CDC Estimates 3-Year Average Gap Between HIV Transmission and Diagnosis in U.S.

A new analysis by the Centers for Disease Control and Prevention (CDC) estimates that in 2015 the median time between HIV acquisition and diagnosis was approximately three years, with approximately 15% of people living with HIV being unaware that they carried the virus.

The CDC has previously reported that HIV-positive people unaware of their status account for 40% of HIV transmissions in the United States. The CDC revised its recommendations for routinized HIV testing in 2006. Increased HIV testing boosted the percentage of U.S. residents aware that they acquired HIV to about 85% in 2014, close to the national (and international) goal of 90% by 2020. This new study sought to estimate the period of delay between HIV transmission and diagnosis.

The CDC team used data from the National HIV Surveillance System through June 2017 to estimate the total number of people living with HIV at the end of 2015 and the median number of years between infection and diagnosis among people diagnosed in 2015. The researchers calculated the number of undiagnosed HIV infections by subtracting reported cumulative diagnoses from estimated cumulative infections. They used data from the National HIV Behavioral Surveillance (NHBS) to figure percentages of people at increased risk for HIV who were tested in the past 12 months and percentages with a health care visit in that period who missed opportunities for testing.

Among 1,122,900 people living with HIV in the United States in 2015, an estimated 162,500 (14.5%) did not know they had the virus. The South accounted for half of undiagnosed HIV infections (50.5%). Among 39,720 people diagnosed with HIV in 2015, more than one in five (21.6%) had AIDS.

Related: This Week in HIV Research: Average Time Between Diagnosis and Linkage to Care

Median delay between HIV acquisition and diagnosis across the U.S. stood at three years. Overall, one-quarter of people diagnosed in 2015 had been HIV positive for seven or more years without knowing it. The delay between transmission and diagnosis was longer among males than females (3.1 versus 2.4 years), longer among people 55 or older than 13- to 24-year-olds (4.5 versus 2.4 years), and longer among Asians (4.2 years) than blacks or Hispanics (3.3 years) or whites (2.2 years) (P < .01 for all). Among HIV transmission groups, men who acquired HIV heterosexually had the longest median delay between transmission and diagnosis: 4.9 years.

Among survey respondents, the proportion reporting an HIV test in the past 12 months rose among three transmission risk groups: from 63% in 2008 to 71% in 2014 among men who have sex with men (MSM), from 50% in 2009 to 58% in 2015 among people who inject drugs, and from 34% in 2010 to 41% in 2016 among heterosexuals at high risk. In all three risk groups, two-thirds or more without an HIV test had seen a health care provider in the past year (67.2% of MSM, 71.5% of drug injectors, and 74.8% of heterosexuals). Among people who had a health care visit and did not get tested, about three-quarters said they were not offered an HIV test.

The CDC recommends HIV testing at least once for everyone in the U.S. between 13 and 64 years old and yearly HIV testing for people considered high risk. CDC researchers who conducted this study note that testing in the past 12 months rose through recent years for all three risk groups, but high proportions of people at risk remain untested (29% of MSM, 42% of drug injectors, and 59% of heterosexuals at high risk). "For care and treatment to reduce HIV incidence effectively," they stress, "a high proportion of cases need to be diagnosed and treated soon after infection occurs."