Why test for HIV?
When it comes to HIV disease, knowledge is power. HIV disease commonly involves a lengthy period - as long as a decade - between infection and the development of symptoms. People who know they are HIV infected can be monitored for changes in their condition and for possible treatment, even before symptoms appear.(1) Individuals who know they are infected with HIV can also aid prevention efforts by taking the necessary precautions to avoid spreading the disease through unprotected sex or sharing needles.
What do tests tell?
When conducted carefully, HIV antibody tests are highly accurate. The most commonly used tests measure antibodies developed in response to HIV infection. The ELISA (enzyme-linked immunosorbent assay) test takes only a few hours and is extremely sensitive in identifying positive results. Most testing protocols involve confirming the ELISA result by the use of a another antibody test known as a Western Blot.(2)
A window period exists between the time when an individual is infected with HIV, and seroconversion, or when antibodies to the virus can actually be measured. This window may be a few weeks or months; by six months at least 95% of infected individuals test positive by conventional HIV antibody tests. During the window period an individual is capable of transmitting the virus through unsafe sex or needle sharing.
Who gets tested?
Approximately a third (32%) of American adults have been tested for HIV.(3) Most are tested in health care settings, such as clinics, hospitals, HMOs or physicians' offices. Becoming a blood donor is still the most common reason for being tested. There is also a national network of alternative test sites where anonymous HIV testing is available. The number of tests conducted at these locations each year has grown from 79,000 in 1985 to more than two million in 1994.(4)
Slightly less than a third (30%) of adults who are tested seek testing solely to find out whether they are infected. Other reasons for being testing include: hospitalization or surgery (12%); application for insurance (16%); military induction (7%); referral by doctor, health department or sexual partner (7%); or for immigration-related reasons (4%).(3)
Who should be tested?
Ideally, those at risk. The National AIDS Behavioral Survey of more than 13,000 adults examined whether those at highest risk were using public programs for HIV counseling and testing. An "alarmingly high" proportion (more than 60% of those at highest risk) had not yet been tested for HIV antibody.(5)
There is a variety of reasons why not everyone at risk has been tested.(6) Some people may deny their potential risk, or may not have a regular source of health care, or may not know where to go to be tested, or may not want to find out the results. Others may be concerned about undesired disclosure of the test results.
The risk of HIV infection is not distributed evenly throughout the country. The routine screening of low prevalence populations continues to be controversial, as evidenced by debates concerning screening health care workers, hospital patients, and newborns.(7,8,9)
What are obstacles to getting tested?
The potential for discrimination continues to be a real threat, deterring some who might benefit from seeking HIV testing. HIV-related discrimination has been reported in the form of denial of insurance, housing, employment, and other private or public benefits.(10) Although much progress has been made in fighting discrimination, it clearly has not been vanquished. The federal government continues to deny HIV-positive individuals entry into the Peace Corps, the State Department, the Job Corps or the US military.
In some cases, the social fallout from HIV testing keeps some from seeking it out in the first place. In other cases, individuals who are tested for HIV antibodies do not return for their results. Approximately 37% of those who tested at publicly funded clinics in 1990 did not do so.(11)
Fears about discrimination and breaches of confidentiality must be kept in mind when devising systems of testing and screening.(12,13) To overcome barriers, HIV testing should be made available on a voluntary basis in a wide range of settings. Anonymous testing currently available at alternative test sites will continue to be attractive to many who may be at risk or need reassurance. Others may feel more comfortable being tested by a physician or at even at home (should this latter option become available).
Does knowing HIV test results change behavior?
Sometimes. Some individuals may find that knowing their test results may help bolster their resolve to practice safer sex, wishing to preserve their status if negative, or to protect their loved ones if positive.
In the aggregate, the evidence for testing's impact on behavior is mixed.(4) A major review of studies of HIV counseling and testing's effectiveness conducted by CDC researchers found that despite dramatic changes in sexual behaviors among gay men, the extent to which counseling and testing played a role in these changes is much less clear.(14) Conflicting results are also to be found in reviewing studies involving injection drug users and women facing reproductive decisions.
Some studies have shown behavioral changes following HIV testing and counseling, especially with both members of a couple. A program in Rwanda, Africa provided education and confidential HIV testing and counseling to all participants in a research clinic, as well as their sexual partners. Rates of new HIV infections decreased significantly in women whose partners were tested and counseled.(15)
Is testing enough?
No. HIV antibody testing and counseling by itself does not constitute an adequate HIV prevention response. Knowledge of HIV antibody status is merely one factor among many that contributes to risk behaviors. A comprehensive HIV prevention strategy uses multiple elements to protect as many of those at risk of HIV infection as possible. Greater access to information about HIV serostatus can be a useful personal and public health tool, but it is only one element of a comprehensive prevention program.
Says who?
Agency for Health Care Policy and Research (AHCPR). Evaluation and Management of Early HIV Infection. Rockville, MD: AHCPR Publication No. 94-0572;1994.
Janssen RS, St. Louis ME, Satten GA, et al. HIV infection among patients in US acute care hospitals: strategies for counseling and testing of hospital patients. New England Journal of Medicine. 1992;327:445-452.
Schoenborn CA, Marsh SL, Hardy AM. AIDS knowledge and attitudes for 1992: data from the National Health Interview Survey. Advance Data. 1994;243:1-15.
Doll LS, Kennedy MB. HIV testing and counseling: what is it and how does it work? In G Schochetman, JR George, eds. AIDS Testing. New York: Springer- Verlag;1994.
Berrios DC, Hearst N, Coates TJ, et al. HIV antibody testing among those at risk for infection. Journal of the American Medical Association. 1993;270:1576-1580.
Valdiserri RO, Holtgrave DR, Brackbill RM. American adults' knowledge of HIV testing availability. American Journal of Public Health. 1993;83:525-528.
Phillips KA, Lowe RA, Kahn JG, et al. The cost-effectiveness of HIV testing of physicians and dentists in the United States. Journal of the American Medical Association. 1994;271:851-858.
Lurie P, Avins AL, Phillips KA, et al. The cost-effectiveness of voluntary counseling and testing of hospital patients for HIV infection. Journal of the American Medical Association. 1994;272:1832-1838.
Bayer R. Ethical challenges posed by zidovudine treatment to reduce vertical transmission of HIV (editorial). New England Journal of Medicine. 1994;331:1223-1225.
Gostin LO. The AIDS litigation project: a national review of court and human rights commission decisions, part II: discrimination. Journal of the American Medical Association. 1990; 263:2086-2093.
Valdiserri RO, Moore M, Gerber AR, Campbell CH, Dillon BA, West GR. A study of clients returning for counseling after HIV testing: implications for improving rates of return. Public Health Reports. 1993;108:12-18.
Phillips KA. The relationship of 1988 state HIV testing policies to previous and planned voluntary use of HIV testing. Journal of the Acquired Immune Deficiency Syndromes. 1994;7:403-409.
Hirano D, Gellert GA, Fleming K, et al. Anonymous HIV testing: the impact of availability on demand in Arizona. American Journal of Public Health. 1994;84:2008- 2010.
Higgins D, Galavotti C, O'Reilly KR et al. Evidence for the effects of HIV antibody counseling and testing on risk behaviors. Journal of the American Medical Association. 1991;266:2419-2429.
Allen S, Serufilira A, Bogaerts J, et al. Confidential HIV testing and condom promotion in Africa. Impact on HIV and gonorrhea rates. Journal of the American Medical Association. 1992;268:3338-3343.
Prepared by Kathryn Phillips and Jeff Stryker
Reproduction of this text is encouraged; however, copies may not be sold, and the Center for AIDS Prevention Studies at the University of California San Franciso should be cited as the source of this information. For additional copies of this and other HIV Prevention Fact Sheets, please call the National AIDS Clearinghouse at 800/458-5231. Comments and questions about this Fact Sheet may be e-mailed to FactsSheetM@psg.ucsf.edu. ©1996, University of California