The basic principle of the HIV test is that it tests for antibodies that form to the infection with the virus. This is true of both the blood and oral swab tests. This test is quite sensitive and actually false negative are not much of a problem with the test (false positives are though). The only time that the antibody test is not completely accurate is in the first few weeks after becoming first infected with the virus because in the first few weeks the antibodies have not yet been formed. If you feel that you might recently have been infected, you should say this to your doctor
as a different test can be performed in this window of time. Fortunately, the flu shot
does not have any effect on the results of the test! As always the diagnosis and the management of your particular concern will require a physical examination by your personal physician. Setting up an office visit with your primary care doctor
if you still have questions might be indicated.