I had a possible HIV/HCV exposure.

Tests performed:

• 8 months after exposure: HIV-1 RNA Viral Load, HIV Ag/Ab, TP-Ab — all negative

• 8 months + 1 week: HCV Ab, TP-Ab, HIV Ag/Ab — all negative

• 8 months + 3 weeks: HCV RNA, HIV Ag/Ab — all negative

About 2 hours before these tests, I took 150 mcg of biotin (D-Biotin) from a multivitamin (https://iherb.co/KGWboLqB). I read that biotin can sometimes interfere with immunoassays.

My questions are:

1. Could this biotin affect RNA PCR results, or only Ag/Ab tests?

2. Are my results conclusive for ruling out HIV, HCV, and syphilis, or do I need any further testing?

Thank you very much for your help.

Thank you again for your earlier reply. From your explanation, I understand that HIV RNA PCR cannot be affected by biotin at any dose, and I believe this also applies to my HCV RNA test. Therefore, both my HIV RNA and HCV RNA results should be reliable and unaffected by any biotin intake—am I correct?

I also understand that Ag/Ab or antibody testing is not affected at the dose I took, which I forgot to mention in my initial question. After reading the HSA Singapore alert noting that doses ≥150 mcg may affect some immunoassays https://www.hsa.gov.sg/announcements/safety-alert/biotin-interference-with-clinical-laboratory-tests, I did a follow-up retest at 9 months, abstaining from biotin for 114 hours. HIV Ag/Ab, HCV antibody, and TPHA were all negative.

Given this, I wanted to confirm whether my earlier tests—taken after 150 mcg of biotin—can still be considered fully reliable.

Thank you very much for your guidance.

Thank you again, Dr. Handsfield, for your patience and guidance. For reassurance, I would like to confirm one last point.

In addition to the 150 mcg of biotin contained in my multivitamin, I've also been taking atorvastatin 20 mg, folic acid, an iron supplement, and a combination of vitamins and minerals including A, E, B6, K2+D3, zinc, and selenium. I also use omega-3 fatty acids, CoQ10, PQQ, and shilajit. From what I have read, none of these medications or supplements are known to interfere with HIV Ag/Ab, HCV antibody, syphilis (TPHA/TP-Ab), HCV RNA, or HIV-1 RNA testing, and I just want to confirm that this is correct?

I also want to mention the timing of my vaccinations: I received my third HPV vaccine and a Hepatitis A vaccine exactly one day before my 8-month HCV RNA and HIV Ag/Ab tests. One week after vaccination, I repeated HIV Ag/Ab, HCV antibody, and TPHA after being off biotin for 114 hours, and 18 days after vaccination I repeated my 9-month (HIV Ag/Ab, HCV antibody, RPR, HBsAg, anti-HBs, HSV-2 IgG) after 15 days off biotin. All results were negative.

Am I correct that neither these supplements nor the vaccines — even when vaccinated just one day before testing — could interfere with any of my test results, and that all of my results remain fully reliable and conclusive?

Thank you again for your time and reassurance.