Most of the discussion here on window periods and test reliability has referred to 4th generation HIV tests. I received an HIV-negative result from a 3rd generation MEIA test 45 days after a possible exposure. What approximate percentage confidence can I have in this result? Thanks and regards.
I don't follow the test "generations" especially closely. But even the earliest ("first generation") HIV antibody tests used in the 1980s generally are positive within 45 days. You can be over 95% confident in the results, maybe 99%.
When I was worried a few years ago I had been infected, I remember reading that if the immune system of an individual is compromised prior to an HIV exposure (by another disease, chemotherapy) that these were the people that it took a longer time to convert to positive. I think this may be where the original 3 to 6 month guideline came from. I am sure there have been a few individuals who were late for no apparent other reason, just freak occurrences.
Some labs in the US still use the 1st gen test but this test is much improved over the 1980's since the chemicals and methods used are much more advanced. Home access uses 1st gen but even with that test its only 5-7 days slower than a 3rd gen.
The generation is really irrelevant if you wait at least 6 weeks to test. If you are just in the process of converting, then it might make a difference but if you are ok at 45 days, then you are probably ok. You can always test again at 13 weeks if you want to follow official cdc guidelines, but you will likely be neg
A 4th generation HIV test is a procedure using a 3rd generation ELISA (or EIA) antibody test combined with a P24 antigen test. This allows for detection of HIV about 5 to 7 days sooner than by a 3rd generation test by detecting the P24 antigen.
As carnageofthepast notes, test generation is only an issue when you are very near the time of seroconversion. The average time to seroconversion is about 21 days, so you are well past that time period. Your negative test at 45 days is highly indicative that you are HIV negative.
Copyright 1994-2018MedHelp.All rights reserved. MedHelp is a division of Vitals Consumer Services, LLC.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. MedHelp is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.