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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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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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3,405 Comments

  1. Jenna Loster

    Hi Dr Tan, between 2008 and 2011 I was very promiscuous. After all those encounters a year later i took an oraquick test in 2022 and it was negative. Between 2012 and upto now I had three new partners. I randomly developed Gingivitis in what i believe is to be trench mouth in June. I wasnt aware I had dental issues till June and i got diagnosed with gingivitis. Around november i felt awful extremely fatigued and dry eyes mouth and diarrhea for a few days along with headaches i felt like this for a few weeks. I still have earaches clogged ears and little to no sense of smell. My last exposure was the end of July and I took two oraquick tests using saliva. I took one December 8th and Dec 15th they both came out negative. Could I trust this test? or could the test from 2 years ago could be wrong and i could have late stage hiv so i could not be producing antibodies anymore?

    • I assume you mean you took the OraQuick test in 2012. July to Dec is 5 months. Really the OraQuick test is as good as conclusive. If you want to get into the nitty gritty, the OraQuick test has been shown to have a negative predictive value as low as 98% in low prevalence settings. In all practical sense this should make no difference to you and I am sure you do not have HIV.

  2. Dear Dr Tan,

    I have done an HIV Antibody screening test under Pantai Premier Pathology 30 DAYS after exposure to an unprotected sex, which I dont know if she was hiv positive or not. It came out as non reactive. I dont know what testing method did they use. But I think it was EIA test. So my question is,

    1. Is the test result conclusive and reliable?
    2. What is the window period for the EIA test?
    3. Do I need to retest again after sometimes?

    Your reply is much apprciated Dr Tan.

    Best Regards.

    • 1. It depends on what method they used. If it is just an EIA then it is not conclusive. 2. 3 months. 3. Yes 3 months.

  3. Dear Dr Tan…

    This was our previous conversation…..

    chuks
    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…
    reply

    drtan
    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.

    NOW MY POST

    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 sometime 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, the gum of one of my upper canine seem to be eroded exposing a little more tooth, i suspect gingivitis.…i still feel ok though apart from these and a few joint pains which i attribute to a lack of exercise but plan to go to the hospital on my next leave from work…hope is not something to be worried about. thanks again…

    • Thank you for sharing. Is there something you want to ask me? I don’t see a question in there.

  4. Dr. Tan, I had recent unprotected sex with an HIV+ woman. On one occasion there was menstrual blood on my penis. I took the finger prick test 4 weeks after exposure. It came back negative. What are the chances that the test is a false – negative ?

    • It depends on which finger prick test you took. If it was the Combo test you can relax. If it was the antibody test you can also relax but you should get it done again at 3 months post exposure.

  5. Hello dr tan you are doing a wonderful job….I had unprotected vaginal exposure with known hiv positive prostitute in june..I am uncircumcised and during sex my penile foreskin started bleeding..one week after my exposure I got viral pharyngitis and fever both took 1week to subside..after 2 weeks I suddenly started getting joint and muscle pains..it started from my knees and now my whole body is affected..soles of my foot on both sides have become extreme red and are paining like hell..my both knees also are very painful..its been 5 months my joint and muscle pain aren’t going..they are becoming worse day by day..I haven’t slept from last 5 months because of severe pain..my esr and crp levels were highly elevated at 40 and 48..I met rheumatologist he told me I have got some kind of rheumatic disease..cause is unexplained..can be viral infection..I have taken almost all nsaids to injections to relieve my pain but its not going..I have taken 4th generation tests at week 6,9,12,15,and last 20 weeks after exposure it came out negative..in between I took hiv proviral dna test at 6 weeks and hiv quantitative rna pcr by cobas taqman at 3 months which detects less then 48 copies.this also came negative..I want honest advice from you is my testing upto 5 months enough or I have to take more testing following my rheumatic disease?I have seen in american college of rheumatology that most people with hiv infection have rheumatic diseases and appear as primary manifestation :(..m in horrible pain..I don’t wanna live in this pain :'(..m just 27 and only son of my parents..last year I had life threatening condition severe pancreatitis liver inflamed bile duct blocked..was hospitalised for 45 days..seeing my lifethreatening conditions in previous months and looking at my current rheumatic disease is my 5 month 4th gen test is conclusive?

    • Your tests are conclusive and you do not have HIV. You better get that Rheumatic problem sorted out man. These things can become very chronic and very crippling.

      • Thank you so much dr tan :)..god bless you..love you for your wonderful work..you are a great human being :)keep up with your wonderful work….I trust on u and will keep hiv out of my mind..just one more question I wanted to ask..as I m uncircumcised and blood exposure was there is there any chance I might be coinfected by hep c along with hiv?I have tested for hepatitis c also at 3 months and 5 months..as my rheumatic disease is worsening and related with both hiv and hcv..still my 5 months test for both are conclusive?thank u dr tan

        • Dr tan kindly reply to my last question….

          • Your Hep C test is conclusive. Relax. Anyway, if you are worried about Hep C extending the HIV window period, that does not seem to be an issue anymore.

      • Thank you for the answers dr tan god bless you:)..I am just worried about my rheumatic disease which is worsening day by day….I fear I won’t be that rare person who doesn’t turn out positive till a year or 2 because of my life threatening serious illness last year when I was admitted for 45 days.. :(..I will take your words and ll try to forget about hiv and hcv :)

      • Dr tan sorry to disturb u again….I went to 1 neurologist who told me that your symptoms fit well with cidp…chronic inflammatory demyeliniting polyneuropathy….I have seen in all medical journals and studies that cidp is the manifestation of hiv in most of the patients….:(everywhere cidp is linked with hiv..do u think my 5 month hiv testing is enough to rule out hiv or am the rare person who isn’t producing antibodies nor antigens and viral rna :(….

  6. Dear Dr. Tan…I I posted again on the outcome of the test i had the other day. the post is upto a week and you havnt replied yet…although you did reply others after it. please find time to reply, am waiting for your response. sorry about its lengthiness

    • Sorry. Can’t find it anymore. Too many comments. Can you repost your question? Thanks.

  7. Hi, i had unprotected sex in thailand with 3 girls. I also had 2 condoms broken by that time. This happend in the month september. I got tested at 22 september ab/ag because i had 2 days flu and had to go to tiolet. I could barely move. At 7 and 24 october i did an ab/ag test again and at 12 november again(45 days before my last risk). Are these results conclusive? Because i had a big risk and went ill in that period.

    Thank you doctor

  8. I had oral sex wit a lady both insertion nd receptive.i had bruise on my pennis bloodless cos it was bin treated den nd almost closed totally.she dint av any cut or sore in her mouth only pure saliva was on er mouth.after 5 weeks I went for hiv 1 nd 2, p24 combo test. (G.s bio-rad combo). Nd I took her for hiv 1 nd 2 antibody test (aleere determine) we r both negative. But am scared cos of d bloodless bruise on my pennis.Wats d possibility of hiv infection?

    • It does not matter. What matters is that your HIV test is already conclusive. So you do not have HIV.

  9. Dear Dr Tan…

    This was our previous conversation…..

    chuks
    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…
    reply

    drtan
    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…

  10. 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?

  11. 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.

  12. 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.

  13. 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.

  14. 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?

  15. 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.

  16. 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

  17. 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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