Window Period


MSHC will only send negative HIV results by SMS. Other test results are available up to one week after the date of your test. We will call you with any positive result. If you do not hear from us, you can assume your result/s are negative.

What is the “window period”?

The window period is the maximum time it takes for the HIV blood test to give an accurate positive or negative result.   The window period is 6-12 weeks, depending on the HIV tests used.  The HIV blood test used at Melbourne Sexual Health Centre has a window period of six weeks. While “Rapid” HIV tests process the blood sample faster (a result is given within 2 hours of the sample blood sample being taken), they actually have a   longer window period than the blood test used at MSHC. 

Provided you have not had any risky sex (sex without a condom) in the six weeks leading up to your HIV blood test at MSHC, you can be confident that the result you receive (positive or negative) is accurate.

A test done today will NOT tell us anything about any possible HIV exposures from risky sex in the 6 weeks prior to the blood test being completed today.

A HIV blood test done during the window period may indicate a person does not have HIV when in fact they do have HIV. In the very early stages of HIV infection, the HIV blood test result may be reported as ‘Inconclusive’ which basically means the result is neither negative or positive. There is also a small proportion of people who will receive an inconclusive result even though they are HIV negative. When an inconclusive result is received, the HIV blood test needs to be repeated to clarify if someone is HIV positive or not.  

If you are concerned that you have been exposed to HIV through having risky sex (sex without a condom), you need to wait 6 weeks after the possible exposure to get an accurate HIV blood test result at Melbourne Sexual Health Centre. 

Window period and PEP

If you have taken nPEP (non-professional Post Exposure Prophiliaxis, or medication aimed at preventing HIV after an exposure), you will need another HIV blood test completed 12 weeks after exposure, as it may take the blood test longer to detect the HIV infection following nPEP treatment. 

What puts me at risk of HIV?
High risk activities for HIV include:
  • anal sex between men without a condom
  • unprotected sex with someone from a country where HIV in the community is common
  • sharing injecting drug equipment (gear)