Question
Why do I need to repeat a 28-day negative HIV test at three months?
16 September 2023. Related: All topics, HIV testing.
I don’t understand how if a 28 day Duo test when negative is conclusive, why does the information on i-Base say …
“As with antibody tests, a small percentage of people may have a delayed response to HIV so people using this test four weeks after any potential exposure are routinely recommended to confirm a negative result three months later.”
I was negative at 35 days and was moving on with my life until I read this,
please help.
Answer
Note: Since 2021, UK guidelines recommend that a negative result at six weeks using a 4th generation HIV Ag/Ab test does NOT need to be confirmed with a second test. Testing earlier than 6 weeks still needs a second test to confirm a negative result. The earlier answer is kept online to explain the complications of HIV teting. See https://i-base.info/qa/11844
……………
UK recommendations have changed several times on this question. In 2010 when this question was first posted, UK guidelines routinely recommended retesting so the i-Base information referenced this.
Since 2014, the guidelines change to only recommend retesting if this was linked to a high risk of HIV. (See statement below).
Updated guidelines also recommend not having to wait for 28 days before testing. Instead, it is better to test as soon as possible and then retest 4 weeks later. This change was important. It stops people worrying and might pick up early infections. Unfortunately, we still hear of clinics ask people to wait 4 weeks (or longer) before testing.
Even with tests that are incredibly accurate, health care workers have a duty to explain the best chance for a confirmed negative status. The reason for recommending the confirmatory test is two-fold:
- A small number of people have individual responses to HIV that may not be picked up by the test at 28 days. When the tests are approved, this is based on a panel of responses from an extensive store of timed blood samples. These show that some samples pick up a positive test result after only a week and some after more than a month, but that most are positive for the p-24 antigen at around 15 days. Some people may not produce enough p-24 antigen for the test to pick this up though, so together with the antibody response, the combined test are still more than 95% accurate at four weeks.
- The second reason relates to the possibility that someone who is not picked up, might put another person at risk of HIV. This duty of care should be explained when you take the test the test and are given the results. So although you have almost certainly not caught HIV, you should use condoms with sexual partners, until the confirmatory result.
I wish there was an accurate test at two weeks or one day, but there isn’t. The technology is more complicated than most people realise, and the concern for future transmission of HIV, however slight the possibility, is a professional health care concern.
Please don’t let this cause you stress, you are almost certainly HIV-negative, but this is the detailed reason.
BASHH/EAGA Statement on HIV window period
November 2014
HIV testing using the latest (fourth generation) tests is recommended in the BHIVA / BASHH / BIS UK guidelines for HIV testing (2008). These test for HIV antibodies and p24 antigen simultaneously. A fourth generation HIV test on a venous blood sample performed in a laboratory will detect the great majority of individuals who have been infected with HIV at 4 weeks after specific exposure.
Patients attending for HIV testing who identify a specific risk occurring less than 4 weeks previously should not be made to wait before HIV testing as doing so may miss an opportunity to diagnose HIV infection (and in particular acute HIV infection during which a person is highly infectious). They should be offered a fourth generation laboratory HIV test and be advised to repeat it when 4 weeks have elapsed from the time of the last exposure.
A negative result on a fourth generation test performed at 4 weeks post-exposure is highly likely to exclude HIV infection. A further test at 8 weeks post-exposure need only be considered following an event assessed as carrying a high risk of infection.
Patients at ongoing risk of HIV infection should be advised to retest at regular intervals.
Patients should be advised to have tests for other sexually transmitted infections in line with advice on window periods for those infections (see BASHH guidelines at: www.bashh.org ).
Note: This answer was updated in January 2018 from an original post from October 2010. The additional note was added in September 2023.
Hi,
I would appreciate your response to my below question.
i had un protected sex with a woman that I paid to have sex, that lady told me she never had unprotected sex before me with any body.I’m tested negative after 4 weeks (day 31). Now today thirty eight day (41) so i’m going to take HIV test after 42nd day i.e 43rd day for relief. But from start of third week i’m getting lose motion like two to three times in a day and mild pain in stomach. Also severe neck and head pain especially from my shoulder to neck and back head continuously still now. Initially 3rd week mild sore throat pain because of head pain and after that never had sore throat. Dr offered me to take Dolo 650mg for three days morning and evening whenever i take that tablet my head pain gone and comes back next day. From two days back i’m taking ashwagandha powder in milk and my lose motions gone. i do not have any fever, rashes on my body, checked my weight from 3rd week, 4th week, 5th week that is constantly 75kg not reduced nor increased, no vomiting and also not having any ulcers in my mounth. This is really scaring me. Please help me these are HIV symptom? and also help me out after how many days i can take hiv test for correct result. In future i will not do sex with any prostitute.
Hi VJ,
These medications and your diabetes would not affect the HIV test result.
Thanks
Thanks Sir,
One Last Question.I was detected with diabetes in October and so taking regular medicines for the same. Also for stress and pain in my neck I had taken one doctor’s help and he gave me some medicines which I am taking. Can these medicines affect my HIV results. Kindly do answer.
Regards,
VJ
These tests are very accurate. For more information about HIV test please follow this link. We are not doctors so I cannot tell you what is causing these symptoms, as I said before you will need to see a doctor about this. You can continue your sexual relationship with your wife without needing to worry.
Dear Sir,
Thanks for the reply. I just wanted to ask about the accuracy of the tests. The first test on 31st October was an ELISA test whereas the other two taken on 16th November and 1st December were DUO ECLIA tests. How reliable they are in India or in any other part of the world? More over as told by you that if the above mentioned symptoms are not related to HIV then could it be severe stress which I am going through since 15th October? Can I have my sexual relationship with my wife and leave all worries behind? Surely I’ll never ever even touch any other girl except my wife again. Thanks once again for the patient hearing and for replies. I have high regards for you through out my life. Waiting for the reply!!
Thanks and Regards,
You cannot get HIV by receiving oral sex, protected sex or fingering. You have had 3 negative HIV tests. You do not have HIV. You do not need to test again.
Your symptoms are caused by something other than HIV and you should speak to your doctor so that he/she can investigate further what is causing this.
Dear Sir,
I would really put this striaght in order to put my scenerio very clearly.I developed bad circle( i shoudnt say that though) i had pai women to have sex with me 5 times in past 4 months.Three occasions it was only blow job (only received)but no vaginal sex and more over its more than three months since those incidents happened I had done fingering though in the vagina.Now on 3rd October 2010 and then on 15th October i visited sex workers place once again and had taken oral sex(only receptor) without condom and then on both occasions i had protected sex.After 1 week i had experienced some rashes on my face which disappeared when i took help from skin specialist( in fact they were gone in 4 days time).But i have some rash bumps still on my face and on my arms though.I have severe pain below my neck region and mild sore throat.Some dizziness as well.That all i have as far as symptoms are concerned.I took three tests since last encounter on 15th October which are described as under:
1 ANTI BODY TEST on 31st October 2010 -NON REACTIVE
2 DUO TEST (p24antigen and ANTIBODY TEST) on 16th NOVEMBER 2010-NON REACTIVE
3 DUO TEST(p24 antigen and ANTIBODY TEST) on 1st DECEMBER 2010-NON REACTIVE
I had also experienced some pain in my legs and hands which are not there right now.Please Please any one in this forum help me.Its like a living hell and fear of HIV and death has a eventually gripped me all over.Waiting anxiously for the reply!!!! I am sure i’ll not be denied over my queries.My whole life and my family are in a disarray
Regards
The likelihood of getting HIV by performing oral sex is very low. If your test at 3 and a half months is negative then you do not have HIV. There is no need to worry.
Is there any need to test after performing oral unprotected sex? Should I move on if my test is negative after three and half months?
Yes, you do not have HIV. You do not need to test again.