Prepare for your IVF Viral Screen Blood Test by following these instructions. If there is a chance that you have been exposed to HIV, hepatitis B or C then please let us know how long before taking your sample this occurred. Your sample should be taken 4 weeks after any hepatitis B exposure. Take your test at least 4 weeks after any possible HIV exposure, a repeat test is recommended at 12 weeks. Do not take biotin supplements for two days before this test, discuss this with your doctor if it is prescribed. Please let us know if you have had a hepatitis B vaccination. You should wait at least two months after your vaccination before taking this test.