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Testing after finishing Pre exposure prophylaxis


I understand that testing 3 months after last dose of PEP is required for a conclusive results, but what about taking PREP? What's the window period while a person is taking prep?
I have been taking Prep for two months, and I have a 4th gen test negative 45 days after last dose of prep, and a 3rd gen test negative 12 weeks after last dose of prep. Can I consider this results as conclusive?


Hi and welcome to the Helpline,

Good question!

It's hard to say what the window period is whilst someone is on PrEP. Testing is usually done regularly for an individual on PrEP. It would be best to talk to and work with a healthcare provider when it comes to this.

In your case, you can consider your test results as conclusive. Once you are off of PrEP, you can go by the regular testing guidelines regarding window periods. For the 4th generation test, at 4-6 weeks after, 95% of infections are detected. With the 3rd generation test, at 12 weeks your negative result is considered conclusive.

Congratulations on your negative result! In future, if you do find yourself on PrEP again, it would be best to discuss testing concerns with your doctor.



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