What does ‘indeterminate’ mean when testing for HIV?

If you have been tested for HIV infection, you may be told that the result is ‘indeterminate’, ‘equivocal’ or ‘invalid’. This means the test result is unclear. Another test needs to be done.

An indeterminate result means that the test kit shows a weak positive reaction, perhaps because of an unknown antibody cross-reaction, because of cross-contamination with another person's sample or because of another technical error. Indeterminate results can also occur in people following recent HIV infection, because their immune response is still developing.

If an indeterminate result is not reproduced in other tests, it is almost certainly simply a false positive reaction. However, if more than one type of test gives an indeterminate result, it will be necessary to retest with several types of test.

If results remain difficult to interpret, a new sample should be taken around two weeks later. If the cause of the indeterminate results was recent infection the tests should now give a more definitive answer.

Next review date