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Did either facility perform a Western Blot confirmatory test?
If so, what was the result?
The usual testing protocol is to perform an initial test that is a screening test, such as an EIA or rapid test. The screening test is designed to be very sensitive, but not as specific. Therefore, if the screening test is negative, the negative result can be trusted without further testing. If the screening test is positive, then a Western Blot test is done as a confirmatory test. The Western Blot test is very specific. There are some conditions that can cause a positive screening test, but the Western Blot test will be able to determine if HIV is present. If the screening test is positive and the Western Blot test is negative, then the result is negative. If the screening test is indeterminate, either a repeat screening test can be done or a Western Blot test can be done. If either test is negative, then the result is negative. It is unclear to me why the first facility did not perform the next step, but since the testing at the second facility was negative, then the result is negative.
Of course, it is also necessary for a sufficient period of time after an exposure for any test for HIV to be accurate. There is a period of time after initial infection before antibodies can be detected, so testing should be done after a sufficient period of time.