[Question #3285] Window Period HIV Test

90 months ago

good afternoon experts

Years ago, they've always said here and on Medhelp that a 4th generation HIV test is conclusive after four weeks.

Now they say this test is conclusive after six weeks!

Why this turnaround?

What is the official policy in the US for safely excluding HIV with a 4th generation lab test?

H. Hunter Handsfield, MD

90 months ago

Welcome back to the forum. You were one of our first customers, with question no. 39! Thanks for your continuing confidence in our services.

We have explained this several times on the forum. (Sorry the search function isn't very sophisticated. That will change with new forum software in the not too distant future.)

New data became available, that's all. Our opinions and advice always are based on the best available science, and scientific data often are not static as new research is done. A published review of all the available HIV tests (https://www.ncbi.nlm.nih.gov/pubmed/29140890) included data that in 1-2% of cases, it takes 6 weeks for the antigen-antibody (4th generation) HIV blood tests to be conclusive, and CDC published an accompanying ediorial that endorsed that conclusion (https://www.ncbi.nlm.nih.gov/pubmed/29140891). There is no "official policy in the US", but the CDC recommendations usually are highly respected. At that point we revised our advice accordingly.

Be clear: in the vast majority of cases the AgAb tests are conclusive at 4 weeks. But for especially high risk exposures, a 6 week test is recommended.

I hope this information is helpful. Let me know if anything isn't clear.

HHH, MD

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90 months ago

Many thanks to Mr. Handsfield for your information.

I have often read on poz.com and thebody.com, there is always written by 13 weeks for a safe exclusion of an infection.

I have read your articles from the mentioned links, are understandable and reassuring.

Next I have read following work of Taylor D. et al, which supports your statements. (https://www.ncbi.nlm.nih.gov/pubmed/25033879)

Around the world, there are many different guidelines for this window period.

I now trust these six weeks. Also Mr. Pietro Vernazza (infkt.ch) has confirmed that to me.

Wish you a good time, friendly greetings.

H. Hunter Handsfield, MD

90 months ago

Nice summary. My only comment is that any site or service that still promotes 13 weeks is behind the times. It simply isn't necessary to go that long, unless for some reason testing is done with older (2nd genration) tests.

Thanks for the thanks. Take care and stay safe.

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90 months ago

hello mr. MD H.H.H

did you see the brand new entry on the CDC web page? ("how soon can clinicians rule out infection?")
Now they also write that a 4th generation HIV lab test is final after 45 days?

https://www.cdc.gov/hiv/testing/clinical/index.html

H. Hunter Handsfield, MD

90 months ago

That's the same information and resource I referred to above. (I cited a published CDC report instead of the website.) On this forum we round it off to 6 weeks. There is no statistical difference between that (42 days) and 45 days. Of course you or anyone else is free to keep testing beyond these limits if they wish.

That makes two follow-up comments and replies included with each question and so concludes this thread. I hope the discussion has been helpful. Best wishes and stay safe!

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