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HIV – Understanding the Window Period

 

 

 

 

Asian Geographic article on HIV

Asian Geographic article on HIV

The HIV window period often 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 ELISA which 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.

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 NOT have 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 Tests, Western Blot, RNA PCR, DNA PCR and 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?’

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.

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 MUST get 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

HIV Signs and Symptoms

The HIV Window Period and Test Accuracy

HIV PEP Post Exposure Prophylaxis

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3,622 Comments

  1. 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.

  2. 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.

  3. 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.

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

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

  6. 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 ……….

  7. 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?

  8. 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?

  9. 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?

  10. 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?

  11. 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?

  12. 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

  13. 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.

  14. 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

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