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HIV – Understanding the Window Period

Asian Geographic article on HIV

Asian Geographic article on HIVThe HIV window periodoften is the cause of a lot of confusion.

There is a lot of information on the web throwing up numbers like 3 months, 6 months even 1 year. So what exactly if the HIV window period?

To better understand this, let us take a step back in time to when HIV was first discovered. At the same time, learn a little about how our immune system works.

The HIV virus was discovered in 1983. Prior to that, it was not known what was causing the disease known as AIDS that was ravaging certain communities in the world.

After scientists discovered the existence of the HIV virus, they had to find a way to determine if a person has this virus in his body or not.

The ELISA Test and Our Immune System

In 1985, they developed a test called ELISAwhich is based on a very basic principle of how our immune systems work.

When our body is attacked by a virus, it will produce anti-bodies to fight the virus. Anti-bodies are unique. The anti-bodies used to fight HIV would be completely different to the ones used to fight dengue, for example, or any other virus.

So finding HIV anti-bodies in the body is indirect evidence that there is HIV virus in the body too. The ELISA test does exactly that. It tests for the presence of HIV anti-bodies. HIV rash

Imagine each virus infection is a fire that starts in the body. Each of these fires produces a uniquely colored smoke. When we see a particular colored smoke, we assume that there is that particular type of fire burning away. The ELISA tests for HIV colored smoke but does not detect the fire itself.

But there was one big problem. It sometimes takes the body a long time before the body produces enough anti-bodies to be detected by the ELISA test. In other words, the fire has to burn for a long time before it produces enough smoke that can be detected by ELISA.

This period when a person is infected with HIV and the ELISA test is unable to pick it up (the period when the fire is burning but there is no smoke) is called the window period.

This was correctly recognized to be a very important finding and rightly so because a person infected with HIV within the window period can get tested and be told he does NOThave HIV. He will then not take steps to protect himself and the people around him thus increasing the risk of spreading the disease.

Different Types of HIV Tests

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

Scientist has ever since been working on improving and coming up with new and better testing techniques and technology. There are now multiple different tests for HIV including ELISA, ECLIA, CMIARapid HIV Tests, Western Blot, RNA PCR, DNA PCRand P24 Combo Tests.There are also multiple different manufacturers of each test. All of these tests have their own rates of accuracy, window periods and applications in the management of HIV. To make things even more confusing, there are also tests for indirect evidence of HIV infection like CD4 cell count and CD4 CD8 cell ratio.

So when you read somewhere or someone tells you that the window period for HIV is X number of months, your next logical question should be ‘by using which test?’ – HIV Test Singapore

To know which test done when has what accuracy requires a lot of professional knowledge. This information is also constantly changing as more and more research information is published. There are also other considerations such as waiting time, anonymity, costs etc

It is still best to speak to Our Doctors who are certified and trained in HIV counseling and testing to find out which test is most appropriate for you. Anonymous HIV Testing

Click here for Updates on the HIV testing Window Period

One thing remains constant. If you are at any risk of HIV at all, no matter how minute, you MUSTget tested. But as for which test to do and when to test, it is still best to speak to a medical professional trained in HIV matters.

Click here to learn about the Different Generations of ELISA

The HIV Window Period and Test Accuracy

HIV PEP Post Exposure Prophylaxis


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  1. Hello i had a HIV RNA test and my result was ” not detected” 18 days after my exposure …is it conclusive??thanyou for your reply doctors ..Godbless

    • I would consider it essentially conclusive. Although by strict guidelines RNA testing is not recommended as screening, and you would be advised to do a 4th generation combo test at 28 days of later.

      • Hello dear please help me. I have handjob with hiv positive person she has cut on her hand i have also cut on my penis please tell me i am on risk. I have done hiv combo test after 32 days 84 day and 120 days all came negative. Please tell i nead futher testing.

  2. Am circumcised and had protected sex with a woman but later removed the condom and ejaculated in her a min after entering her. After 3 days i tested her and the results were positive and i came out negative. After worrying and researching about HIV i got so worried and scared and couldn’t sleep that night. the following day i started experiencing the symptoms. Had a mild flu,mild headache though maybe just 1min and am fine. Started feeling weak and lost a bit of appetite. Yesterday was the 12th day and i felt like i was developing sores in my mouth,i took nystatin oral n today am better, just feeling them a bit. I also had a sweaty night. My temperature is normal at 36.7c. Am stil scared such that i spend not of my time researching on the internet about HIV. What are the chances of me being infected and can symptoms start at 4 days after exposure? Am so so scared. And are the symptoms usually mild or what? Due to fear i did a test with SD biolin 3.0 it came out negative though i know this is very far from being conclusive.

    • It is highly unlikely to develop any symptoms like that within the first 1-2 weeks. Please perform the appropriate testing after the window period for conclusive results.

  3. Dwi Nanda Listya Utama

    I was wondering if you guys could inform me on what the hiv ars rash looks like. I’m asking because I have these small red itchy bumps on my right arm. It starts with one small bump at my arm and goes down to the middle and the left arm about 2 days after the first one. It’s like 12 of them, not grouped together but it located in different areas included two spot in my thigh. It’s really itchy so I’ve been putting itch powder and cream on them.

    Thanks in advance for all of your help.

    • There is no typical description of the rash – it can vary a lot. If you are concerned, please do visit us for a proper evaluation and testing if required.

  4. Hi sir. I am sex with a hiv positive girl. Single exposer but my test result are all negative. Ofter 15 months hiv rna pcr qualitative, hiv alere combo, western blot, elisa,tridot all are negative. But I cannot accept my result. I am dedaly worried pls. My test result ofter 15 months today elisa hiv, hbsag ,hcv, vdrl all are negative. Pls clarify me sir any further test needed. I am 100% negative or not.
    One doctor told me hiv ofter 5 &6 years become positive it is true….

  5. Doctor,
    Is window period of 4th gen test same for both hiv 1 and hiv 2.as i understand p24 antigen is only present in case of hiv 1.does my 55 day non reactive result also cover hiv 2?please tell.thank you in advance.

  6. Good day doctors!

    On 6 Jan wee hours i visited a massage parlour in JB for hand job service. During this transition, I did fingered her. Upon ending, she used a wet tissue to wipe my finger and then proceed with the same contaminated tissue to wipe my penis which I then proceed to the bath room in less than a min to clean off myself.

    I am worried with this exposure even though hiv risk is low. I took the 4th gen combo test on 26 Jan noon time which came out to be neg. Is this conclusive at day 20 to spot ag? Do i need a retest @ day 28? Also flu like symptoms from 20th Jan till today.

    Lastly, I would like to visit your clinic for syphilis and herpes test due to the above exposure even though no symptom of std in me.

    Thank you for your time!

    • I would consider your exposure risk to be essentially zero. The test is not considered conclusive until 28 days post-exposure (assuming an actual risk exposure). Please visit us for a proper consult and testing as appropriate. We do perform syphilis and herpes testing as well.

  7. The INSTI® HIV Self Test claimes to be potentially effective at 21-22 days (but not conclusive untill 3 months)

    Is there any data on how effective it is at 21-22days. I took a INSTI® HIV Self Test at 30 days post exposure that came back negative.

    I will follow up with additional tests I just want to have some idea how effective it is at this stage?

    thank you

    • I am not able to comment on home testing kits. Please visit a health care facility for proper testing at the appropriate time.

  8. daily ur reply all the person questions y not for me.
    I am waiting your replay pls sir……
    Thank you advance…….

  9. Plz reply me doctor your silent I’d killing me daily ur reply all the person questions y not for me

  10. Dear Sir,
    I had unprotected vaginal sex with a woman. Later on 8 months I found out she had HIV.
    1).What are the chances a single exposure hiv transmission.2).ofter 8 months hiv westren blot negative.3).ofter 1 year hiv elisa test also negative.
    4).ofter 1 year hiv,hcv,hbsag,tpha,vdrl antibodies test are all negative.5).Does it mean I can forget about it and go on with my life?6).iam move on my wife with out condom?
    iam fully worried iam infected with hiv or not. pls iam fully confused clarify me one by one pls sir…
    i hope your clarify my confusion….

    Thank you….. in advance ……….

  11. Hi,dr I have protected sex with a sex worker after 33day i have hiv 1/2antibody/antigen p24 test is no reactive is that mean I am hiv free? The test is call western blot is that 4th generation?

  12. Hi,doctor hiv 1/2 antibody&antigen p24 is that 4th generation? And is that if I tset negative that mean I hiv free ?or need to retest again?

  13. Dear dr
    If I want check std and hiv need how long window period and the cost is how much?after sex with sex worker I have sex with my wife with condom can transmission to my wife?

  14. Dear dr
    I have protected sex with a sex worked about 15 min halfway the girl give me unprotected hand job and carry on with condom sex
    Now what can I do dr
    Can i have protected sex with my wife? At malaysian eclia is 3th generation or 4th generation?

  15. Dear dr
    I have protected sex with a sex worked about 15 min halfway the girl give me unprotected hand job and carry on with condom sex
    Now what can I do dr
    Can i have protected sex with my wife?

  16. Hi Drs!
    I had a 4th generation test done on the 27th day after possible exposure in the infectious deseases centre of the hospital. They told me that it was accurate and definitive at 1 month after possible exposure (so 4 weeks, 28days as you state also). My question is: can I class my test definitive or does one day makes any difference?
    Thanks in advance for your amazing service here

  17. Hello from the UK. I had unprotected sex with a lady and had a 4th generation test at 32 days which came back negative.Should i have another one at 3 months or is this conclusive?. Sorry to ask but there is so much conflicting information on the internet. Many thanks for your time and expertise.

    • We are very happy with calling a 4th gen test conclusive at 28 days or more, which is in line with WHO guidelines. However, it is always best to clarify with your own doctor regarding local guidelines.

  18. Dear Sir,
    I had unprotected vaginal sex with a woman. Later on I found out she had HIV. I had a combo test (4th gen) done exactly 28 days after exposure. It was negative. I´m thinking about having another one done after 45 days. Which are the chances my previous test is a false negative?

    Thank you

    • I believe your test is conclusive and there is no reason for a false negative. But if you are concerned and are getting tested anyway, no harm in that.

      • I had a new 4th generation test done today (45 weeks after exposure and after my first negative at day 28) and still waiting for my results. The thing is I´m terrified with the idea of a false positive with this new test, now I was begining to get confident I had left all this behind. Besides I felt a little sick in the stomach these days and I´m afraid having some kind of stomach virus might give place to a false positive. Is that possible?

        I have another question. In the country where I live (Spain) the advised window period for a 4th G combo test is 45 days. Why is that so? Are low-quality tests used here or are the autherities being over-conservative?

        Thanks in advance.

        • Well, I got the result from my last 4th generation test (done 45 days after exposure). It´s a negative again.

          Is this deffinitive? Does it mean I can forget about it and go on with my life?

          Thanks in advance

  19. I had 9 weeks hiv 4th generation combo test negative and hep c.ab to ,pcr,rna qn test non reactive. Both non reactive. Is I m ok. I happnes year ago.

  20. Hello , i take a 5th generation hiv test after 45 day , IT vas negative , IT is safe ?

  21. Hi Doctor

    Had anal sex (i am bottom) and condom broke and just realize half way.
    Second day got fever and muscle ache.
    Can do test directly? Got chance positive?

    • There is risk of HIV transmission from this exposure. The window period for testing is 28 days for conclusive results. The earliest we can detect is 14 days with a 4th gen test, or 10 days with HIV RNA PCR. If your exposure is within 72 hours please visit us to discuss post-exposure prophylaxis (PEP).

  22. Hello Dr Tan,
    Two weeks before I went for massage with a thai lady she proposes me to do sex but I refuse it then we both removed our dress and she do massage for me after that I hug her and lick her nipples during the licking of her nipples my penis got rubbed on her thighs now am afraiding if there is some menstrual blood on her thighs and it got contact with my penile head means is there any chance of hiv please doctor please advise me I need to do any hiv test

  23. If both partner A is 100% confirmed negative initially, both partners tested for HIV Elisa 3rd Generation with negative result before exposure. Three months after exposure partner A and B both test negative for 4th generation roche cobas HIV combi PT, does this exclude HIV infection for partner A. Partner A is having swollen lymphnode in neck for 1.5 months. A is male and B is female

  24. John worried

    Hello doctor sorry but again

    Had a sexual encounter with condom (not sure if it was all the way on) 2 to 3 days later started feeling intense muscle aches , and flu like symptoms. Week 2 through 6
    All the other hiv symptoms occurred (no lymph nodes).

    Tested with 4 G duo antibody at 3, 4, 5, and 6 weeks all came back negative.

    Still experiencing loss of appetite and muscle aches @
    Week 7

    Should I still be worried and does ?

    Does 6 weeks count as conclusive in America ?

    Is it possible for symptoms to keep showing after 6 weeks?

    • Your tests are conclusive. If your symptoms were due to HIV, the tests would come back positive (even if you were in the window period) as ARS is caused by antigen+antibody response in the body. Stop being paranoid and move on with your life.

  25. John worried

    Hello doctor

    Had a sexual encounter with condom (not sure if it was all the way on) 2 to 3 days later started feeling intense muscle aches , and flu like symptoms. Week 2 through 6
    All the other hiv symptoms occurred (no lymph nodes).

    Tested with 4 G duo antibody at 3, 4, 5, and 6 weeks all came back negative.

    Still experiencing loss of appetite and muscle aches @
    Week 7

    Should I still be worried and does ?

    Does 6 weeks count as conclusive in America ?

    Is it possible for symptoms to keep showing after 6 weeks?

    • You conclusively do NOT have HIV. Please see a doctor to evaluate other possible causes for your symptoms and stop worrying about HIV.

  26. Hi doctor. I had protected sex with a sex worker, no ejacuation and condom did not break. I started PEP the day after exposure, now at day 13.

    Is there any test that I can do from day 14 onwards that would be rather conclusive? As from the picture of window period above, P24 is detectable from day 14.

    And if the sex worker goes for HIV test and shows negative, is there any chance that I will get HIV? Since there is also a window period for the sex worker.

    Thank you.

    • Your initial risk would be very low. But there is no test at day 14 which is conclusive in this situation, especially with PEP on board. If she is negative, you are at even lower risk, but not zero (as there is still a window period as you rightly said).

  27. Hello doctor,i went for lapdance to a strip club 5 week ago.next day i had loose stool..so i got worried of hiv..i went for hiv rna in labcorp which was negative and alere determine combo negative at 28 and 35th day..should i stop testing.

  28. Hello, doctor/ I’m from Russia.
    I had a dangerous situation unprotected sexual intercourse with an African-American women (the condom broke).
    In my country, doctors recommend to do a hiv test after 3, 6, 12 month after contact. And it is enshrined in law.
    I took a combo test (hiv 1/2) many times through 3, 4, 6, 8, 10, 12, 14, 16 weeks. Test system: hiv ag/ab cjmbo abbott architect.
    I also handed RNA (hiv 1/2) with a sensitvity of 20 copies 1, 2, 3 month.
    All the tests are negative.

    Of the symptoms i had – a reactivation of mononucleosis, but it was all over. And got chicken pox (first time). Slightly enlarget lymph nodes, jumps temperature (36,6 – 37,2), coating on the tongue.

    If I calm down and stop to pass the tests, it seems to me that the standarts in my country are outdated?
    Has your practice, cases of late seroconversion more than 3 month?

    Thank you very much fore the help.

  29. Hi Doctor, I did 4th generation combo test at 8 weeks as it was non-reactive, I wonder if I can consider this as conclusive? and if I need to re-test at 12 weeks? Thanks!