Question

I would like to know what the window period for HIV is ? that is how long one has to wait before a blood test can be done?

Answer

The time that it takes for routinely performed blood tests to change from negative to positive can be up to three months. In this "window period" people can test negative on routine testing but still be infected. There are other tests that (in South Africa at least) are more expensive and measure the virus directly. These are positive within a few days of acquiring the infection.