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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.

Click here to learn about the Different Generations of ELISA

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.

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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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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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  1. Dear Dr Tan…

    This was our previous conversation…..

    November 10, 2014

    I met a girl, a student and we started dating, we had sex, several times for several weeks and i performed oral sex on her too…On all but one occasion occasions i used a condom and used it well…on this single occasion the condom broke and i pulled out immediately cos i was on top, then replaced it and continued…on another occasion, she had traveled for two weeks and i missed her, so i masturbated and had some abrasion on around the base of my penis…then the next day she came back and we had protected sex…Tragedy struck when she got ill and i helped her get to the hospital, during her treatment, a test was performed on her and was found HIV positive..when she got well i asked her why she didnt tell me of her condition, she only said she would have but i was always using protection…we broke up hence forth…its been two years since then but am still scared she might have infected me…i havnt had any test yet..what are my odds…

    November 12, 2014

    Wow. I am so sorry to hear that. The good thing is your chances of getting HIV from this is still rather low. I would ballpark your risk at about 1 in 1000 at worst. You really should get tested. Be brave, it is very likely that you will be OK.

    I am thrilled and couldnt wait to share with you that i finally took the Almighty All Fearing HIV Test…It was the Antibody Test After over two Years of exposure…it came Negetive…Hope is conclusive…I also had to post it here so that others that may be facing similar situation as mine may know…As for the oral Thrush, i think its GONE or going, cos it dosnt burn like before, just litle tingles or maybe its just in my head…ALthough few days ago i examined my tongue after scraping and brushing, i noticed some red tiny pin-point dots or rather bumps like about five of them around the center of my tongue, which when i scratched them hard with my nail, they bled. and was litle painful for a day…also noticed that my palate and mouth roof was a little yellowish instead of pink…i still feel ok though but plan to go to the hospital on my next leave from work…hope is not something to be worried about. thanks again…

  2. Aleere determine combo test conclusive at 94days? I has exposure wit a gal wit an unknown status.94days ago. I had bloodless cut on ma pennis. Protected tho but d condom busted and I withdrew immediately. After 94days I did aleere determine combo test/fourth generation. Is it conclusive?

  3. I slept with HIV pos woman vaginal on 1 june, I did a SD Bioline at 28 June came Neg. I did SD Bioline combo at 3 october came Neg again, is this conclussive? Am frastrated I have dizzyness, feel light, weak, chest turns yelloy, burning sensations on my arms, memory loss, aches, joint pain, runny nose, flaky skin, gum bleeds thou it from my child hood, green viens on my arms, but no headache. But it all went away after 5 months

    • In my opinion your tests are conclusive. There must be some other explanation for your symptoms.

  4. Dear doc…thanks for the good work you do here, you dont know how much sickness you have cured by just answering these questions..Please gimme a reply soon…I had an exposure to a Hiv positive lady two years back unknowingly, we had sex and had orals sex on several occasions but we used protection…on one of the occasions the condom broke but i withdrew immediately, i didnt get tested cos i was scared, but when i asked around, it was like my chances are very low…now i recently developed what i will call oral thrush, although i try to backdate the time i started having the symptoms to when i had oral sex with a lady whom i beleive had verginal yeast which she may not know cos she complained of painful sex but has no discharge…i started tasting salty and sugary taste in my mouth alternating from time to time…then a burning mouth sensation, i am still scared to go to hospital for the fear of the hiv exposure… my tongue looked like it had white covering over it although a dentist said it looked normal, but i am still having the burning mouth sensation, i convinced myself it was thrush and started treating it with fluconazole 100mg 2 times daily, it almost cleared but at the end of 15days treatment, the burning came back after a week, i got a Nystatin Suspension annd took 4 drops four times daily,i have finished the second bottle of Nystatin, and the burning sensations feels like its cumming back again two days after nystatin, i just started using warm salt water solution to rinse my mouth every morning and evening, yet no much improvement, i am scared this is one of the signs of Hiv manifestation, i have no other symptoms, no fever, sour throat, ulcers or swolen lymphnodes, am just fine just that sometimes i feel dizzy and weak which i atribute to the drugs i was taking….please i need your advice..IS THIS A SURE HIV MANIFESTATION…I am trying to make up my mind to get tested but am scared of disapointing my fiancee whom am getting married to by end of this year,,she loves and believes in me so much and i can afford to disapoint her..Not in this way…HELP!!!!

    • There is no such thing as a “sure HIV manifestation”. Oral thrush can be caused by a HIV infection. Oral thrush can also be caused by many other diseases. There is no point pondering. You must test. I think by not testing you are being even more unfair to your fiancee.

  5. Hi dr. Had protected sex (not sure about the condom being broken) and having swollen lymph nodes in neck and groin. 5 week EIA test was negative. 10 week oraquick oral swab test also negative. Is this accurate and conclusive?

    • Very accurate but only considered officially conclusive at 3 months post exposure.

  6. I had exposure 3 months ago I did rapid finger pick test at 8 weeks and 12 both non reactive double eia confirmatory test at 13 weeks it also came negative is it conclusive?

  7. doc ive been throug oral sex in september 22,2014 and the i get tested on nov. 12,2014 they used SD bioline hiv ag/ad combo the result is nonreactive. but im still nervous does my result accurate? and does the time require is relevent when i get tested?

    • The combo test is conclusive after 28 days. I see no reason for you to doubt the test.

      • Doc, i had an hiv duo combo in a lab at 7 weeks it came out negative after having sex with a condom, expire one) but did not break.. can i trust the results.

        i am confuse because it says that p24 drop down after a month, please help me out.

        • Yes the P24 can be down but then the antibody will already be detectable. In my opinion it is conclusive.

  8. I had massage in thia. She kiss me and give me hand job . Is it possible to be infected ? I am very worry can’t eat can’t sleep

  9. Hey Mr tan I had unprotected sex in March 3 2014 I went to my doctor September 5 2014 he did a finger prick test that take about 10 to 20 to get back your result it was negative How accurate is that test sir plz help.

    • I do not know what test your doctor did. But generally a HIV test at 6 months post exposure is accurate.


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