NYC health department talks of experiment for detecting virus within sevem days of infection
The city’s health department will pilot an innovative HIV testing procedure that has been shown to identify HIV-positive patients who incorrectly test negative using conventional testing methods. The procedure, called pooled viral load (PVL) HIV testing, has shown it can identify people who are newly infected, but whose sero-status has not yet been identified by conventional screens.
Test methodologies typically used, including the rapid OraQuick test, can fail because patients infected during a three to six week window prior to the test have typically not yet produced the antibodies such screens detect. Yet such individuals are already in an acute phase of HIV infection, in which they have exceptionally high levels of virus in their blood and semen, and can thereby spread the virus easily. People who have acute infection may be up to 1,000 times more infectious during this phase than at later points in time. Detecting these new infections is, therefore, an essential component of stemming the spread of AIDS.
When used in tandem with conventional testing, the PVL approach is demonstrably better at capturing acute infections, according to data from North Carolina, San Francisco, and other locations. The safety of the nation’s blood supply has long been monitored using related technologies.
The pilot program to determine if PVL can work in New York City will test volunteer blood samples from only one of the city’s 10 sexually transmitted disease clinics. North Carolina used samples from clinics across the state. San Francisco pooled blood from its single large public clinic, representing one quarter of clients relying on government-supported facilities. San Francisco officials expect to extend the program to its remaining affiliated clinics by the end of the year.
The question before the New York City health department is which high-risk community will be chosen to pilot the program? The health department initially proposed doing the pilot at its Chelsea clinic, but now says that may change. Nor has the department decided key operational issues such as how long the pilot will run, what date it will commence, or what number of blood samples will be needed to make the pilot a good model.
Dr. Antonio Urbina, medical director of HIV/AIDS education and training at the Comprehensive HIV Center at St. Vincent’s Hospital, was co-author of a July 17 editorial in The New York Times urging the health department to immediately implement city-wide PVL testing. He is concerned that limiting the study to Chelsea could produce unreliable results incorrectly showing PVL is ineffective across New York.
“Piloting this program in only one clinic may give falsely negative results and sabotage or delay establishing pooled viral load testing in all New York City clinics,” Urbina said. “What if they only pick up a few acute infections [in Chelsea]? Are they going to can the program [for the whole city]?”
The health department did not respond to questions asking whether or not PVL testing would be scrapped in New York City if the pilot program at one clinic fails to show that a significant number of HIV positive patients—first deemed negative by conventional tests—were only correctly identified using PVL testing.
In a July 18 press statement, the health department’s press office wrote “at this point, we are planning to pilot [pooled] viral load [HIV] testing at our Chelsea clinic; further expansion of the program to other STD clinics will be based on results of [the] pilot.”
When asked a month later why the program was not being implemented in African-American communities, where some of the highest infection rates have been found, a health department spokesperson said, “The location for the pilot program has not yet been finalized.”
Yves-Michelle Fontaine, clinical coordinator for substance use counseling and education at Gay Men’s Health Crisis, speaking from his own experiences, and not on behalf of the GMHC, said, “The pilot should be supported by the epidemiology. Look at the statistics telling us about the Bronx. People shouldn’t have to travel miles and miles to get access to the newest services.”
A GMHC spokesperson said the organization was not yet prepared to comment on the city’s PVL pilot program.
“I think it’s important that the health department include people of color communities, especially a pilot that targets black gay men, given the latest information coming out of the CDC,” said George Bouldin Gates, director of operations at People of Color in Crisis, a Brooklyn-based AIDS organization, referring to the federal Centers for Disease Control and Prevention.
Studies have shown that African-American gay and bisexual men have long had higher HIV rates than either Latino or white men who have sex with men. In June, the CDC released results of a study conducted in five cities, including New York City, that reported 46 percent of black gay or bisexual men in the study tested positive, compared to 21 percent of the white men. Two thirds of the black men who tested positive did not know they were infected.
New York figures, published in the Health Department’s April 2005 HIV Epidemiology Report, sketch the extent of an emergency among many groups in addition to gay white males, for 2003, the last reported year. There was a 13 percent increase in the number of AIDS cases from the previous year. Of those learning they had HIV for the first time, 25 percent had already progressed to AIDS. The largest increase of new AIDS cases occurred among Latina women, up 21 percent. Eighty-one percent of new HIV diagnoses and 80 percent of new AIDS diagnoses were among blacks and Latinos, according to the report.
Accounting for age adjustments, the highest death rate for people with HIV/AIDS was in East Harlem, with 40.4 deaths per 1,000 people; and Bedford-Stuyvesant-Crown Heights in Brooklyn with 38.4 deaths. Chelsea-Clinton’s death rate was 17.5. Chelsea, however, did report the highest number of new HIV diagnoses with 153.7 per 100,000 people in 2003. Central Harlem-Morningside Heights reported 133, and East Harlem, 132.3. If an adjustment were made for gender, Chelsea-Clinton would presumably fall well below other neighborhoods for the number of new HIV diagnoses among women.
The health department has not yet demonstrated what range of samples will be necessary to ensure a representative pilot or if one neighborhood alone is appropriate for studying a procedure critics are urging be available all over New York.
Paul Galatowitsch, an expert on organizational and institutional responses to HIV/AIDS and lead author of the Times editorial, believes that limiting the pilot program to one high-risk community in a single clinic is unjustified.
“Based on the North Carolina and San Francisco data, there is no scientific reason for New York City not to establish [PVL] testing in all [STD] clinics immediately,” he said.
New York’s health department would have to find additional funding to implement PVL HIV testing across the city and “no additional funds are expected at this time,” a health department spokesperson said.
Cost-effectiveness models cited by Galatowitsch show pooling methods cut the cost of testing and that stemming the spread of the virus saves lives and money. According to the May 2005 New England Journal of Medicine, researchers in North Carolina have shown that the costs of viral load testing can be cut from $90.00 to $3.63 per test, using PVL procedures. North Carolina has captured an additional six percent of HIV infections among persons at very high levels of infectiousness in the course of its two-year study. San Francisco, which has used PVL for 18 months, shows a 10 percent increase in the number of infections detected that otherwise would have been misdiagnosed.
To make viral load HIV testing less expensive, the blood from different patients is mixed together, or pooled, and then tested. If the collective batch tests negative, then each individual is deemed negative to a qualified degree of certitude. If the batch tests positive, then each sample is re-tested individually to find the infected patient. PVL reduces the window period of incertitude from between three and six weeks using rapid OraQuick and other standard tests, to between five and seven days. It is a procedure best used in tandem with conventional antibody screens.
Patients who get a standard HIV test at a clinic or counseling center in North Carolina, for example, submit a blood sample for additional testing. That sample is pooled with those of other patients and then, using a nucleic acid amplification technique, the batch is tested for the presence of HIV genetic material. If HIV RNA is found, each sample that composed the batch is tested individually to pinpoint the infected patient. PVL HIV testing searches for the virus, while conventional tests detect antibodies the immune system produces in response to HIV.
Currently, the city is largely dependent on rapid HIV testing, which tests for antibodies to HIV. Some medical professionals are troubled by anecdotal indications that their patients sometimes ignore admonishments that detecting acute HIV infection by standard tests is in no way guaranteed.
“People get a clean bill of health and they’re not thinking what’s happened in the last three or four weeks,” said Dr. Barbara Johnston, deputy director at St. Vincent’s HIV center, referring to the period of time in which a patient may have been infected, but for which the standard antibody screens can give falsely negative results anyway. A negative result can bolster a patient’s sense that he does not have HIV, and may encourage high-risk sex. Health department employees sometimes informally refer to a patient’s paperwork as “a license to fuck” when it reports a negative result.
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