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Why can HIV antibody tests be negative soon after infection?
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AIDS
Scanning electron micrograph of HIV-1 virions (green) budding from a cultured lymphocyte. Multiple round bumps on the cell surface represent sites of virion assembly and budding.
Standard HIV antibody tests can be negative shortly after infection because the body’s immune system requires time to produce a detectable level of antibodies in response to the virus.12
While the virus may be replicating rapidly during the primary stage of infection, these antibodies generally do not reach levels high enough to be identified by standard screening tests until a few weeks after the onset of acute illness. Consequently, there is a window of time following exposure where an individual may be infected, yet test negative for HIV antibodies.21
For those who require detection shortly after potential exposure, polymerase chain reaction (PCR) tests are an alternative option, as they screen for viral RNA rather than antibodies.1