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HIV Window Period

Are your HIV tests accurate?

HIV testing may seem very complex.

This is greatly due to the testing ‘Window Period‘. That irksome time from when a person is infected to when tests can actually detect a HIV infection.

Click here to read about the Biology behind the Window Period

HIV Signs and Symptoms

The HIV Window Period and Test Accuracy

HIV PEP Post Exposure Prophylaxis

This has caused a lot of doubt and worry with regards to the accuracy of tests done.

You might even be wondering right now how accurate your tests are.

There is a lot of confusing information out there. Some people claiming a window period of 2 weeks some people even saying 10 years!

This is because HIV testing technology has developed significantly since HIV was discovered in the 1980’s.

So a lot of information out there is out-dated.

Also, not the same standard of tests are available everywhere. This has caused different governments and different health authorities to develop different testing guidelines. So the reason why the Window Period is different in Massachusetts is different from Singapore is not because humans in the US react differently to HIV compared to humans in Singapore. It is because of local guidelines.

So what exactly if the HIV Window Period?

It depends a lot on WHICH TEST was done.

The following graph was prepared based on the latest information on Testing for the Diagnosis of HIV Infection.

HIV Testing Window Period for various Tests

HIV Testing Window Period for various Tests

 

 

 

 

 

 

 

Some points to note:

1. If you are within the first 10 days of possible HIV infection (aka the Eclipse Period), don’t bother doing any tests. There are NO tests that are accurate.

NB: If you are within the first 3 days of possible HIV infection please see us about PEP.

HIV Prevention within 72 hours of exposure (PEP) – Click Here

2. At day 10, the HIV-1 RNA PCR can detect HIV Viruses in the blood.

Remember that the RNA PCR test has a high chance of giving a false positive result.

If the RNA PCR test gives a report of less than 5000 viral copies per ml, it is likely a false positive.

Click here for information on HIV RNA testing at our Clinics

Also, the viral load may drop to an undetectable level upon full sero-conversion.

This is because the body’s immune system may have suppressed the infection to a point where there is not enough HIV virus in the blood for the RNA PCR test to detect.

3. Between day 14 to day 20, the HIV P24 Antigen will start appearing in the blood. This can be detected with 4th Generation tests (aka Combo tests).

This is why, although the official recommended Window Period for the Combo Test is 28 days, we are very confident when a patient tests negative at 2 weeks.

Remember that the P24 Antigen level will peak at about day 28 and becomes undetectable at about 6 weeks from infection.

This does NOT mean the 4th Generation (Combo) test is inaccurate after 6 weeks because the Combo test also detects IgM and IgG Antibodies (See below).

Click here to learn more about the Combo Test at our Clinics

4. Between day 20 and day 23, the IgM Antibody starts to become detectable in the blood.

This is only detectable by 3rd and 4th Generation HIV tests.

This is the other reason why even though the 4th Generation (aka Combo) test is supposed to be conclusive at 28 days, at 3 weeks when a patient is negative, we tell him/her it is as good as conclusive.

5. Between day 28 and 48, the IgG Antibody starts to become detectable in the blood.

This is detectable by 1st, 2nd, 3rd and 4th Generation HIV tests.

This will remain detectable in the blood for as long as a person lives. Therefore, doing a Combo test not only detects HIV infections that occurred recently, it also detects infections from years ago.

Click here for HIV Testing FAQ

More things to note:

The recommended 1st line screening for HIV infection is the Combo test NOT the antibody test.

So when you go for a HIV screening test, you should be asking for a Combo test. Take note that in Singapore the Combo test costs more than an antibody test.

The essential thing to remember about HIV testing is to get the RIGHT test done at the RIGHT time.

Come see us for professional advice on which test you need to do.

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Your are welcome to visit Our Doctors at Our Clinics anytime during our opening hours.

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Call us at 63972095 now to book your treatment.

Feel free to email your queries, feedback and suggestions on what other topics you want to see in the comments section below.

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We are Open on Saturdays and Sundays.

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We have 5 locations conveniently located at Robertson Walk, Bencoolen Street, Novena, Scotts (Pacific Plaza) and Somerset (H&M)

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Email: doctor@drtanandpartners.com

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If you have any questions, visit our free online forum on sexual health, HIV and STDs.More on HIV symptoms.If you need a HIV test visit Our Clinics anytime during our opening hours. You do not need an appointment.Find out more about Anonymous HIV testing at our clinics.Can’t wait for 3 months to find out? Find out more about Anonymous Rapid HIV Combo test at our clinics.If you had a high risk exposure to HIV within the past 72 hours, you can take medicines to reduce your risk of actually contracting HIV. Find out more on HIV PEP Treatment.We are now open on weekends.Related Articles:HIV CMIA Test AccuracyHIV ELISA and ECLIA testGetting HIV from Oral SexMore on HIV symptomsHow long can HIV live outside the body?Erectile DysfunctionPremature Ejaculation

About Dr. Tan
Dr. Tan graduated from the National University of Singapore in 2001. His residency was in the two largest public hospitals in Singapore; Tan Tock Seng Hospital and Singapore General Hospital.

Find the profiles of our panel of doctors.

Consultation $20.00-80.00
Rapid test only $20.00
(not inclusive of test)
8am – 5pm $60.00
5pm – 9pm $80.00
STD screening
Standard HIV, Syphilis, Hepatitis B/C, Herpes Simplex Virus Type I and II $ 200.00
Male
Urethritis
Urine – Chlamydia and Gonorrhoea PCR, Monilia, Trichomonas, NSU, Mycoplasma, Ureaplasma, Urine Culture, Candida $ 280.00
Female
Urethritis and Vaginitis
Vaginal Swab – Chlamydia and Gonorrhoea PCR, Monilia, Trichomonas PCR, Gardnerella PCR, Candida PCR, Group B StrepNSU, Mycoplasma, Ureaplasma, Direct Microscopy, Candida, Vaginal swab culture $ 345.00
Comprehensive (Male) Blood – Syphilis, Hepatitis B/C, Herpes Simplex Virus Type I and IIUrine – Chlamydia and Gonorrhoea PCR, Monilia, Trichomonas, NSU, Mycoplasma, Ureaplasma, Urine Culture, Candida $ 390.00
Comprehensive (Female) Blood – Syphilis, Hepatitis B/C, Herpes Simplex Virus Type I and IIVaginal Swab – Chlamydia and Gonorrhoea PCR, Monilia, Trichomonas PCR, Gardnerella PCR, Candida PCR, Group B StrepNSU, Mycoplasma, Ureaplasma, Direct Microscopy, Candida, Vaginal swab culture $ 525.00
Individual STD Tests
Determine Syphilis test Rapid Syphilis Test $ 50.00
Determine Hepatitis B Test Rapid Hepatitis B Test $ 50.00
Herpes Simplex Virus PCR Herpes Simplex Virus Polymerase Chain Reaction (PCR) Test $ 190.00
Chlamydia and Gonoccocal PCR Chlamydia and Gonorrhea
Herpes Simplex Virus Type I IgG Antibody Herpes Type 1 $ 40.00
Herpes Simplex Virus Type II IgG Antibody Herpes Type 2 $ 40.00
Non-Specific Urethritis (NSU) Culture Mycoplasma, Ureaplasma $ 118.00
HIV test
HIV RNA/DNA Polymerase Chain Reaction (PCR) Test $600
Add $100 for expedited results
Rapid Fingerprick Blood HIV-1/2 P24 Antigen/Antibody Combo (HIV Duo Test) (4th generation!) $ 150.00
Rapid Oral Saliva HIV-1/2 Antibody Test (Oraquick) $ 50.00
Rapid Fingerprick Blood HIV-1/2 Antibody Test (Determine) $ 50.00
PEP $2000 – $2200

1,022 Comments

  1. Stabler

    Dear Doctor,
    Thank you for this helpful resource.
    I have a couple of questions regarding an exposure to hiv and the effect pep plays on test results. I am male had a potential exposure with a female of unknown status. Vaginal sex was protected but I performed oral sex (cunnilingus and vaginal fingering on her). She suffered cervical irritation and began to bleed so the sex was discontinued. Here in the UK I was prescribed pep at 30 hours post exposure. I adhered for the full 30 day regime. I tested negative at baseline, negative at day 31 (end of pep) and day 40 (9-10 days post pep). I was advised to attend the UK GUM clinic again at 12 weeks post pep (now).
    I am particularly concerned because at 14 days post pep I suffered from a very sore, stiff neck for 1 week. (No rash, fever, swollen lymph nodes or throat pain). The neck stiffness was the sort of stiffness I’d associate with accute meningitis. I researched this and found information from the Canadian health service advising that stiff neck is reported as a primary ARS symtom in approximately 30% of seroconversion cases. This neck pain was not posture related or related to muscular strain from lifting weights etc. It was a kind of discomfort and pain I have never experienced before, even during flu illnesses.
    My question to you, doctor, is how indicative would your clinic consider my negative tests at 31 days post exposure (end of pep) and 40 days post exposure (9-10 days post pep)? I realise I need to test again at 12 weeks post pep (this week) but I am so certain my test will be reactive I have completely lost the courage to revisit the clinic. (I should add that I suffer from extreme ocd/intrusive thoughts and anxiety disorder and bouts of ideation).
    Any input appreciated, particularly regarding the stiff neck and the reliability of the 40 day test. The tests were all 4th generation duo veinous lab tests (not rapid tests).
    Thank you, doctor

  2. Hi doctors
    I did test duo test ultra at 27 day after unprotected sex
    Do you think that is big difference between 27 and 28 days ?
    Thanks

    • Hi,
      There is not much difference but as we state above, at least 28 days post exposure will give the most conclusive results.

      • Sorry for asking again
        But my own doctors told me that i have to re-test after 3 months
        Do you think that is necessary?

        • Hi, it is our opinion that our Combo HIV test is conclusive after 28 days. You will need to discuss with your own doctors if they feel the need to re-test.

          • Sorry again
            My duo ultra test was in Turkey
            The test equipment is made by Biomerieux in France
            In the paper of my test written ( 4 jeneration vidas )
            Do you think that is sensitive test?

  3. Dear Doctor,

    I had an exposure wherein condom broke at the beginning of unprotected receptive anal sex. My partner had only managed to put the head of his dick in my anus and the duration of intercourse was no longer than 10 seconds. It was my first anal sex experience ever. I have been experiencing terrible anxiety ever since the sexual encounter happened and have not been able to concentrate on my work/life at all.
    Since I am flying to a different country after a week, I want to take the test on day 13.
    Would a duo test (that includes p24 antigen) on day 13 be any good indicator of my status? Or will it be just waste of time?
    I cannot take the test

    • Hi,
      Unfortunately, the combo test at day 13 is too early to be considered conclusive. I would advise you to check after 28 days.

  4. Anxiety

    Hi Doctor Tan,

    Thanks for all the good and hard work you have been doing. I have a question. I had an exposure with a poz CSW but protected sex only. I took SD bioline combo rapid test after 4, 6, 8 and at 9 weeks and all came back non reactive. Is it conclusive or do I need further testing again at 3 months? feeling like having ARS. Thank you!

    • In my opinion it is conclusive. However you should verify this with the doctor who did the test for you.

  5. Dear doctors

    I have an exposure with a girl.
    After we are done we are worried about each other hiv status. So we got ourselves check with SD bioline 4th gen duo test on
    2nd day after exposure – neg
    18th day – neg
    25th day – neg

    Do u still recommend to be tested on the 28th? and on 6week?

  6. Dear doctors .

    Is p24 antigen detectable by day 19 ? I read a article saying that it is ONLY 50 % accurate if a 4th gen duo test is done before 28 day.

    it’s says p24 will decrease after week 3 and 4 . It’s so contradicting if according to them by 3rd week p24 will decrease as antibodies is produced then how can p24 not detectable or not accurate on day 19 ?

    So to say the test for antigen is not sensetive enough ? Or the article is utter rubbish.

    Me and my partner got tested on day day 1 (baseline) and day 19 and is a solid negative using sd bioline duo combo 2.0

    Am having cough for 2 days and a slight fever 37.9 and some chills but I figure could it be cause by excessive smoking for the past 3 weeks ? Like almost 30 sticks a day .so starting to freak out again no rash or other symptoms.

    Will be doing 1 more on day 28 for sure . Just trying to figure it out to have a peace of mind . Please help me base on your professional opinion .
    Thank u very much .

    • In my opinion, the 4th Generation Duo test is conclusive at 28 days. I do not know the facts that the article you read used to make their conclusions. Perhaps you can ask the writers of that article.

  7. Two negative tests of 4 generation in lab at 13 and 26 days are good indicator? As good as conclusive?

    • Hi,
      Your tests are a good indicator that you are negative for HIV but it will also depend on the guidelines set by the manufacturer of your test kits. The 4th generation tests we provide recommend testing at 28 days post exposure for conclusive results.

      • I’m tested with SD bioline duocombo 2.0

        There is alot saying about the antigen some say peak at 20 days some says 28. Action for aides Singapore says 14 days is accurate. So that’s why I waited till day 18. So just to make sure abit

        • Hi,
          Yes, as you can see with your own research, guidelines do vary slightly. This is why we recommend 28 days to be absolutely conclusive.

  8. Hi doctors. I have a recent exposure with a girl 18 days ago. The next day we both get tested with 4th gen duo kit and both are negative. I did another test today at day 18 after our exposure and is also negative. I understand that this result is not conclusive but is it a VERY good indication for my hiv status?

    I read about the kit can also detect P24 antigen which will peak at around 21 days but could it be high enough to be detected by day 18?

    Thank you very much.

    • Hi,
      Yes it is a very good indication that you do not have HIV; however, the most conclusive result would be after 28 days.

  9. Dear doc. I have a unprotected virginal sex with a lady on 23 Feb 2017. I was prescribed PEP after 38 post exposure. I manage to get her to get tested 4 day post exposure and another at 17 days post exposure. Both by 4th gen SD bioline duocombo test both is negative. I understand that the results are not conclusive before 28 days but can it be a very good indication for it?

    I.did not do the test for myself because I’m afraid that Pep might affect the results.

    I would appreciate if u can let me know how indicative the result can be so to ease my anxiety for the past few weeks.

    I have test at base line and a comprehensive std test all also neg.

    Please help

    • Hi,
      If you are HIV negative at baseline then the accuracy of your partner’s combo test would be determined by her previous exposures, so testing her at ‘day 4 and day 17’ post-exposure in relation to your sexual act would not really be relevant. So, unless she somehow contracted HIV in the 11 days prior to your episode, I would say you are safe.

      • Hi Dr

        This is exactly what I’m afraid of the 11 days. So I did the test on 17 day should be able to detect antigen by then right?

        So it’s kinda closed the window period?

        • Hi,
          If that is your concern, then 17 days could still be too early to detect the antigen and we would recommend repeat testing after the 28 day window period for results to be conclusive.

          • Thank u Dr for ur help. Much appreciated. Just yo clarify that antigen can be detected ranging from day 14 to 21 days on average right before antibodies starts to form. So is 21 days test more indicative then the 1 on 17?

          • Yes, that is correct.

  10. hi doctor.
    i massaged by a masseure and she hand job me, can i be infected with hiv, at day 28, 80, 90 and 117 i did a test hiv 4th generation and resulth negative. i wonder if these things can be infected. need i do test agian?

  11. Hy had unprotected sex with a boy of unknown status after 4 weeks I started experiencing all the ARS symptoms including vomiting fever rash muscle pain mouth ulcers and chills
    My questions are
    1.had a duo test in south Africa at day 32 and day 47 in your opinion are they conclusive
    2.should I stop worrying about HIV and move on?
    3.should I test again after 3 months?

  12. michael1991

    Hi doc,

    Few question from me: im male and i did protected vaginal sex, but after ejaculation i felt my condom slightly loose up to half of my penis,and i have stitch tunnel on it due to ky circumcision 10 years ago. I did cmia test on day 43th and it came negative:
    1. Can vaginal fluid with hiv virus goes through stitch tunnel?
    2. Is my test conclusive enough?

    Im very stress right now because i feel a lot of symptoms (tonsil inflammation, swollen lymph etc)

    Please help answer. Thanks

    • Michael 1991

      1) Condoms do not protect 100% against HIV and STI even without breakage and slippage

      2) In my opinion , your CMIA (4th Generation) HIV test is considered accurate and conclusive at 28 days after exposure

      Please note that we are unable to verify the accuracy for your test. for that, Please ask the doctor who has done the test for you.

      However , I recommend you getting tested for STD as you had unprotected sex.

      please visit us for a formal consultation . click here for the location.

  13. Hy am from south Africa and had a high risk exposure with an HIV positive women and in that exposure I contracted syphillis from her so my question are. 1.is it possible to get syphillis and not HIV? 2.had a duo at 4 weeks and 6 weeks all negative are my results conclusive 3.would you say a 4 weeks duo is conclusive for a person who comes from west Africa were the are reported cases of hiv2? 4. Is it possible to experience ars symptoms 4 about 5 weeks n still test negative? N thanx in advance for the response

  14. 55th day after exposure, i took combo test. negative. is this conclusive? i got sore throat for 5weeks. tthank you Dr. Tan and Partners.

    • In my opinion your tests are very indicative that you are free from hiv. officially the testing window period for the combo HIV test is for 28 days.

      please note that we are unable to verify the accuracy for your test. for that, please ask the doctor who has done the test for you.

      Your sore throat may be related to other medical conditions.
      However , I recommend you also getting tested for STD if you had unprotected oral/penetrative sex.

      please visit us for a formal consultation . click here for the location.

  15. 55th day after exposure, i took combo test. negative. is this conclusive? thank you Dr. Tan and Partners.

    • In my opinion your tests are very indicative that you are free from hiv. officially the testing window period for the combo HIV test is for 28 days.

      please note that we are unable to verify the accuracy for your test. for that, please ask the doctor who has done the test for you.

  16. Hi doc,
    Today is 50th day after exposure to hiv virus thru sex. There was no penetration that time but i masturbate him, then touched his lips,i kissed him i forgot i have mouth sores. What test can i take to make sure im not infected. I am worried and paranoid. I cannot sleep at night, i cannot focus at work.thank you for helping.

    • There is low risk of HIV transmission from receptive oral sexual intercourse. However , factors that increase the risk of transmission includes : Mouth ulcers, gum disease , presence of blood and ejaculation.
      You can click here to read more on getting HIV from oral sex.

      However , I recommend you getting tested for STD as you had unprotected oral sex.
      please visit us for a formal consultation . click here for the location.

  17. dr. last december 08 i had sex with a travestite. i did passive (receptive). i did oral sex for a few seconds without a condom to the travestite. the travestite used condom at the time of penetration. at 12 days a idi a 4th generation hiv test with negative result. at 19 days i had a p24 antigen test with negative result. at 23 days i did a 4th generation hiv test with non-reactive result. at 29 days i have a 4th generation hiv test with negative result. at 41 days i did a hiv 4th generation test with negative result. at 48 days i performed a hiv test 4th generation with negative result, i need more test to rule out the disease ?, thank you

    • In my opinion your tests are very indicative that you are free from hiv. officially the testing window period for the 4th generation HIV test is for 28 days.

      please note that we are unable to verify the accuracy for your test. for that, please ask the doctor who has done the test for you.

  18. Dear sir i have a protected vaginal but unprotected oral sex with hiv posotive girl i dont know the condition of condom i got tested on 9 months of exposure by tridot antibody test is non reactive And again retest after 10 months of exposure by same kit tridot is non reactive i need further tests please advice me.

    • Based on your activity described, protected sex is considered a low risk activity for acquiring HIV.
      However, it is still encouraged to check your condom before using to ensure it contains no rips/breaks and it reduces the risk against HIV and other STIs.
      Condoms do not protect 100% against HIV and STI even without breakage and slippage.
      In my opinion , your tri-dot HIV test is considered accurate and conclusive at or after 3 months post exposure.

      Please note that we are unable to verify the accuracy for your test. for that, Please ask the doctor who has done the test for you.

      However , I recommend you getting tested for STD as you had unprotected oral sex.

      please visit us for a formal consultation . click here for the location.

  19. i went to SPA to massage the body and massage worker hand job me,can i affect hiv? i made 4th generation ag/ab cmia on day 44, 64, 91 and 96 all test negative. should i do test after 6 month again? or my result is conclusive?

    • In my opinion you were not at risk and your results are conclusive. However, I would remind you that we are not in a position to verify accuracy of test results. For that you need to talk to the doctor who did the tests for you.

  20. is 14 days RNA negative test conclusive ?

  21. Hi did a 4th generation duo test at 24 days post potential exposure, is that conclusive?

  22. Jonathan

    Very scared! Had protected oral for 1 minute, then protected vaginal with CSW for 10 minute. She provided condom, so I am afraid if there was a hole in it. Symptoms of mild fever, then sore throat, ear pressure, sinus pressure in face, congestion, postnasal drip at 20 days. Now having muscle pain in inner thigh up and down leg. And allergic reaction of 1 small bump/rash every time I eat something. Also a ton of eye floaters for past 6 days. Now day 52. Tested negative on 4th Gen Duo at 41 days. Is that conclusive? Or could it be false negative?

    • Your test result tells you that you do not have HIV. Please see a doctor to get your symptoms checked properly, especially your floaters. Eye floaters could be due to retinal detachment which is an emergency.

      • Jonathan

        Could the eye floaters be caused by sinus pressure around eyes and temples? I have had the sinus pressure ever since I got sick, which might have been caused by sleeping under AC. The fever and sore throat seem to have been correlated to the sinus infection. So the 4th Gen HIV1/2 Ab and Ag is conclusive at 41 days?

  23. Hi doc

    Pls would an antibody test at 4 weeks (combo) be affected by PEP

  24. Hi doctor,

    Last week i had protected sex with geylang street walker during sex condom broke after i finished only i came to know it was broken it was 2 mins intercourse , then I stopped sex and immediately went to clinic ForPEP they test me with P24 ag/ab it was negative then they started PEP within 2 hours of exposure, now i am taking doses properly ( truvada & isentress) I haven’t experienced any side effects so far, I worried about the possibilities of getting hiv pls advice me further and after 30day of post exposure can i take elisa and p24 test??

  25. had
    two exposure with different ladies. the first one was Sep . 3
    without condom while the second one was sep 28 with
    condom…. i had the following tests – sep 27 . Negative by
    using determine at hospital -Oct 17 . Negative by using
    determine at hospital – Nov 7 Negative by using determine at
    lab -Nov 21 positive by using uni gold and determine at lab –
    Nov 23 Negative by using determine at different lab -Nov 25
    Negative by using determine at one international clinic in my
    country. Nov 27 Negative by using determine at one of the
    must standard lab in my state.. December 12 also tested negative at the same place by using determine… Doctor what is my stand now, am i positive or negative pls?
    ur urgent respond would really help

    • I don’t know. You have had 1 positive test. In all likelihood this was a false positive. However, you need to see a HIV specialist for a proper workup for a false positive test. You need proper medical advice. Go see a doctor.

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