Angela L. Hernandez

Estimated HIV Incidence in the United States, 2006–2009

Background The estimated number of new HIV infections in the United States reflects the leading edge of the epidemic. Previously, CDC estimated HIV incidence in the United States in 2006 as 56,300 (95% CI: 48,200–64,500). We updated the 2006 estimate and calculated incidence for 2007–2009 using improved methodology. Methodology We estimated incidence using incidence surveillance data from 16 states and 2 cities and a modification of our previously described stratified extrapolation method based on a sample survey approach with multiple imputation, stratification, and extrapolation to account for missing data and heterogeneity of HIV testing behavior among population groups. Principal Findings Estimated HIV incidence among persons aged 13 years and older was 48,600 (95% CI: 42,400–54,700) in 2006, 56,000 (95% CI: 49,100–62,900) in 2007, 47,800 (95% CI: 41,800–53,800) in 2008 and 48,100 (95% CI: 42,200–54,000) in 2009. From 2006 to 2009 incidence did not change significantly overall or among specific race/ethnicity or risk groups. However, there was a 21% (95% CI:1.9%–39.8%; p = 0.017) increase in incidence for people aged 13–29 years, driven by a 34% (95% CI: 8.4%–60.4%) increase in young men who have sex with men (MSM). There was a 48% increase among young black/African American MSM (12.3%–83.0%; p<0.001). Among people aged 13–29, only MSM experienced significant increases in incidence, and among 13–29 year-old MSM, incidence increased significantly among young, black/African American MSM. In 2009, MSM accounted for 61% of new infections, heterosexual contact 27%, injection drug use (IDU) 9%, and MSM/IDU 3%. Conclusions/Significance Overall, HIV incidence in the United States was relatively stable 2006–2009; however, among young MSM, particularly black/African American MSM, incidence increased. HIV continues to be a major public health burden, disproportionately affecting several populations in the United States, especially MSM and racial and ethnic minorities. Expanded, improved, and targeted prevention is necessary to reduce HIV incidence.

Using Molecular HIV Surveillance Data to Understand Transmission Between Subpopulations in the United States.

Background:Studying HIV transmission networks provides insight into the spread of HIV and opportunities for intervention. We identified transmission dynamics among risk groups and racial/ethnic groups in the United States. Methods:For HIV-1 pol sequences reported to the US National HIV Surveillance System during 2001–2012, we calculated pairwise genetic distance, identified linked pairs of sequences (those with distance ⩽1.5%), and examined transmission category and race/ethnicity of these potential transmission partners. Results:Of 40,950 sequences, 12,910 (32%) were linked to ≥1 other sequence. Of men who have sex with men (MSM) who were linked to ≥1 sequence, 88% were linked to other MSM and only 4% were linked to heterosexual women. Of heterosexual women for whom we identified potential transmission partners, 29% were linked to MSM, 21% to heterosexual men, and 12% to persons who inject drugs. Older and black MSM were more likely to be linked to heterosexual women. Assortative mixing was present for all racial/ethnic groups; 81% of blacks/African Americans linked to other blacks. Conclusions:This analysis is the first use of US surveillance data to infer an HIV transmission network. Our data suggest that HIV infections among heterosexual women predominantly originate from MSM, followed by heterosexual men. Although few MSM were linked to women, suggesting that a minority of MSM are involved in transmission with heterosexual women, these transmissions represent a substantial proportion of HIV acquisitions by heterosexual women. Interventions that reduce transmissions involving MSM are likely to also reduce HIV acquisition among other risk groups.

The Epidemiology of Human Immunodeficiency Virus Infection and Care among Adult and Adolescent Females in the United States, 2008-2012

OBJECTIVE We sought to determine epidemiological patterns in diagnoses of human immunodeficiency virus (HIV) infection and prevalence among females by age, race/ethnicity and transmission category, and essential steps in the continuum of HIV care. METHODS Using data from the National HIV Surveillance System, we estimated the number of females aged 13 years or older diagnosed with HIV infection in 2008 through 2012 and living with HIV at the end of 2011 in the United States. We determined percentages of females linked to care, retained in care, and virally suppressed in 18 jurisdictions with complete reporting of CD4 and viral load test results. RESULTS From 2008 to 2012, the estimated rate of HIV diagnoses among females decreased from 9.3 to 6.9 per 100,000 (-7.1% per year; 95% confidence interval [CI], -7.9, -6.3). In 2012, the diagnosis rate was highest among Blacks/African Americans (35.7), followed by Hispanics or Latinos (6.4), and Native Hawaiian Other Pacific Islander (5.1), and lowest among Whites (1.8). Most females diagnosed in 2012 were linked to care within 3 months of diagnosis (82.5%). About one-half (52.4%) of females living with HIV in 2011 received ongoing care in 2011 and 44.3% had a suppressed viral load. Viral suppression was lower among American Indian/Alaska Native (29.7%) and Black/African American (41.6%) compared with White females (46.5%). The percentage in care and with viral suppression was lower among younger compared with older females. CONCLUSION HIV diagnoses continue to decrease among females; however, disparities exist in HIV burden and viral suppression. Improvements in care and treatment outcomes are needed for all women with particular emphasis on younger women.

Mean Recency Period for Estimation of HIV-1 Incidence with the BED-Capture EIA and Bio-Rad Avidity in Persons Diagnosed in the United States with Subtype B

HIV incidence estimates are used to monitor HIV-1 infection in the United States. Use of laboratory biomarkers that distinguish recent from longstanding infection to quantify HIV incidence rely on having accurate knowledge of the average time that individuals spend in a transient state of recent infection between seroconversion and reaching a specified biomarker cutoff value. This paper describes five estimation procedures from two general statistical approaches, a survival time approach and an approach that fits binomial models of the probability of being classified as recently infected, as a function of time since seroconversion. We compare these procedures for estimating the mean duration of recent infection (MDRI) for two biomarkers used by the U.S. National HIV Surveillance System for determination of HIV incidence, the Aware BED EIA HIV-1 incidence test (BED) and the avidity-based, modified Bio-Rad HIV-1/HIV-2 plus O ELISA (BRAI) assay. Collectively, 953 specimens from 220 HIV-1 subtype B seroconverters, taken from 5 cohorts, were tested with a biomarker assay. Estimates of MDRI using the non-parametric survival approach were 198.4 days (SD 13.0) for BED and 239.6 days (SD 13.9) for BRAI using cutoff values of 0.8 normalized optical density and 30%, respectively. The probability of remaining in the recent state as a function of time since seroconversion, based upon this revised statistical approach, can be applied in the calculation of annual incidence in the United States.

Comparison of Rates of Death Having any Death-Certificate Mention of Heart, Kidney, or Liver Disease Among Persons Diagnosed with HIV Infection with those in the General US Population, 2009-2011

Objective : Compare age-adjusted rates of death due to liver, kidney, and heart diseases during 2009-2011 among US residents diagnosed with HIV infection with those in the general population. Methods : Numerators were numbers of records of multiple-cause mortality data from the national vital statistics system with an ICD-10 code for the disease of interest (any mention, not necessarily the underlying cause), divided into those 1) with and 2) without an additional code for HIV infection. Denominators were 1) estimates of persons living with diagnosed HIV infection from national HIV surveillance system data and 2) general population estimates from the US Census Bureau. We compared age-adjusted rates overall (unstratified by sex, race/ethnicity, or region of residence) and stratified by demographic group. Results : Overall, compared with the general population, persons diagnosed with HIV infection had higher age-adjusted rates of death reported with hepatitis B (rate ratio [RR]=42.6; 95% CI: 34.7-50.7), hepatitis C (RR=19.4; 95% CI: 18.1-20.8), liver disease excluding hepatitis B or C (RR=2.1; 95% CI: 1.8-2.3), kidney disease (RR=2.4; 95% CI: 2.2-2.6), and cardiomyopathy (RR=1.9; 95% CI: 1.6-2.3), but lower rates of death reported with ischemic heart disease (RR=0.6; 95% CI: 0.6-0.7) and heart failure (RR=0.8; 95% CI: 0.6-0.9). However, the differences in rates of death reported with the heart diseases were insignificant in some demographic groups. Conclusion : Persons with HIV infection have a higher risk of death with liver and kidney diseases reported as causes than the general population.

Transmission fitness of drug-resistant HIV revealed in a surveillance system transmission network

Test-and-treat programs are central to the global control of HIV, but transmitted drug resistance threatens the effectiveness of these programs. HIV mutations conferring resistance to antiretroviral drugs reduce replicative fitness in vitro, but their effect on propagation in vivo is less understood. Here, we estimate transmission fitness of these mutations in antiretroviral-naïve populations in the U.S. National HIV Surveillance System by comparing their frequency of clustering in a genetic transmission network relative with wild-type viruses. The large dataset (66,221 persons), comprising 30,196 antiretroviral-naïve persons, permitted the evaluation of sixty-nine resistance mutations. Decreased transmission fitness was demonstrated for twenty-three mutations, including M184V. In contrast, many high prevalence mutations (e.g. K103N, Y181C, and L90M) had transmission fitness that was indistinguishable from or exceeded wild-type fitness, permitting the establishment of large, self-sustaining drug resistance reservoirs. We highlight implications of these findings on strategies to preserve global treatment effectiveness.

HIV Testing Experience Before HIV Diagnosis Among Men Who Have Sex with Men — 21 Jurisdictions, United States, 2007–2013

Gay, bisexual, and other men who have sex with men (MSM) continue to be the population most affected by human immunodeficiency virus (HIV) in the United States. In 2014, 81% of diagnoses of HIV infection were among adult and adolescent males, and among these, 83% of infections were attributable to male-to-male sexual contact (1). Since 2006, CDC has recommended HIV testing at least annually for sexually active MSM to foster early detection of HIV infection and prevent HIV transmission (2,3). Several initiatives and strategies during the past decade have aimed to expand HIV testing among MSM to increase early diagnosis and treatment and reduce transmission. To better understand HIV testing patterns among MSM with diagnosed HIV infection, CDC analyzed data for 2007-2013 from jurisdictions conducting HIV incidence surveillance as part of CDCs National HIV Surveillance System (NHSS). Findings from this analysis suggest that increasing percentages of MSM have had a negative HIV test during the 12 months before diagnosis (48% in 2007, 56% in 2013, among those with a known date of previous negative HIV test), indicating a trend toward increased HIV testing and earlier HIV diagnosis among persons most at risk for HIV.

Vital Signs: Human Immunodeficiency Virus Testing and Diagnosis Delays — United States

Background Persons unaware of their human immunodeficiency virus (HIV) infection account for approximately 40% of ongoing transmissions in the United States. Persons are unaware of their infection because of delayed HIV diagnoses that represent substantial missed opportunities to improve health outcomes and prevent HIV transmission. Methods Data from CDC’s National HIV Surveillance System were used to estimate, among persons with HIV infection diagnosed in 2015, the median interval (and range) from infection to diagnosis (diagnosis delay), based on the first CD4 test after HIV diagnosis and a CD4 depletion model indicating disease progression and, among persons living with HIV in 2015, the percentage with undiagnosed infection. Data from CDC’s National HIV Behavioral Surveillance were analyzed to determine the percentage of persons at increased risk for HIV infection who had tested in the past 12 months and who had missed opportunities for testing. Results An estimated 15% of persons living with HIV in 2015 were unaware of their infection. Among the 39,720 persons with HIV infection diagnosed in 2015, the estimated median diagnosis delay was 3.0 years (interquartile range = 0.7–7.8 years); diagnosis delay varied by race/ethnicity (from 2.2 years among whites to 4.2 years among Asians) and transmission category (from 2.0 years among females who inject drugs to 4.9 years among heterosexual males). Among persons interviewed through National HIV Behavioral Surveillance, 71% of men who have sex with men, 58% of persons who inject drugs, and 41% of heterosexual persons at increased risk for HIV infection reported testing in the past 12 months. In each risk group, at least two thirds of persons who did not have an HIV test had seen a health care provider in the past year. Conclusions Delayed HIV diagnoses continue to be substantial for some population groups and prevent early entry to care to improve health outcomes and reduce HIV transmission to others. Implications for Public Health Practice Health care providers and others providing HIV testing can reduce HIV-related adverse health outcomes and risk for HIV transmission by implementing routine and targeted HIV testing to decrease diagnosis delays.

HIV Transmission Dynamics among Foreign-born Persons in the United States

Background: In the United States (US), foreign-born persons are disproportionately affected by HIV and differ epidemiologically from US-born persons with diagnosed HIV infection. Understanding HIV transmission dynamics among foreign-born persons is important to guide HIV prevention efforts for these populations. We conducted molecular transmission network analysis to describe HIV transmission dynamics among foreign-born persons with diagnosed HIV. Methods: Using HIV-1 polymerase nucleotide sequences reported to the US National HIV Surveillance System for persons with diagnosed HIV infection during 2001–2013, we constructed a genetic distance-based transmission network using HIV-TRACE and examined the birth region of potential transmission partners in this network. Results: Of 77,686 people, 12,064 (16%) were foreign born. Overall, 28% of foreign-born persons linked to at least one other person in the transmission network. Of potential transmission partners, 62% were born in the United States, 31% were born in the same region as the foreign-born person, and 7% were born in another region of the world. Most transmission partners of male foreign-born persons (63%) were born in the United States, whereas most transmission partners of female foreign-borns (57%) were born in their same world region. Discussion: These finding suggests that a majority of HIV infections among foreign-born persons in our network occurred after immigrating to the United States. Efforts to prevent HIV infection among foreign-born persons in the United States should include information of the transmission networks in which these individuals acquire or transmit HIV to develop more targeted HIV prevention interventions.

Receipt and timing of HIV drug resistance testing in six U.S. jurisdictions

ABSTRACT The Department of Health and Human Services recommends drug resistance testing at linkage to HIV care. Because receipt and timing of testing are not well characterized, we examined testing patterns among persons with diagnosed HIV who are linked to care. Using surveillance data in six jurisdictions for persons aged ≥13 years with HIV infection diagnosed in 2013, we assessed the proportion receiving testing, and among these, the proportion receiving testing at linkage. Multivariable log-binomial regression modeling estimated associations between selected characteristics and receipt of testing (1) overall, and (2) at linkage among those tested. Of 9,408 persons linked to care, 66% received resistance testing, among whom 68% received testing at linkage. Less testing was observed among male persons who inject drugs (PWID), compared with men who have sex with men (adjusted prevalence ratio [aPR]: 0.88; 95% confidence interval [CI]: 0.81–0.97) and persons living in areas with population <500,000 compared with those in areas with population ≥2,500,000 (aPR: 0.88; CI: 0.84–0.93). In certain jurisdictions, testing was lower for persons with initial CD4 counts ≥500 cells/mm3, compared with those with CD4 counts <200 cells/mm3 (aPR range: 0.80–0.85). Of those tested, testing at linkage was lower among male PWID (aPR: 0.85; CI: 0.75–0.95) and, in some jurisdictions, persons with CD4 counts ≥500 cells/mm3 (aPR range: 0.63–0.73). Two-thirds of persons with diagnosed HIV who were linked to care received resistance testing, and most received testing at linkage as recommended. Improving receipt and timing of testing among male PWID, persons in less populous settings, and in all jurisdictions, regardless of CD4 count, may improve care outcomes.