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HIV P24 Ag/Ab Test, Duo Test, Combo Test at our Clinic

Updated information on Rapid Anonymous HIV Combo test at our Clinics. 


Info leaflet for SD Bioline Combo Test

Info leaflet for SD Bioline Combo Test

I have been getting a lot of question with regards to the Duo test or Combo test as it is also known as.

Let’s first get some basics right:

Duo Test = Combo Test = P24 Ag/Ab test

All these terms refer to the same thing. Basically it is a test that simultaneously tests for the HIV P24 Antigen and the HIV antibody.

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

The HIV P24 antigen is a small piece of protein that is found on the capsule of the HIV virus. When a person is infected with HIV, these bits of protein can be found floating in the blood. The HIV P24 test is a test that detects these bits of protein. This test was first developed as a HIV screening test but rapidly ran out of favor due to the development of more advanced NAAT tests. (For more details on NAAT testing please read: http://www.drtanandpartners.com/nucleic-acid-amplification-testing-naat/)The window period for P24 testing is also very small. This test alone is only accurate for between 3 and 6 weeks post exposure. So it is a test with very limited applications unless combined with the HIV antibody test. The presence of P24 Antigens in the blood indicates a recent HIV infection.

Click here for details on getting the Combo test at our Clinics

We all already know that the HIV antibody test becomes quite reliable at 4 weeks and as good as conclusive at 6 weeks. Although most health authorities still recommend a 3 months window period. So putting these 2 tests together gives you a very powerful tool to diagnose HIV infection in as little as 3 weeks. Personally I prefer to conduct the Combo test at 4 weeks because I believe that is when the level of P24 antigen peaks in the blood giving us maximum accuracy.

In our clinic, we use the SD Bioline Rapid HIV Combo Test 2.0. It is a rapid test that takes only 20 minutes for us to get results. We are also approved to conduct this test as part of the Anonymous HIV testing Program.

The test is conducted very much like the HIV antibody test. All we need is blood from a finger prick. (For more details on Anonymous HIV Testing at our clinic please read: http://www.drtanandpartners.com/anonymous-hiv-testing-at-our-clinic/)

SD Bioline HIV Combo Test showing a positive result (2 red bars)

SD Bioline HIV Combo Test showing a positive result (2 red bars)










SD Bioline Combo HIV test showing a positive result. Note the test line is very faint. This could be due to a very recent HIV infection or the test could be false positive (1% chance).

SD Bioline Combo HIV test showing a positive result. Note the test line is very faint. This could be due to a very recent HIV infection or the test could be false positive (1% chance).










Multicentre clinical trials have shown 100% sensitivity and more than 99% specificity.

This kit has been registered with Singapore’s Health Science Authority (HSA).

So the Combo Test has many advantages including:

1. Earlier detection of HIV infection.

2. Rapid (20 minutes)

3. Anonymous

At our clinic the Combo Test costs $150.

Click on the picture for the latest information on the HIV testing Window Period

Click on the picture for the latest information on the HIV testing Window Period










Click here for HIV Testing FAQ

More on HIV symptoms.

If you have any questions, visit our free online forum on sexual health, HIV and STDs.

Click here for Info on STD Symptoms in Men
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Click here to see the full range of our HIV/STD Services

If you need a HIV test visit Our Clinics anytime during our opening hours. You do not need an appointment.

We are now open on weekends.

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

Robertson Walk          6238 7810   map

Bencoolen Street        6884 4119   map

Novena                           6397 2095   map

Scotts                              6694 2348   map

Somerset                       6262 0762   map

Email: doctor@drtanandpartners.com

We are Open on Saturdays and Sundays.

Click Here for Contact Details, Address and Opening Times.

Related Topics:

Anonymous HIV testing at our Clinics

HIV – Understanding the Window Period

Cost of HIV/STD tests at our Clinics

Condom Broke

Getting HIV from Oral Sex

More on HIV symptoms

How long can HIV live outside the body?



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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.

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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
Urine – Chlamydia and Gonorrhoea PCR, Monilia, Trichomonas, NSU, Mycoplasma, Ureaplasma, Urine Culture, Candida $ 280.00
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  $188.00
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. Ron Artest

    Hello, I had a 6 month rapid test done with just one line after 5-7 minutes and the technician said it is negative. I noticed here however that you have to wait 20 minutes. Do you think I should retest? I had a high risk exposure but negative duo after 5 weeks and this was supposed to be the confirmatory test. Please advise.

    • drtan

      From my experience if a test was positive it would show within 1 minute. So 5 to 7 minutes is more than enough. However, the fact is tests should always be run according to industry recommendations. If the lab/technician running the test for you is not following guidelines, you should ask him why. As for whether or not you should retest, that is medical advice that we cannot give over the internet. Please check with your local doctor.

  2. Hi,

    I had unprotected anal sex with a guy on April 1, 2016. I took HIV duo test on 19th day i.e April 20, 2016 and tested negative. How good is this an indicator with regards to reliability of the Duo test and the concomitant window period?

    • Very good indication. Certainly more than 90%. Still test again at 28 days to be 100% sure.

  3. Hi doc!

    I had unprotected oral sex and deep kissing with a person that is HIV undetectable. I will just ask if my negative combo test at 26 days is okay?

    • Your risk is very low to begin with. Your test result on day 26 is as good as conclusive. If you are worried , repeat on on day 28.

      • Hi! Doc just want to update my status I had my test SD Bioline 4th generation antigen and antibody finger prick test at 5 weeks (today) would you consider this conclusive?

  4. Dear Doctor, Hope all is well. I did an HIV p24 ag & abs (HIV Combo) after 80 days from exposure and the result was nonreactive. Do I have to do another test after 90 days?? Thanks!

    • In my opinion you do not. However, I will remind you that this site is not for dispensing medical advice and you should verify this with the doctor who did the test for you.

  5. YourPatient

    Dear Doctor,
    Please forgive me on the thing I’m gonna ask. I went to your clinic to do combo test. I forgot to look at the kits. I’m pretty sure the kit will be used only once. Because i live in fear that makes me always worry too much. Can you save me from thinking nonsense if I ask is there any chance by mistake doctor reuses the wet tissue, tube or finger prick kit? If by accident we reuse which contains previous customer hiv blood, will it be a risk for me? Should i test again? Thank you Doctor and please accept my apology on this question

  6. Hi, would like to seek your opinion. It’s known that several guidelines have mentioned that a 3 month result for a 4th gen test is conclusive. However, looking at the CDC guidelines, it’s clearly stated that the guideline is for Laboratories and not the rapid kits. There’s also an exception note to say that there’s not enough information to determine if the guideline applies to the rapid kits. Does this mean that the rapid kits may not be conclusive after 3 months? Thanks!

    • The rapid kits are certainly conclusive at 3 months. Read the WHO guidelines.

  7. David Tan

    Hi doc, is there a possibly fact that on 31 days that 4th generation cannot detect the p24 antigen and antibodies because that are low? Because im tested negative on 31 days. Im afraid that on 31 days both the p24 antigen and antibodies are low to detect so therefore is not conclusive? thanks for the reply doc

  8. Hi doc. I recently went to one of ur clinic and took a ag/ab combo test. It is negative and is 31 days post exposure. Is it conclusive? Because i see that p24 antigen is always at 28 days. Is it okay to exceed abit? What if the test doesnt detect the p24 at 31 days and antibodies not yet created? Thanks for the queries.

  9. Is the rapid combo test the same as other clinic 4th generation test?

  10. I heard doctor tan said something about the alere rapid determine combo test.. I took it at 25 and 44 days after receiving a blowjob from a guy without condom and both times came up negative. Is it conclusive? Please tell me it is

    • By definition, the Combo test is conclusive after 28 days. So I would say your test is conclusive. However, there have been some concerns about the accuracy of the Alere Combo test. You should check with the doctor who did the test for you.

  11. Dear doctor i had protected sex with a prositube 55 days ago and i had did a hiv 1&2 combo test on 53days after exposure will it be accurate and after exposure 2days i also did a test i know it not conclusive and on 15days after exposure i did a rapid test 3rd or 4th i dont know but it was also negative and on 50days after exposure i ask the prositube is she had hiv or std she said she is healthy & disease-free. Just had full body medical examination done 2 weeks ago. Result was favourable s , should I believe?

    • Your post is a little confusing. From what I understand, you had a HIV Combo test at 53 days. In my opinion, that is conclusive. You should also get screened for other STDs.

  12. Hi Doctor. I had done HIV 1/2 Antigen / Antibody ( Elisa / EIA) test after 30 Days exposure. . Results = Non reactive. Is this conclusive ?


  13. Dear Dr.

    My Combo Ag/Ab 4th generation test results are Negative after exposured 22 days and 29 days. Is it conclusive? Do I need to re-test after 2months and three months?

    Thank you Dr.

  14. I did a HIV combi by roche at 22 days after exposure “receiving a blow job from a girl” the result was negative 0.224. How good the result is so far? Thanks

    • It is as good as conclusive but you may want to repeat one on day 28 just to be on the safe side.

      • Hi again, I repeated the HIV Combi test at 29 days and the result was negative with a COI 1.99 which is less than the 22 days test I did.
        1. Since it was recieving a blow job and negative after 29 days shall I consider it conclusive?
        2. Did you ever see a negative result change after 29 days ?

        Thank you

  15. Thanks Dr.
    My local Dr. gave me drugs for allery, but she said that if after 2 days the allegy not reduce so I have to stop PEP because allery may become worst. I am wonder that how can I stop PEP because it is so impotabt to protect me. Please could you advise. Thank you so much.

    • My lips, palate become red, pain, no vesicle. It is difficult to take food and swallow. Today I tested Combo after 22nd days after exposure, S/CO=0.55. I have just took PEP for 19 days. I really worry if I have to stop PEP at days 19 or 20 due to bad allergy. How is PEP protect me if I stop at 19 or 20 days?

    • The best thing to do is to consult the doctor who gave you the PEP so an alternative PEP may be given to you. The thing about drug allergy is that if you continue taking it, your symptoms may get worse and it may be life threatening.

      • My Dr. did not mention about aternative PEP, just stop. I am taking pep which including 3 types: Lamivudin 150mg, tenofovir disoproxil fumarate 300mg and Efavirenz 600mg. What drug is most possibility of allergy do you think? What is alter native drugs can you reccomment? It is so sorry that I am in Viet Nam so I cannot come to see you.
        Thank you.

        • It is impossible for me to comment on which drug is causing the allergic reaction. Unfortunately I cannot give medical advice on which drugs to use over the internet. It is best to consult your doctor again, or another doctor to get an opinion on this.

      • If tomorrow I can convince the girl to do Combo test after 24 days exposure and the result is negative. May I stop pep due to allergy without worrying?

        • Combo test at 24 days is as good as conclusive, meaning if it is negative, there is a very good chance that she does not have HIV. It is up to you whether you want to stop or continue.

          • Dear Dr.
            Unfortunately she did not agree to do Combo test. I have tried to took one more day PEP by yesterday while allergy seems not reduce much (not increase too). Today my Combo test at 24 days is negative. Is it as good as for conclusive to stop PEP.
            If I stop PeP after taking 21 days. How effect is PEP protect me? Still can protect me?

          • A combo test on day 24 is as good as conclusive. Whether or not to continue or stop, it is entirely your choice. I cannot give this sort of advice over the internet.
            PEP may not protect you entirely if you stop taking it prematurely.

  16. Dear Dr.

    I got sex with a girl for about 1 minutes on Oct 15, 2015. I have took PEP for 15 days started at 62 hours after exposure. I sent the girl to test Combo 4th generation after 5 days of exposure, the result is negative. If the Combo result of the girl after 28days is negative, is it means she has no HIV and i am safe? How is the PEP if I took at 62 hours after exposure. After taking PEP for 28 days, may I test Combo and the result is correct or not after PEP?

    Thank you.

    • Combo test on day 5 is not conclusive at all. If combo test on day 28 is negative, she most likely does not have HIV and you are safe. PEP is effective within 72 hours from exposure, so you did the right thing.
      You may get a combo test after you complete your PEP.

      • Thank you Dr. Sii Sik Liong.
        Now I am at day 20. May PCR test give a precise result?

        • RNA PCR can detect HIV after 10 days (from exposure). Therefore, day 20 is good.

          • Dear Dr.

            Before taking PEP my Combo test result S/CO =0.3. Today after 22 days exposure (still taki g pep)I retested and the S/CO =0.55. Why is the S/CO increase from 0.3 to 0.55, is this a problem? Is the result can be conclusive?
            3 days ago my lips and palate become swell and red, pain, no vesicle. It is a little bit better today. The doctor said it may be allergy or Hiv symtom? I am so scare, please give your comment. Thanks.

          • As long as the number within the limit of negative, you are safe. Do not worry about the change in the number.
            Your symptoms do not sound like HIV symptoms. Please complete your PEP, and get yourself a HIv combo test upon completion.

  17. Hi doctors, appreciate if you could reply on my previous queries. Tq.

    • Perhaps you could repeat your question. Thank you.

      • Dear Doctor,
        I would like to enquire something about HIV risk. 7 weeks ago I went to a massage centre in Malaysia for a 4 hands massage(2 ladies). I din’t know that these are dirty massage until the massagers offer sex services during the massage. They provided hard body to body massage to me nakedly and I refuse for further sex services immediately after they mentioned to me. I think they are most probably hiv+. I am worrying non-stop after the incident and think that they might intentionally passed their blood to my body cuts or scratches during the hard body massage as I have many cuts on my body due to mosquito bites. I had low grade fever starting from 5th weeks, average : 37.2c to 37.6c daily starting in the evening. I regretted a lot and swear that I will never visit any massage centre anymore. I have performed few tests as follow before the 3 months cut off period :

        1. Hiv duo ag/ab (10 days after exposure)
        2. Hiv finger prick rapid test (4 weeks)
        3. Hiv finger prick rapid test (6 weeks)
        4. Hiv duo ag/ab (50 days after exposure)

        All results came out negative, I am still paranoid for the final test in accordance with 3 months guideline . Could doctor please advise me whether my previous tests are conclusive or I must wait for 3 months to go on with my life?

        I sincerely wait for doctor answer, thanks.

  18. Hello doctor im from india 1 year ago i fingered a girl of unknown hiv status and i dont know that time i had cut on my finger or not. After 11 months of that incident i got negative cmia result should i retesr again and can hiv 2 transmitted through fingering

  19. Hello Dr,

    I am 29 yrs male. I had unprotected sex on 9th September’15 post that on 27th Day means 6th October’15 I had a Elisa Combo/Duo Test(Ab/Ag) which come as Non-reactive.
    So shall i need to take HIV test again?

    Pls help me.

    • Dr Elaine Loh

      Even at week 3 HIV combo is almost as good as conclusive. Of course it would be best to do another repeat test just to be absolutely safe.

  20. Hi Doctor,

    Does the negative result through Duo Ultra (ELFA) at 12 months interval after an fingering incident conclusive? Negative for HCV antibody also after 12 months

    any possiblities for late seroconvertion?


    • Dr Justin Sim

      Your tests will be conclusive. It is unlikely to see such late seroconversion.

  21. A few days ago , I had sex with a sex worker in Bahrain . Only for one time .First of all I don’t know the girls HIV status.I kissed her and also fingering then I try to put my penis on her vagina ,but due to not full erection it was not in vagina , then I rubbed my penis on vaginas lips (my forskin is pull back).Her vaginal fluid touches on my penis top urethra .Then I ejeculate on the top of her vagina without penetration.Now I am so warried that her vaginal fluid touches my penis top.
    After that I did Rapid HIV 1/2/O triline rapid test on 33,40,45 days which only show one line at C part no fainted or normal line on other place .
    Then I take a HIV ab/Ag Combo(CMAI) at a lab on 49 days . The result was 0.23 NONREACTIVE.
    Please dr. guide me to understand that . I am so scared . I also not doing any sexual activity with my Wife.
    Please help me ..that what should I do now and what is my chances to get HIV.

  22. Hello

    Is an rna pcr at 19 days combined with an antigen test at 26 days conclusive?

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