Get your Health question answered in 3 easy steps
A Doctor will be with you shortly
Ask a Doctor Now
175 Doctors are Online

What is the difference between third generation and fourth generation HIV test?

User rating for this question
Very Good
Answered by

General Surgeon
Practicing since : 2008
Answered : 1290 Questions
1.) What's the earliest a person can take a 3rd generation hiv test after havin unprotected sex & get a 95% accuracy rate?? 2.) What would the accuracy rate be at 25 days & at 27 days after havin unprotected sex? 3.) What's the differance between a 3rd & 4th generation hiv testing at 27 day after havin unprotected sex??
Posted Tue, 18 Feb 2014 in HIV and AIDS
Answered by Dr. Ashish Verma 4 hours later
Brief Answer: 3 months for 3rd gen, 1 month for 4th gen Detailed Answer: Hi, Thanks for writing to XXXXXXX This is Dr. Ashish Verma, a general surgeon, answering to your query. I will be answering in sequence wise as you had asked them: 1) To get a 95% accuracy witha 3rd geneneration hiv test, you have to wait for atlest 3 months, as the test detects antibodies, with takes about 3 months to show in blood. 2) the aauracy rate at 25-27 days will depend upon the type of test performed. Using a 4th generation test at this time will give you almost a 100% accurate results. But a third generation test will have a low accuracy. 3) 4th generation test has a window period of 11 days to 1 month, so at 27 days, their accuracy will be almost 100%. And as explained earlier, the window period of 3rd gen test is 3 months, so their accuracy will be quiet low at this period. Hope, that i have answered to all your queries. If you have further queries, i will be glad to answer them. Regards, Dr. Ashish Verma
Above answer was peer-reviewed by
Follow-up: What is the difference between third generation and fourth generation HIV test? 1 hour later
I was told by another doctor on this site that at 27 days the accuracy of a 3rd generation hiv test would be 95%... Furthermore, your body would start producing antibodies if infected by 20 days and beyond... Not sure which doctor to believe but I'm very nervous.. I took a hiv test at 25 & 27 days after having unprotected sex and it came back negative.. Really nervous about taking another 1...
Answered by Dr. Ashish Verma 1 hour later
Brief Answer: the accuracy at that time will be 90% Detailed Answer: Hi, Sorry for the discrepancies in the answers. Actually for third generation test: 90% people test positive in 4 weeks, 95% people test positive in 6 weeks, and 99.9% people test positive at 3 months, if they are infected. It does takes, about 3 weeks (20-22 days) for the body to start producing antibodies, to for them to reach to a detectable level it takes a few weeks more. But there is considerable person to person variation, and also depends upon the level of viral load in the source. I would suggest that you repeat the test after two weeks, if you are using 3rd gen tests. if you have tested with a 4th gen test at 27 days, and its negative, then there is no reason to worry. Regards, Dr. Ashish Verma
Above answer was peer-reviewed by
Share on Facebook
Share on Twitter
Share on Google+
Question is related to
Diseases and Conditions
Lab Tests
Medical Topics

The user accepted the expert's answer

Ask an HIV AIDS Specialist

© Ebix, Inc. All Rights Reserved.
All the information, content and live chat provided on the site is intended to be for informational purposes only, and not a substitute for professional or medical advice. You should always speak with your doctor before you follow anything that you read on this website. Any health question asked on this site will be visible to the people who browse this site. Hence, the user assumes the responsibility not to divulge any personally identifiable information in the question. Use of this site is subject to our Terms & Conditions
Already Rated.
Your rating:

Ask a Doctor