HIV continues retreat in SF
by Matthew S. Bajko
This year marks a decade-long retreat in new HIV cases in San Francisco. Between 2001 and 2011 the city has witnessed a steady decline in new infections.
Ten years ago the city estimated that more than 1,000 people would become infected with HIV, the large majority of whom were gay and bisexual men. Now San Francisco health researchers estimate there are 736 new HIV infections each year, according to the latest HIV Consensus Estimates.
The number could actually be as low as 621 new HIV cases per year. Due to statistical uncertainty, researchers in the city's Department of Public Health Epidemiology Section advise that the "plausibility bounds" for new infections range from 534 cases at the low end to 977 cases at the upper end.
The city's HIV incidence rate now stands at 0.09 percent, a 30.8 percent reduction in the rate since 2006. The city has also seen a 24.6 percent reduction in the number of cases over the last five years.
Dr. Grant Colfax, the city's director of HIV prevention, said health officials remain "cautiously optimistic" that HIV cases are in decline. He said the city still has an HIV endemic rather than an HIV epidemic, meaning rates of infection remain stable rather than rising upwards.
"We can't conclusively make the case that HIV rates are declining. We are still in an endemic state at this point," said Colfax. "There is still much work yet to go."
If the declines continue, it could bode well for the health department's HIV prevention section reaching its goal of a 50 percent reduction in new HIV infections, especially among gay and bisexual men, by 2017.
The majority of San Francisco's new HIV cases remains among men who have sex with men. It is estimated that 585 gay and bisexual men will become HIV-positive this year, the bulk of whom are likely to be in their 30s.
Another 49 gay and bisexual men who use injection drugs are expected to contract HIV this year. In total, there are an estimated 15,873 gay and bisexual men living with HIV in the city.
The HIV incidence rate among MSM who do not inject drugs stands at 1.27 percent based on a population of 59,809. The city's HIV prevalence among this population is at 22.7 percent.
Health officials believe a variety of factors are leading to the continued downward trend. For one, while the city continues to see spikes in STDs, including syphilis, HIV-positive men account for a large portion of the cases. Combined with their continued adoption of sero-sorting, where HIV-positive men seek out other HIV-positive men as their sexual partners, the STD infections are not causing a spike in HIV cases.
Another likely factor is the health department's policy of recommending HIV-positive people begin treatment early. It is believed to have led to less viral loads among at-risk populations, reducing the risk of HIV transmission between sex partners of sero-discordant HIV status. Researchers are currently studying the policy's impact to verify those claims.
"We are seeing a lot of benefits from that," said H. Fisher Raymond, director of HIV bio-behavioral surveillance in the HIV Epidemiology Section of the AIDS Office at the health department.
A third reason could be the fact that less gay men are moving to San Francisco in general, or, once they test HIV-positive elsewhere, they no longer feel the need to relocate to the city. Thus, they are not driving up the city's HIV caseload. And among those people newly arrived to San Francisco, they are not accounting for a large number of HIV cases.
"Newcomers being at risk didn't seem to hold up," said Raymond of the long held belief that recent transplants to the city had a greater chance of becoming HIV-positive. "As for positive people coming to San Francisco for services, that might have happened early on in the epidemic. But there is less migration now; the days of the gay ghetto are over."
In fact, Raymond said he suspects the reverse may be true. As the city's AIDS and HIV population ages – the majority of new AIDS cases are now among people 50 and older – they are retiring to other areas such as Palm Springs or Sonoma County.
"I do think there is an exodus of older people. That is why Sonoma is asking why their HIV prevalence among MSM is rising," said Raymond. "Well, the guys are old enough to buy a home, live in Sonoma and retire there."
The city continues to project it will not see any new HIV cases among newborns or people given blood transfusions, though there are 57 people living in San Francisco who acquired HIV either as infants or from infected blood.
The total number of new cases among straight men and women, including injection drug users, is estimated at 69. There are 2,012 heterosexual people living with HIV in the city.
Transgender women, including injection drug users, are expected to account for 32 new HIV cases. There are 583 transgender women living with HIV.
Overall, the number of people living with HIV in San Francisco is now believed to be 18,576, which results in an HIV prevalence rate of 2.27 percent.