There is a window period between the initial infection and when the test can reliably detect antibodies in the blood. For Zika antibodies, we recommend waiting for at least two weeks after initial infection. There is a small risk of a false-negative result with any antibody test, but especially if the test is taken too soon after infection. For real-time diagnosis in the early stages of infection, polymerase chain reaction (PCR) tests are more suitable.
Even with negative results, we advise practising safe sex for eight weeks for symptomatic women returning from an endemic area and three months for all men returning from endemic areas.
Antibodies produced by other similar viruses, such as dengue, yellow fever, and West Nile, can cross-react in Zika tests, leading to a false-positive result.
Zika antibodies reduce over time which can make it difficult to confirm past infections, especially if years have passed since the initial infection.