after an organ transplant) whose bodies might take up to 3 or 6 months to make
a detectable amount of antibodies. The CDC will recommend
a 3 month window period for
a number of reasons, one being that it will ensure that the test is accurate for everyone, including that small group of people who need to wait longer than 6 weeks.
The only STDs that are transmitted through blood-to-blood contact are HIV, Hepatitis B, and Hepatitis C.