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Ask Dr. K

I have been reading that hepatitis vaccinations can lead to false positives on HIV tests. I've read that it occurs most frequently in the ELISA tests. Would this also occur in the Oraquick tests provided in non-clinical settings? How long after vaccination would this cause a false positive or is this a permanent condition which would require a western blot to be done each time a test is done in the future?

Rapid point-of-care tests is with oral fluid are certainly a bit less accurate than conventional laboratory-based testing with confirmatory testing. That’s why the rapid tests are reported to patients as “preliminary positive,” and all require confirmation. Studies show that while rapid oral fluid tests are more prone to false positives, there is no evidence that such false positives have anything to do with hepatitis vaccinations or prior hepatitis infections. The problem with the Oraquick rapid test appears to be the test device and how close it is to its expiration date (older test, more likely to be associated with false positive). We did publish a report on influenza vaccination and increased risk of false positive HIV tests [Erickson CP, McNiff T, Klausner JD. Influenza Vaccination and False Positive HIV Results. N ENGL J MED. 2006 March;1422-1423. (Adobe Acrobat file, 2 pages)]

Only a physician can make a diagnosis, not a test. If the diagnosis does not make sense, it is always wise to get a second medical opinion.

For more information on Hepatitis and HIV, visit

To your health,
Dr. K

Last modified on Thursday, November 19, 2009.
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