This Month's HIV/AIDS Facts

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Question: How long should I wait before being tested? What is the “window period”?

Basic Answer: Before getting tested, it is useful for people to wait three months from the time they think they may have been infected with HIV (the virus that causes AIDS). This is enough time for most people to develop antibodies to HIV (The average time is 25 days.) Otherwise, people may test negative even though they have HIV. This is called the "window period." People need to avoid taking risks related to HIV during the period before they are tested.

Detailed Answer: If people who have HIV (the virus that causes AIDS) know they are infected, they can take early steps to protect their health. Before getting tested, it is useful for people to wait three months from the time they think they may have been infected with HIV and avoid taking risks related to HIV during the period before they are tested. Most people develop detectable levels of antibodies to HIV within three months of becoming infected. The average time to develop detectable antibodies is 25 days.

The period between infection and the point when tests can detect antibodies is called a “window period.” This means that if people get tested during this period, their test results may be negative even though they have HIV. If people test negative but continue to take risks related to HIV (having unprotected sex or sharing needles and syringes with people who have HIV or who are unsure of their HIV status), they need to get retested every three to six months.

If people test negative, take no risks related to HIV, and then test negative again six months later, they probably do not have HIV. Stopping or reducing behavior related to HIV transmission can help people protect themselves and others from HIV infection.

SOURCES:

• Centers for Disease Control and Prevention. MMWR, 2001; vol. 50, no. RR-19. "Revised Guidelines for HIV Counseling, Testing, and Referral."
• Centers for Disease Control and Prevention. MMWR, 2001; vol. 50, RR-11. "Updated U.S. Public Health Service Guidelines for the Management of Occupational Exposures to HBV, HCV, and HIV and Recommendations for Postexposure Prophylaxis."
• DeVita, V., Jr., et al., eds. AIDS: Etiology, Diagnosis, Treatment and Prevention, 4th ed. 1997.

For current statistics, contact the CDC National AIDS Hotline (800/342-AIDS), Spanish (800/344-7432), TTY/TDD (800/243-7889); the CDC Voice and Fax Information System (888/232-3228); the CDC National Prevention Information Network (800/458-5231) or its Web site at www.cdcnpin.org; or the CDC HIV/AIDS Web site at www.cdc.gov/hiv/dhap.htm.