HIV burden among adolescents. METHODS: Teen-SPARC is built in Excel for familiarity and ease and parameterized using data from CDC's Youth Risk Behavior Surveillance System. We present teen-SPARC's methods, including derivation of national parameters and instructions to obtain local parameters. We model multiple scenarios of increasing condom use and estimate the impact on gonorrhea, chlamydia, and HIV incidence, comparing national and New York State (NYS) results. RESULTS: A 1% annual increase in condom use (consistent with Healthy People 2020 goals) could prevent nearly 10,000 cases of STIs nationwide. Increases in condom use of 17.1%, 2.2%, and 25.5% in NYS would be necessary to avert 1000 cases of gonorrhea, 1000 cases of chlamydia, and 10 cases of HIV infection, respectively. Additional results disaggregate outcomes by age, sex, partner sex, jurisdiction, and pathogen. CONCLUSION: Teen-SPARC may be able to assist health departments aiming to tailor behavioral interventions for STI prevention among adolescents.

Association between receipt of school-based HIV education and contraceptive use among sexually active high school students - United States, 2011-2013.

Sexual health education, including HIV prevention information, can help prevent unintended pregnancy and sexually transmitted infections. National Youth Risk Behavior Survey data from 2011 and 2013 were used to determine HIV education prevalence among 9,825 currently sexually active students in grades 9-12. Associations between HIV education and contraceptive methods used at last sexual intercourse were examined for: (1) condom use; (2) any contraceptive method; (3) dual use of a condom and either birth control pills; IUD or implant; or shot, patch, or birth control ring; and (4) primary contraceptive method. Primary contraceptive method options were (1) no method; (2) birth control pills; (3) condoms; (4) IUD or implant; (5) shot, patch, or birth control ring; (6) withdrawal or some other method; and (7) not sure. Logistic regression (prevalence ratios [PRs] and 95% confidence intervals [CIs]) and Chi-squares were used for testing. Students who received HIV education were more likely than students who did not to use a condom (PR:1.09;CI:1.01,1.18) and any contraceptive method (PR:1.08;CI:1.04,1.12); there was no significant association with dual use. Primary contraceptive method varied significantly by receipt of HIV education (p < .001). School-based HIV education may be important for promotion of adolescent condom and contraceptive use.

Modeling the joint effects of adolescent and adult PrEP for sexual minority males in the United States.

BACKGROUND: Pre-exposure prophylaxis (PrEP) is an effective and safe intervention approved for use to prevent HIV transmission. PrEP scale-up strategies and clinical practice are currently being informed by modeling studies, which have estimated the impact of PrEP in adult and adolescent MSM populations separately. This partitioning may miss important effects or yield biased estimates by excluding dependencies between populations. METHODS: We combined two published models of HIV transmission among adults and adolescent MSM. We simulated an HIV epidemic among MSM aged 13-39 without PrEP, with PrEP for adult MSM ages (19-39) and with the addition of PrEP for adolescents ages (16-18), comparing percent of incident infections averted (impact), the number of person-years on PrEP per infection averted (efficiency), and changes in prevalence. RESULTS: PrEP use among eligible 19-39 year old MSM averted 29.0% of infections and reduced HIV prevalence from 23.2% to 17.0% over ten years in the population as a whole. Despite being ineligible for PrEP in this scenario, prevalence among sexually active 18 year-olds declined from 6.0% to 4.3% due to reduced transmissions across age cohorts. The addition of PrEP for adolescents ages 16-18 had a small impact on the overall epidemic, further reducing overall prevalence from 17.0% to 16.8%; however prevalence among the sexually active 18 year-olds further declined from 4.3% to 3.8%. CONCLUSIONS: PrEP use among adults may significantly reduce HIV prevalence among MSM and may also have significant downstream effects on HIV incidence among adolescents; PrEP targeting adolescents remains an important intervention for HIV prevention.

Targeting Human Immunodeficiency Virus Pre-Exposure Prophylaxis to Adolescent Sexual Minority Males in Higher Prevalence Areas of the United States: A Modeling Study.

PURPOSE: Pre-exposure prophylaxis (PrEP) is an effective and safe intervention to prevent human immunodeficiency virus (HIV) transmission in men who have sex with men; current Centers for Disease Control and Prevention guidelines indicate its use among high-risk adults. Adolescent sexual minority males (ASMM) also have significant HIV risk, but implementation strategies are likely to differ for this population. We aimed to estimate impact and efficiency of PrEP for ASMM in higher prevalence US settings, using a variety of implementation strategies and assumptions about coverage, adherence, and background prevalence. METHODS: We develop a stochastic, dynamic, network-based model, parametrized using numerous ASMM behavioral and clinical data sources. We simulate 10 years with and without PrEP, comparing percent of incident infections averted (impact) and number of person-years on PrEP per infection averted (efficiency). RESULTS: Our main scenario (PrEP for 16- to 18-year-old ASMM, initiating PrEP 6 months after first anal intercourse, 40% coverage, adherence profiles from the ATN 113 trial; 2.9% background HIV prevalence among ASMM) prevents 27.8% of infections, with 38 person-years on PrEP per infection averted. Expanding implementation to cover younger ages or earlier initiation has small effects on impact and efficiency. Targeting highest risk ASMM increases efficiency, but requires querying sexual histories. Across levels examined, coverage and adherence do not have major impacts on efficiency, whereas background prevalence does. CONCLUSIONS: PrEP can have a large impact on HIV incidence among ASMM in the United States, especially in settings with high prevalence. However, willingness of, and support for, providers will be central to achieving the coverage needed to make this a success.

CDC's Early Response to a Novel Viral Disease, Middle East Respiratory Syndrome Coronavirus (MERS-CoV), September 2012-May 2014.

The first ever case of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) was reported in September 2012. This report describes the approaches taken by CDC, in collaboration with the World Health Organization (WHO) and other partners, to respond to this novel virus, and outlines the agency responses prior to the first case appearing in the United States in May 2014. During this time, CDC's response integrated multiple disciplines and was divided into three distinct phases: before, during, and after the initial activation of its Emergency Operations Center. CDC's response to MERS-CoV required a large effort, deploying at least 353 staff members who worked in the areas of surveillance, laboratory capacity, infection control guidance, and travelers' health. This response built on CDC's experience with previous outbreaks of other pathogens and provided useful lessons for future emerging threats.