Conceived and designed the experiments: JP RS HIH. Analyzed the data: JP RS RZ. Contributed reagents/materials/analysis tools: JP RS AH RZ TG FW LSL QA HIH. Wrote the paper: JP RS. Interpretation of data: JP RS AH JM AL HIH.
¶ Membership of the HIV Incidence Surveillance Group is provided in the Acknowledgments.
Rebecca Ziebell is an employee of The Ginn Group, Peachtree City, Georgia, United States of America, a sub-contractor of the Northrop Grumman Corporation which provides scientific analysis services under contract to and as directed by the Centers for Disease Control and Prevention (CDC). This affiliation does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials.
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.
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.
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%.
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.
The Centers for Disease Control and Prevention (CDC) maintains an HIV surveillance system in which all states and U.S. territories submit data on reported diagnoses of HIV. The data are de-duplicated at CDC both within and across states, and the reported case counts are adjusted for reporting delay to estimate the number of new diagnoses of HIV infection and AIDS, annually
HIV surveillance is a dynamic system with additional data continually reported to state surveillance systems, and estimates of HIV diagnoses and incidence are updated to reflect these newly available data, science, and programmatic considerations. For example, the incidence estimation model is sensitive to sudden changes in HIV testing patterns which could influence estimates of HIV incidence
Since 1982, all 50 U.S. states and the District of Columbia have reported AIDS cases to CDC. In 1994, CDC began receiving reports of diagnosed HIV infection from the 25 states with confidential name-based HIV reporting. As of 2008, all 50 states, the District of Columbia and 5 territories submit de-identified data on reported diagnoses of HIV infection to CDC.
Since 2004, CDC has funded selected states and localities to conduct HIV incidence surveillance by (1) submitting remnant diagnostic HIV-positive blood specimens for testing using the serologic testing algorithm for recent HIV seroconversion (STARHS)
HIV incidence surveillance was designed to take advantage of national HIV surveillance by incorporating needed information on history of HIV testing and antiretroviral use and STARHS result data into routine case reporting in the states and cities that receive funding to conduct HIV incidence surveillance. From 2004 through 2007, 34 surveillance areas, including 27 state/territorial health departments and 7 city/county health departments, participated in HIV incidence surveillance. Since 2008, HIV incidence surveillance areas have included 25 health departments, including 18 state, and 7 city/county health departments. HIV incidence surveillance areas collect information on the self-reported date of first HIV antibody positive test, date of most recent HIV antibody negative test, number of negative HIV tests in the two years before testing positive, and antiretroviral usage (including beginning and ending dates, if applicable). In addition, HIV incidence surveillance coordinators in these areas collaborate with public and commercial laboratories to locate and ship remnant diagnostic blood specimens for testing using STARHS at a single national laboratory
Despite the relative advantage of using the existing HIV surveillance system and its resources to implement HIV incidence surveillance, health departments face logistical challenges in securing remnant HIV-positive blood specimens from multiple laboratories for use in STARHS. As a result of these challenges, remnant diagnostic blood specimens are frequently unavailable for STARHS. Although the percentage of cases reported to national HIV surveillance with a STARHS result has increased annually in all HIV incidence surveillance areas, in order to examine the temporal trend in incidence from 2006 through 2009, only those areas that met certain minimum criteria—15% completeness of STARHS results (as in previous analyses), confidential name-based reporting of HIV cases, and continuous implementation of HIV incidence surveillance throughout the entire analysis period—were included in this analysis. Those surveillance areas included 16 states (Alabama, Arizona, Colorado, Connecticut, Florida, Indiana, Louisiana, Michigan, Mississippi, New Jersey, New York, North Carolina, South Carolina, Texas, Virginia, and Washington) and 2 cities (Chicago and Philadelphia). While the minimum inclusion criterion was 15% completeness of STARHS results, the lowest level of completeness for any area was 17% in 2006, 20% in 2007, 27% in 2008 and 22% in 2009.
We included in the analysis new diagnoses of HIV infection (regardless of the stage of disease) among individuals aged 13 years and older at diagnosis in the years 2006 through 2009, with a residence at diagnosis in one of the aforementioned areas, and reported to CDC through June 2010. Data on STARHS results and history of HIV testing and antiretroviral use included data reported to CDC through January 2011 for these cases.
We estimated HIV incidence using the stratified extrapolation method described by Karon and colleagues
Previously, the probability of being detected in the STARHS recency period (
For new testers (i.e., those whose first HIV test was positive), the average group-level probability,
The other major improvement in the estimation procedure is the approach to handling missing transmission category. Previously, cases with missing transmission category were separated from those with known transmission category in the imputation and incidence estimation procedures. The estimated incidence in this group was then redistributed to other risk groups consistent with methods previously used to address missing risk factor information in national HIV surveillance data.
Following the previous model, incidence estimates were adjusted to account for those newly diagnosed but not yet reported HIV cases. Finally, the estimated incidence within the areas contributing data for estimation was extrapolated to the remaining U.S. areas to obtain a national estimate by applying the group-specific ratio of HIV incidence to diagnoses of AIDS within the areas contributing data to the number of new diagnoses of AIDS in the remaining U.S. areas. Population denominators for the calculation of rates were based on intercensal estimates for 2006—2009 obtained from the United States Census Bureau
The total number of persons aged 13 years and older diagnosed with HIV infection in the surveillance areas for the years 2006–2009 and reported through June 2010 was 29,279, 29,943, 28,831, and 27,040, respectively. Adjustment for reporting delay brought the totals to 30,702, 31,883, 31,357, and 31,162 respectively. Among individuals not diagnosed with AIDS within 6 months of HIV diagnosis, the number with BED results by year was 6,096 (31%) for 2006, 7,615 (37%) for 2007, 8,863 (44%) for 2008 and 9,615 (50%) for 2009. Among individuals who had a remnant diagnostic specimen tested with the BED in 2006, a higher percentage were black/African American, men who have sex with men (MSM) and in the youngest age group when compared to the distribution of new diagnoses. In 2007 a higher percentage were women, black/African American and in the youngest age group, and a lower percentage were injection drug users. In 2008 and 2009, a higher percentage were black/African American and in the youngest age group (
Based on the revised stratified extrapolation approach with a recalculated mean STARHS recency period using the BED of 162 days and using new diagnoses of HIV infection reported through June 2010, an estimated 48,600 individuals aged 13 years or older in the United States were infected with HIV in 2006 (95% CI: 42,400–54,700), with an additional 56,000 (95% CI: 49,100–62,900), 47,800 (95% CI: 41,800–53,800) and 48,100 (95% CI: 42,200–54,000) infected in 2007, 2008 and 2009, respectively. In each year, the most new infections occurred in males (accounting for 75%, 76%, 75%, and 77% of new infections respectively), MSM (56%, 58%, 56%, and 61%), and blacks/African Americans (44%, 42%, 46%, and 44%). The rate of new infections overall for 2006 through 2009 was estimated to be 19.8 (95% CI: 17.3–22.2), 22.5 (95% CI: 19.7–25.3), 19.0 (95% CI: 16.6–21.4), and 19.0 (95% CI: 16.6–21.3) per 100,000 individuals, respectively. Blacks/African Americans and Hispanics/Latinos experienced the heaviest impact of the epidemic with rates that were 7.4 and 2.8 times the rate in whites respectively in 2006, 7.1 and 3.0 times the rate in whites in 2007, 8.4 and 3.0 times the rate in whites in 2008, and 7.7 and 2.9 times the rate in whites in 2009 (
Each year, the highest rate of new infections was in black/African American males. Among females, blacks/African Americans also had the highest rates of new infections annually.
2006 | 2007 | ||||
|
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | |
Total |
48,600 [42,400–54,700] | 19.8 [17.3–22.2] | 56,000 [49,100–62,900] |
22.5 [19.7–25.3] | |
Sex | Male | 36,200 (75) [31,300–41,100] | 30.1 [26.0–34.2] | 42,400 (76) [36,900–47,900] |
34.9 [30.3–39.4] |
Female | 12,400 (25) [10,400–14,300] | 9.8 [8.3–11.4] | 13,600 (24) [11,500–15,800] | 10.7 [9.0–12.4] | |
Race/ethnicity | American Indian/Alaska Native | 150 (<1) [0–380] | 8.3 [0.0–20.9] | 210 (<1) [0–520] | 11.6 [0.0–28.2] |
Asian | 880 (2) [30–1,700] | 8.4 [0.3–16.4] | 1,200 (2) [330–2,200] | 11.5 [3.0–20.0] | |
Black/African American | 21,200 (44) [18,400–24,000] | 72.7 [63.0–82.4] | 23,400 (42) [20,400–26,500] | 79.2 [68.9–89.6] | |
Hispanic/Latino |
9,000 (18) [7,400–10,600] | 27.6 [22.6–32.5] | 11,200 (20) [9,300–13,100] |
33.4 [27.8–39.0] | |
Native Hawaiian/Other Pacific Islander | 130 (<1) [0–420] | 38.8 [0.0–124.5] | 190 (<1) [0–890] | 54.0 [0.0–258.4] | |
White | 16,600 (34) [13,800–19,400] | 9.8 [8.1–11.5] | 18,900 (34) [15,800–22,100] | 11.2 [9.3–13.0] | |
Multiple races | 680 (1) [330–1,000] | 25.4 [12.2–38.7] | 750 (1) [370–1,100] | 27.2 [13.3–41.0] | |
Age at infection (yr) | 13–29 | 15,600 (32) [13,100–18,000] | 21.8 [18.4–25.2] | 20,100 (36) [17,200–23,100] |
27.9 [23.8–32.0] |
30–39 | 14,900 (31) [12,500–17,400] | 37.0 [30.9–43.2] | 16,700 (30) [14,100–19,400] | 41.5 [35.0–48.0] | |
40–49 | 12,600 (26) [10,400–14,700] | 27.9 [23.1–32.7] | 13,100 (23) [11,000–15,200] | 29.3 [24.6–34.1] | |
50–99 | 5,500 (11) [4,300–6,700] | 6.2 [4.8–7.6] | 6,000 (11) [4,800–7,200] | 6.6 [5.2–7.9] | |
Transmission category | Male-to-male sexual contact | 27,000 (56) [23,000–31,000] | 32,300 (58) [27,800–36,800] |
||
Injection drug use | 5,300 (11) [4,000–6,600] | 5,900 (10) [4,500–7,200] | |||
Male-to-male sexual contact and Injection drug use | 1,900 (4) [1,200–2,700] | 1,900 (3) [1,300–2,600] | |||
Heterosexual contact |
14,300 (29) [11,900–16,600] | 15,700 (28) [13,400–18,100] | |||
Other |
80 (<1) [0–210] | 100 (<1) [0–270] |
2008 | 2009 | ||||
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | ||
Total |
47,800 [41,800–53,800] |
19.0 [16.6–21.4] | 48,100 [42,200–54,000] |
19.0 [16.6–21.3] | |
Sex | Male | 35,600 (75) [30,900–40,300] |
29.0 [25.2–32.9] | 36,900 (77) [32,200–41,600] |
29.8 [26.0–33.6] |
Female | 12,100 (25) [10,200–14,100] | 9.5 [7.9–11.0] | 11,200 (23) [9,200–13,100] |
8.6 [7.1–10.1] | |
Race/ethnicity | American Indian/Alaska Native | 220 (<1) [0–480] | 11.9 [0.0–26.0] | 260 (1) [0–640] | 14.0 [0.0–33.9] |
Asian | 1,100 (2) [350–1,800] | 9.7 [3.1–16.2] | 940 (2) [340–1,500] | 8.3 [3.0–13.6] | |
Black/African American | 21,900 (46) 18,900–25,000] | 73.2 [63.2–83.3] | 21,200 (44) [18,400–24,000] | 69.9 [60.6–79.1] | |
Hispanic/Latino |
9,000 (19) [7,500–10,600] |
26.1 [21.6–30.6] | 9,400 (20) [7,800–11,000] | 26.4 [22.0–30.9] | |
Native Hawaiian/Other Pacific Islander | 70 (<1) [0–790] | 20.0 [0.0–225.3] | 160 (<1) [0–980] | 43.7 [0.0–274.9] | |
White | 14,800 (31) [12,300–17,200] |
8.7 [7.2–10.1] | 15,600 (32) [13,000–18,200] |
9.1 [7.6–10.6] | |
Multiple races | 660 (1) [370–950] | 23.1 [12.9–33.4] | 520 (1) [250–800] | 17.9 [8.4–27.3] | |
Age at infection (yr) | 13–29 | 18,600 (39) [15,900–21,300] |
25.6 [21.8–29.4] | 18,800 (39) [16,100–21,600] |
25.8 [22.1–29.6] |
30–39 | 13,800 (29) [11,500–16,100] |
34.2 [28.6–39.8] | 13,000 (27) [10,900–15,100] |
32.2 [27.0–37.4] | |
40–49 | 10,400 (22) [8,600–12,300] |
23.6 [19.4–27.7] | 11,000 (23) [9,100–12,900] | 25.1 [20.8–29.4] | |
50–99 | 5,000 (10) [3,900–6,000] | 5.3 [4.2–6.4] | 5,200 (11) [4,100–6,400] | 5.5 [4.3–6.6] | |
Transmission category | Male-to-male sexual contact | 26,900 (56) [23,200–30,600] |
29,300 (61) [25,400–33,200] | ||
Injection drug use | 5,100 (11) [3,700–6,400] | 4,500 (9) [3,100–5,900] | |||
Male-to-male sexual contact and Injection drug use | 1,200 (3) [710–1,700] | 1,300 (3) [790–1,800] | |||
Heterosexual contact |
14,500 (30) [12,300–16,700] | 12,900 (27) [10,800–15,000] |
|||
Other |
120 (<1) [0–300] | 70 (<1) [0–210] |
CI, Confidence Interval. Confidence intervals reflect random variability affecting model uncertainty but may not reflect model-assumption uncertainty; thus, they should be interpreted with caution.
Because column totals for estimated numbers were calculated independently of the values for the subpopulations, the values in each column may not sum to the column total.
Hispanics/Latinos can be of any race.
Heterosexual contact with a person known to have, or to be at high risk for, HIV infection.
Includes hemophilia, blood transfusion, perinatal exposure, and risk factor not reported or not identified.
*Indicates significantly different (p<0.05) from the 2006 estimate for the same group.
**Indicates significantly different (p<0.05) from the 2007 estimate for the same group.
From 2006 to 2009 there was no significant change in HIV incidence overall and there was no significant change in incidence in any race/ethnicity group or risk group overall. There was an overall significant increase in HIV incidence from 2006 to 2007 (15%, 95% CI: 3.6%–26.8%; p = 0.006) with increases in men (17%, 95% CI: 3.0%–31.1%; p = 0.01), Hispanics/Latinos (24%, 95%CI: 0.2%–49.7%; p = 0.027), young people 13–29 years old (29%, 95% CI: 8.6%–49.7%; p = 0.002), and MSM (20%, 95% CI: 2.7%–36.8%; p = 0.013). In all of these groups, except young people, the estimated HIV incidence decreased significantly between 2007 and 2008, in each case falling below 2006 levels. In young people aged 13–29 years the estimated incidence of HIV infection decreased in 2008 as compared to 2007, but remained higher than in 2006, and this group was the only group to evidence a statistically significant increase in HIV incidence between 2006 and 2009 (
2006 | 2007 | ||||
|
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | |
|
|||||
|
13–29 | 5,300 (38) [4,200–6,400] | 103.2 [82.5–124.0] | 7,100 (46) [5,800–8,400] |
136.2 [110.8–161.5] |
30–39 | 3,700 (26) [2,800–4,600] | 154.3 [115.8–192.8] | 3,900 (25) [3,000–4,700] | 159.6 [122.8–196.4] | |
40–49 | 3,500 (25) [2,500–4,500] | 137.4 [97.0–177.8] | 2,900 (19) [2,200–3,700] | 116.7 [88.3–145.1] | |
50–99 | 1,600 (11) [1,000–2,200] | 44.4 [28.4–60.4] | 1,600 (10) [1,000–2,100] | 42.2 [28.0–56.4] | |
|
Male-to-male sexual contact | 9,000 (64) [7,400–10,700] | 10,400 (67) [8,600–12,200] | ||
Injection drug use | 1,600 (12) [970–2,300] | 1,500 (10) [980–2,100] | |||
Male-to-male sexual contact and Injection drug use | 700 (5) [340–1,100] | 540 (4) [240–850] | |||
Heterosexual contact |
2,700 (19) [1,900–3,500] | 3,000 (19) [2,300–3,700] | |||
|
14,100 [11,800–16,300] | 103.1 [86.7–119.4] | 15,500 [13,100–17,800] | 111.5 [94.8–128.1] | |
|
|||||
|
13–29 | 2,200 (30) [1,600–2,800] | 42.5 [30.5–54.4] | 3,000 (37) [2,300–3,700] |
57.8 [44.7–70.9] |
30–39 | 2,200 (31) [1,600–2,800] | 82.0 [61.0–103.0] | 2,300 (28) [1,600–2,900] | 84.2 [61.0–107.3] | |
40–49 | 1,900 (26) [1,300–2,400] | 63.9 [45.6–82.1] | 1,800 (23) [1,300–2,300] | 63.0 [44.8–81.1] | |
50–99 | 920 (13) [550–1,300] | 19.1 [11.4–26.8] | 940 (12) [570–1,300] | 18.8 [11.5–26.1] | |
|
Injection drug use | 1,100 (16) [700–1,500] | 1,400 (17) [830–1,900] | ||
Heterosexual contact |
6,000 (84) [4,900–7,100] | 6,600 (83) [5,400–7,900] | |||
|
7,100 [5,900–8,400] | 46.0 [38.0–54.0] | 8,000 [6,600–9,400] | 50.8 [42.0–59.6] | |
|
21,200 [18,400–24,000] | 72.7 [63.0–82.4] | 23,400 [20,400–26,500] | 79.2 [68.9–89.6] |
2008 | 2009 | ||||
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | ||
|
|||||
|
13–29 | 7,300 (50) [6,000–8,700] |
139.0 [113.3–164.7] | 7,600 (51) [6,300–8,900] |
143.2 [118.3–168.0] |
30–39 | 3,300 (23) [2,400–4,100] | 134.9 [100.7–169.2] | 3,400 (23) [2,600–4,300] | 139.9 [104.2–175.6] | |
40–49 | 2,700 (18) [2,000–3,400] | 106.5 [78.8–134.2] | 2,600 (18) [1,900–3,300] | 104.3 [76.1–132.5] | |
50–99 | 1,300 (9) [820–1,700] | 33.0 [21.3–44.7] | 1,200 (8) [770–1,600] | 29.3 [19.2–39.4] | |
|
Male-to-male sexual contact | 9,800 (68) [8,200–11,500] | 10,800 (73) [9,100–12,500] | ||
Injection drug use | 1,500 (11) [910–2,200] | 1,200 (8) [610–1,700] | |||
Male-to-male sexual contact and Injection drug use | 350 (2) [160–540] | 360 (2) [140–570] | |||
Heterosexual contact |
2,800 (19) [2,100–3,500] | 2,400 (17) [1,800–3,100] | |||
|
14,500 [12,400–16,700] | 103.4 [87.9–119.0] | 14,800 [12,600–16,900] | 103.9 [88.8–119.0] | |
|
|||||
|
13–29 | 2,500 (33) [1,900–3,000] | 47.6 [36.8–58.4] | 2,300 (36) [1,700–2,800] | 43.8 [33.4–54.2] |
30–39 | 2,300 (32) [1,700–2,900] | 87.2 [64.5–109.9] | 1,700 (27) [1,200–2,200] | 63.5 [46.0–81.0] | |
40–49 | 1,600 (22) [1,200–2,100] | 57.3 [40.5–74.2] | 1,400 (22) [990–1,900] | 50.5 [34.8–66.2] | |
50–99 | 950 (13) [570–1,300] | 18.5 [11.0–25.9] | 960 (15) [570–1,300] | 18.0 [10.6–25.3] | |
|
Injection drug use | 1,100 (15) [610–1600] | 940 (15) [450–1,400] | ||
Heterosexual contact |
6,300 (85) [5,200–7,400] | 5,400 (85) [4,500–6,400] | |||
|
7,400 [6,100–8,700] | 46.6 [38.3–54.8] | 6,400 [5,300–7,500] |
39.7 [32.7–46.8] | |
|
21,900 [18,900–25,000] | 73.2 [63.2–83.3] | 21,200 [18,400–24,000] | 69.9 [60.6–79.1] |
CI, Confidence Interval. Confidence intervals reflect random variability affecting model uncertainty but may not reflect model-assumption uncertainty; thus, they should be interpreted with caution.
Heterosexual contact with a person known to have, or to be at high risk for, HIV infection.
Because column subtotals and totals for estimated numbers were calculated independently of the values for the subpopulations, the values in each column may not sum to the column subtotal or total.
*Indicates significantly different (p<0.05) from the 2006 estimate for the same group.
**Indicates significantly different (p<0.05) from the 2007 estimate for the same group.
2006 | 2007 | ||||
|
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | |
|
|||||
|
13–29 | 2,600 (37) [1,800–3,400] | 37.6 [26.3–49.0] | 3,500 (38) [2,600–4,400] | 49.6 [36.5–62.7] |
30–39 | 2,400 (34) [1,600–3,100] | 61.6 [42.4–80.8] | 3,100 (34) [2,200–4,000] | 77.4 [55.2–99.6] | |
40–49 | 1,500 (21) [890–2,100] | 51.6 [30.8–72.4] | 1,900 (21) [1,300–2,600] | 63.8 [41.7–85.9] | |
50–99 | 460 (7) [160–770] | 14.6 [4.9–24.3] | 630 (7) [330–940] | 18.8 [9.7–27.8] | |
|
Male-to-male sexual contact | 5,200 (75) [4,100–6,400] | 6,800 (75) [5,400–8,200] |
||
Injection drug use | 600 (9) [270–920] | 940 (10) [500–1,400] | |||
Male-to-male sexual contact and Injection drug use | 280 (4) [80–480] | 370 (4) [110–630] | |||
Heterosexual contact |
830 (12) [370–1,300] | 1,000 (11) [550–1,400] | |||
|
7,000 [5,600–8,400] | 41.2 [32.9–49.5] | 9,200 [7,500–10,800] |
52.5 [42.8–62.2] | |
|
|||||
|
13–29 | 750 (37) [430–1,100] | 12.5 [7.1–17.8] | 780 (38) [390–1,200] | 12.7 [6.3–19.2] |
30–39 | 580 (29) [280–890] | 17.6 [8.5–26.7] | 580 (28) [310–850] | 17.0 [9.1–24.9] | |
40–49 | 410 (20) [200–630] | 15.4 [7.4–23.4] | 440 (21) [170–710] | 15.9 [6.2–25.5] | |
50–99 | 270 (13) [20–520] | 7.4 [0.4–14.3] | 260 (12) [50–470] | 6.7 [1.2–12.1] | |
|
Injection drug use | 310 (15) [70–550] | 330 (16) [80–570] | ||
Heterosexual contact |
1,700 (85) [1,100–2,300] | 1,700 (84) [1,100–2,300] | |||
|
2,000 [1,400–2,600] | 12.9 [9.0–16.7] | 2,100 [1,400–2,700] | 12.7 [8.7–16.8] | |
|
9,000 [7,400–10,600] | 27.6 [22.6–32.5] | 11,200 [9,300–13,100] |
33.4 [27.8–39.0] |
2008 | 2009 | ||||
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | ||
|
|||||
|
13–29 | 3,100 (43) [2,300–3,900] | 43.0 [32.1–53.8] | 3,000 (41) [2,300–3,800] | 41.9 [31.5–52.3] |
30–39 | 2,500 (34) [1,800–3,200] | 59.9 [42.5–77.3] | 2,600 (35) [1,800–3,300] | 60.6 [43.0–78.2] | |
40–49 | 1,200 (16) [750–1,600] |
37.1 [24.0–50.3] | 1,300 (18) [840–1,800] | 40.8 [25.6–55.9] | |
50–99 | 480 (7) [200–750] | 13.3 [5.6–21.0] | 460 (6) [200–730] | 12.3 [5.2–19.2] | |
|
Male-to-male sexual contact | 5,500 (76) [4,400–6,600] | 6,000 (81) [4,800–7,100] | ||
Injection drug use | 680 (10) [300–1,100] | 560 (8) [180–950] | |||
Male-to-male sexual contact and Injection drug use | 240 (3) [40–430] | 230 (3) [40–410] | |||
Heterosexual contact |
790 (11) [430–1,100] | 640 (9) [350–930] | |||
|
7,200 [5,900–8,500] |
40.0 [32.7–47.3] | 7,400 [6,000–8,800] | 39.9 [32.6–47.3] | |
|
|||||
|
13–29 | 730 (39) [380–1,100] | 11.6 [6.0–17.1] | 750 (37) [280–1,200] | 11.6 [4.3–19.0] |
30–39 | 530 (29) [240–820] | 15.3 [7.0–23.6] | 560 (27) [240–870] | 15.7 [6.9–24.6] | |
40–49 | 440 (23) [200–670] | 15.2 [7.0–23.5] | 480 (24) [210–760] | 16.4 [7.1–25.7] | |
50–99 | 160 (9) [30–290] | 4.0 [0.8–7.2] | 240 (12) [20–450] | 5.6 [0.6–10.7] | |
|
Injection drug use | 280 (15) [80–480] | 370 (18) [0–740] | ||
Heterosexual contact |
1,600 (85) [1,000–2,100] | 1,700 (82) [1,100–2,200] | |||
|
1,900 [1,300–2,400] | 11.1 [7.6–14.7] | 2,000 [1,300–2,700] | 11.8 [7.7–15.9] | |
|
9,000 [7,500–10,600] |
26.1 [21.6–30.6] | 9,400 [7,800–11,000] | 26.4 [22.0–30.9] |
Hispanics/Latinos can be of any race.
CI, Confidence Interval. Confidence intervals reflect random variability affecting model uncertainty but may not reflect model-assumption uncertainty; thus, they should be interpreted with caution.
Heterosexual contact with a person known to have, or to be at high risk for, HIV infection.
Because column subtotals and totals for estimated numbers were calculated independently of the values for the subpopulations, the values in each column may not sum to the column subtotal or total.
*Indicates significantly different (p<0.05) from the 2006 estimate for the same group.
**Indicates significantly different (p<0.05) from the 2007 estimate for the same group.
2006 | 2007 | ||||
|
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | |
|
|||||
|
13–29 | 3,200 (23) [2,100–4,200] | 14.4 [9.7–19.1] | 3,900 (24) [2,600–5,200] | 17.6 [11.8–23.3] |
30–39 | 4,700 (34) [3,400–6,000] | 37.4 [26.7–48.0] | 5,400 (34) [3,900–6,900] | 43.5 [31.6–55.3] | |
40–49 | 4,200 (31) [3,100–5,400] | 27.0 [19.6–34.4] | 4,600 (29) [3,400–5,900] | 30.3 [22.2–38.3] | |
50–99 | 1,700 (12) [1,100–2,400] | 5.4 [3.4–7.3] | 2,000 (13) [1,300–2,800] | 6.2 [4.1–8.4] | |
|
Male-to-male sexual contact | 11,700 (85) [9,500–13,900] | 13,700 (86) [11,200–16,300] | ||
Injection drug use | 590 (4) [210–970] | 650 (4) [210–1,100] | |||
Male-to-male sexual contact and Injection drug use | 880 (6) [380–1,400] | 950 (6) [450–1,500] | |||
Heterosexual contact |
600 (4) [180–1,000] | 580 (4) [200–950] | |||
|
13,800 [11,300–16,300] | 16.8 [13.7–19.8] | 16,000 [13,200–18,700] | 19.3 [15.9–22.7] | |
|
|||||
|
13–29 | 970 (35) [380–1,600] | 4.6 [1.8–7.4] | 970 (32) [350–1,600] | 4.6 [1.7–7.5] |
30–39 | 810 (29) [400–1,200] | 6.6 [3.2–9.9] | 880 (29) [450–1,300] | 7.2 [3.7–10.7] | |
40–49 | 660 (24) [320–1,000] | 4.2 [2.1–6.3] | 820 (27) [370–1,300) | 5.3 [2.4–8.3] | |
50–99 | 330 (12) [80–580] | 0.9 [0.2–1.5] | 320 (11) [100–530] | 0.8 [0.3–1.4] | |
|
Injection drug use | 860 (31) [310–1,400] | 830 (28) [430–1,200] | ||
Heterosexual contact |
1,900 (69) [1,200–2,600] | 2,100 (72) [1,300–3,000] | |||
|
2,800 [1,900–3,700] | 3.2 [2.2–4.2] | 3,000 [2,000–4,000] | 3.4 [2.3–4.6] | |
|
16,600 [13,800–19,400] | 9.8 [8.1–11.5] | 18,900 [15,800–22,100] | 11.2 [9.3–13.0] |
2008 | 2009 | ||||
Incidence, No. (%) [95% CI] |
Rate [95% CI] | Incidence, No. (%) [95% CI] |
Rate [95% CI] | ||
|
|||||
|
13–29 | 3,400 (27) [2,300–4,500] | 15.2 [10.3–20.1] | 3,700 (28) [2,500–4,800] | 16.5 [11.3–21.6] |
30–39 | 3,900 (31) [2,800–4,900] | 31.4 [22.6–40.3] | 3,700 (28) [2,600–4,700] |
30.2 [21.4–39.0] | |
40–49 | 3,600 (29) [2,600–4,600] | 23.9 [17.4–30.5] | 4,000 (30) [2,900–5,200] | 27.5 [19.6–35.3] | |
50–99 | 1,600 (13) [1,000–2,200] | 4.8 [3.1–6.4] | 1,900 (14) [1,200–2,600] | 5.6 [3.6–7.6] | |
|
Male-to-male sexual contact | 10,500 (85) [8,600–12,400] |
11,400 (86) [9,300–13,500] | ||
Injection drug use | 660 (5) [150–1,200] | 640 (5) [110–1,200] | |||
Male-to-male sexual contact and Injection drug use | 550 (4) [210–880] | 670 (5) [280–1,100] | |||
Heterosexual contact |
670 (5) [220–1,100] | 550 (4) [100–1,000] | |||
|
12,400 [10,200–14,600] |
14.9 [12.3–17.6] | 13,300 [11,000–15,600] | 15.9 [13.2–18.7] | |
|
|||||
|
13–29 | 810 (34) [260–1,400] | 3.8 [1.2–6.4] | 740 (32) [280–1,200] | 3.5 [1.3–5.7] |
30–39 | 740 (32) [350–1,100] | 6.1 [2.9–9.3] | 560 (24) [190–920] | 4.6 [1.6–7.7] | |
40–49 | 500 (21) [210–790] | 3.3 [1.4–5.2] | 710 (31) [220–1,200] | 4.8 [1.5–8.2] | |
50–99 | 300 (13) [100–510] | 0.8 [0.2–1.3] | 310 (13) [60–560] | 0.8 [0.1–1.4] | |
|
Injection drug use | 610 (26) [210–1,000] | 650 (28) [180–1,100] | ||
Heterosexual contact |
1,700 (74) [1,100–2,400] | 1,700 (72) [920–2,400] | |||
|
2,300 [1,600–3,100] | 2.7 [1.8–3.6] | 2,300 [1,500–3,200] | 2.6 [1.7–3.6] | |
|
14,800 [12,300–17,200] |
8.7 [7.2–10.1] | 15,600 [13,000–18,200] |
9.1 [7.6–10.6] |
CI, Confidence Interval. Confidence intervals reflect random variability affecting model uncertainty but may not reflect model-assumption uncertainty; thus, they should be interpreted with caution.
Heterosexual contact with a person known to have, or to be at high risk for, HIV infection.
Because column subtotals and totals for estimated numbers were calculated independently of the values for the subpopulations, the values in each column may not sum to the column subtotal or total.
Indicates significantly different (p<0.05) from the 2007 estimate for the same group.
Among the 13–29 year age group, by year, MSM made up 62%, 64%, 65%, and 69% of new infections, including 59%, 58%, 62%, and 66% of new infections among blacks/African Americans, 63%, 68% 65%, and 72% of new infections among Hispanics/Latinos, and 65%, 70%, 71%, and 72% of new infections among whites. Within MSM there were racial/ethnic differences in the age distribution of new infections. Among black/African American and Hispanic/Latino MSM, most new infections occurred in the youngest MSM, with MSM 13–29 accounting for 49%, 57%, 62%, and 60% of new infections by year among blacks/African Americans and 40%, 43%, 46%, and 45% of new infections by year among Hispanics/Latinos, compared with 23%, 25%, 28%, and 28% among whites (
HIV incidence in all MSM 13–29 demonstrated a statistically significant estimated annual percentage change (EAPC) of 8.1% (95% CI: 1.9%–14.9%; p = 0.01). The EAPC for young black/African American MSM was 12.2% (95% CI: 4.2%–20.9%; p = 0.002) but was not significant for other young MSM.
2006 | 2007 | 2008 | 2009 | ||
|
Incidence, No. (%) [95% CI] |
Incidence, No. (%) [95% CI] |
Incidence, No. (%) [95% CI] |
Incidence, No. (%) [95% CI] |
|
|
9,000 [7,400–10,700] | 10,400 [8,600–12,200] | 9,800 [8,200–11,500] | 10,800 [9,100–12,500] | |
|
13–29 | 4,400 (49) [3,500–5,400] | 5,900 (57) [4,700–7,100] |
6,100 (62) [4,900–7,300] |
6,500 (60) [5,300–7,700] |
30–39 | 2,300 (26) [1,600–3,000] | 2,500 (24) [1,800–3,200] | 2,000 (21) [1,400–2,600] | 2,500 (23) [1,800–3,200] | |
40–49 | 1,700 (19) [1,100–2,300] | 1,400 (14) [960–1,900] | 1,300 (13) [840–1,700] | 1,400 (13) [870–1,800] | |
50–99 | 560 (6) [230–880] | 560 (5) [240–880] | 430 (4) [190–670] | 450 (4) [210–700] | |
|
5,200 [4,100–6,400] | 6,800 [5,400–8,200] |
5,500 [4,400–6,600] | 6,000 [4,800–7,100] | |
|
13–29 | 2,100 (40) [1,400–2,800] | 2,900 (43) [2,100–3,700] | 2,500 (46) [1,800–3,200] | 2,700 (45) [2,000–3,400] |
30–39 | 1,900 (36) [1,200–2,600] | 2,300 (33) [1,600–3,000] | 1,900 (35) [1,300–2,500] | 2,000 (34) [1,300–2,700] | |
40–49 | 1,000 (19) [530–1,500] | 1,300 (19) [720–1,800] | 790 (14) [450–1,100] | 1,000 (17) [590–1,400] | |
50–99 | 230 (4) [0–460] | 360 (5) [140–590] | 240 (4) [60–410] | 300 (5) [90–500] | |
|
11,700 [9,500–13,900] | 13,700 [11,200–16,300] | 10,500 [8,600–12,400] |
11,400 [9,300–13,500] | |
|
13–29 | 2,700 (23) [1,800–3,600] | 3,400 (25) [2,300–4,600] | 3,000 (28) [2,000–3,900] | 3,200 (28) [2,200–4,200] |
30–39 | 4,100 (35) [2,900–5,300] | 4,700 (34) [3,300–6,000] | 3,300 (31) [2,300–4,200] | 3,200 (28) [2,300–4,200] | |
40–49 | 3,500 (30) [2,500–4,500] | 3,900 (29) [2,800–5,000] | 3,000 (28) [2,200–3,800] | 3,400 (30) [2,500–4,400] | |
50–99 | 1,400 (12) [850–1,900] | 1,700 (13) [1,100–2,400] | 1,300 (12) [810–1,700] | 1,600 (14) [970–2,200] | |
|
27,000 [23,000–31,000] | 32,300 [27,800–36,800] |
26,900 [23,200–30,600] |
29,300 [25,400–33,200] | |
|
13–29 | 9,600 (36) [7,900–11,300] | 12,800 (39) [10,600–14,900] |
12,100 (45) [10,100–14,100] |
12,900 (44) [10,800–14,900] |
30–39 | 8,600 (32) [6,800–10,500] | 9,900 (30) [7,900–11,800] | 7,500 (28) [6,100–9,000] | 8,000 (27) [6,400–9,500] | |
40–49 | 6,500 (24) [5,100–7,900] | 6,900 (21) [5,500–8,400] | 5,300 (20) [4,100–6,500] | 6,000 (21) [4,700–7,300] | |
50–99 | 2,300 (8) [1,600–3,000] | 2,800 (9) [1,900–3,600] | 2,000 (8) [1,400–2,600] | 2,400 (8) [1,700–3,100] |
Hispanics/Latinos can be of any race.
CI, Confidence Interval. Confidence intervals reflect random variability affecting model uncertainty but may not reflect model-assumption uncertainty; thus, they should be interpreted with caution.
Because column totals for estimated numbers were calculated independently of the values for the subpopulations, the values in each column may not sum to the column total.
*Indicates significantly different (p<0.05) from the 2006 estimate for the same group.
**Indicates significantly different (p<0.05) from the 2007 estimate for the same group.
Rather than expand the analysis to include in each year's analysis all areas that met the inclusion criteria for that year, we chose to limit the surveillance areas contributing data for analysis to those that met the inclusion criteria for
Based on the revised stratified extrapolation approach for estimating HIV incidence, the number of new infections in the United States remained relatively stable between 2006 and 2009. Our analysis examines HIV incidence over a four-year period to provide the clearest picture of the current status of trends in incidence. The only population with a change in HIV incidence over the entire four-year period was 13–29 year olds, and within that age group, the only risk group experiencing increases was MSM. Among young MSM the estimated number of new infections increased significantly from 2006–2009; the increase in incidence in this group was largely driven by a statistically significant increase in new HIV infections of 48% (12.2% annually) in young, black/African American MSM.
The point estimate of the number of new HIV infections in 2006 presented here is somewhat lower than the previous estimate but within the confidence interval of that estimate
Consistent with the higher rates of HIV diagnoses among MSM in general
These estimates are subject to several limitations. First, in order to maintain consistency across the analysis years, we limited our analysis to only those states that consistently met the inclusion criteria for all analysis years. Therefore, the estimates are based on data from 16 states and 2 cities. The included areas represented 61% of reported cases of AIDS in the United States for the years 2006 and 2009, 62% for the years 2007 and 2008.
Because data were only available for a limited number of surveillance areas, we extrapolated our HIV incidence estimates from the included areas to the rest of the United States by applying the ratio of HIV incidence to AIDS incidence in the included areas to the AIDS incidence in the rest of the United States. To evaluate the validity of this extrapolation we compared the ratio of HIV diagnoses (as a proxy for incidence) to AIDS diagnoses in the included areas to that ratio in the areas to which we extrapolated. By extrapolating from the same surveillance areas each year, we may have underestimated HIV incidence overall by approximately 4%; using different areas each year, we may have underestimated HIV incidence by about 3%. Additionally, while the represented areas included several jurisdictions with very high morbidity, others—including the District of Columbia and the state of California—were not included in the estimate. Because HIV incidence in an area is driven by both risk behavior and HIV prevalence, the HIV incidence estimate may have been higher if these areas had been included. However, our method of extrapolating to the United States as a whole using the same 68 strata used for estimation likely compensates for the lack of inclusion of some cities with high HIV morbidity. It also limits overestimation of HIV incidence due to the differing ratio of HIV diagnoses to AIDS diagnoses in the incidence versus non-incidence areas.
Next, an assumption of the model is that HIV testing behavior has not changed over several years
Additionally, concerns about using the BED assay within STARHS for cross-sectional estimation of HIV incidence have been raised for some HIV subtypes due to the misclassification of long-standing infections as recent
In our previous work we noted that the HIV incidence estimate for 2006 could have been an overestimate if we had underestimated the likelihood of testing for HIV within one year of infection. The revised model for incidence estimation presented here addresses this concern by using the entire distribution of the STARHS recency period which limits the impact on the weights assigned to repeat testers who test more frequently than once per year, thus limiting the amount of overestimation bias inherent in the previous model. It is still possible, however that we could have overestimated incidence if a significant number of individuals were motivated to be tested for HIV by a real or perceived recent exposure, as this motivation was not addressed in the estimation model. We previously estimated that we may have overestimated HIV incidence by as much as 7% as a result of excluding motivation from the model to calculate incidence
Finally, a number of additional assumptions of the model have been previously described
The estimates for 2006–2009 continue to underscore the disproportionate toll that the HIV epidemic has taken on several populations in the United States including racial/ethnic and sexual minorities and injection drug users with 95% of new infections 2006–2009 estimated to have occurred in individuals in one or more of these groups. Though transmission rates have decreased substantially since the beginning of the epidemic
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HIV Incidence Surveillance Group: Catina L. James, M.P.H.,
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.