NYC Health Department Estimates Yearly HIV Infections

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New York City Health Department released the most precise estimate yet of annual citywide HIV infections. The findings, derived from a new formula developed by the federal Centers for Disease Control and Prevention, indicate that nearly 4,800 New Yorkers contracted HIV in 2006. The Health Department has long tracked the number of people newly diagnosed each year but, in most cases, hasn’t been able to distinguish recent infections from those that occurred years earlier. Because this is the first attempt to estimate HIV incidence (or new infections) by this technique, the number cannot be characterized as an increase or a decline. But the finding suggests that New Yorkers are contracting HIV at three times the national rate.

New York City, with more than 100,000 people living with HIV, has long been considered the epicenter of the U.S. epidemic. The new incidence estimate supports that impression, showing that 72 of every 100,000 of New Yorkers were newly infected in 2006, compared to 23 per 100,000 nationally. The reasons for that disparity are partly demographic. The populations that bear the greatest burden nationally – blacks, for example, and men who have sex with men – are highly represented in New York City. Because HIV is more prevalent within those groups, the risk of HIV infection per sexual contact is higher.

To estimate the city’s incidence rate, Health Department researchers started with the total number of new HIV diagnoses made during 2006 (3,863 in New York City) and used a laboratory test to distinguish recent from long-standing infections. They then used the CDC’s new statistical technique to estimate the total number of recent infections, both among people who were tested and among people who weren’t. By combining the two calculations, they were able to estimate incidence for the city as a whole and for many subgroups.

The analytic technique is new, and the estimates may be imprecise, but even a rough gauge of HIV incidence is a valuable tool for understanding – and combating – the spread of HIV. The Health Department’s new estimate includes 2006 incidence figures for different age groups, racial groups and both genders. By repeating the exercise for subsequent years, researchers may be able to discern increases and decreases over time, and target their prevention efforts accordingly.

“HIV incidence is the leading edge of the epidemic,” said Dr. Monica Sweeney, the Health Department’s Assistant Commissioner for HIV Prevention and Control. “It shows who is getting infected now and where we need to direct resources for prevention, testing, linkage to care, and partner notification.”

Most at risk

The new estimates suggest that black New Yorkers and men, especially those who have sex with other men, were the groups at greatest risk in 2006. Men made up more than three quarters of new infections in New York City (as they did nationally), meaning their incidence rate was more than three times higher than women’s (see tables below). The incidence rate among NYC men was 117 per 100,000. The rate in women was 33 per 100,000. Nationally, the incidence rates were lower than NYC’s: approximately 34 per 100,000 men and 12 per 100,000 women.

Half of NYC’s 2006 infections occurred among men who have sex with men (MSM), a group that has always been heavily affected by HIV/AIDS and remains at high risk. MSM of all races were affected, and new infections were evenly distributed among black, white and Hispanic MSM. But the new findings point to a generational divide. Blacks and Hispanics accounted for 77% of the new infections among MSM under 30, versus 59% of those 30 to 50. Two thirds of MSM infections occurred in the older group in 2006, but past analyses show that diagnoses in older MSM are declining while diagnoses in younger MSM are increasing.

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As expected, the new findings show that black and Hispanic New Yorkers were at greater risk than whites in 2006. Blacks, who accounted for nearly half (46%) of the city’s new infections, were infected at 3.5 times the rate of whites. Black men were especially hard hit, with an incidence rate of 231 per 100,000. Two thirds of the newly infected black men were 30 to 50 years old, but incidence rates were similar for black men over 30 (232 per 100,000) and those under 30 (210 per 100,000). Incidence was highest among those in their forties (330 per 100,000) and those in their twenties (291 per 100,000).

Hispanics, with 32% of new infections, had twice the incidence rate of whites. These discrepancies are narrower in New York City than in the U.S. as a whole, where 2006 incidence rates were 7 times higher among blacks and 3 times higher among Hispanics than among whites. But all three groups experienced higher incidence in New York City than nationally. Within New York City, whites were infected at 4 times the national rate, Hispanics at 3 times the national rate, and blacks at almost twice the national rate.

The new findings make clear that HIV is not just a concern for the young. Nearly two thirds of the city’s new infections occurred in people 30 to 50 years old. Nationally, people under 30 accounted for 41% of new infections, compared to 28% locally. Among black New Yorkers, people under 30 accounted for nearly half of new infections.

All New Yorkers can protect themselves and others from HIV

* Have one partner in a mutually exclusive relationship. This is the best protection against HIV and other sexually transmitted infections.

* Use condoms every time you have sex. Free NYC Condoms are available at many sites throughout the city. If you and your partner are monogamous, get tested before having unprotected sex.

* Avoid using alcohol and drugs when you have sex. Being drunk or high makes it hard to remember to use condoms.

* If you have ever been sexually active or injected drugs (even once), get tested for HIV. If you are at high risk of exposure to HIV, you should be tested at least once a year.

* If you’re HIV-positive, use condoms to protect yourself and others – and get regular health care.

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