HIV RNA (RT-PCR) testing in Taichung: the window period explained
A condom breaks. Or sex happens with no protection at all. For most people the hardest part is not the result. It is the waiting, and the feeling that nothing can be confirmed yet.
Explained by Dr. Chao-An Chen, urologist, at 昭安泌尿科診所 (Morning Urology Clinic), West District, Taichung.
In short
- RT-PCR looks for the virus itself. It detects the RNA of HIV (human immunodeficiency virus) in the blood. RNA is the genetic material of the virus. The test does not wait for your body to produce antibodies.
- From about 10 to 33 days after exposure it can be used as an early reference point. Before about ten days, this kind of test has little reference value.
- If the exposure was less than 72 hours ago, medication comes first. Post-exposure prophylaxis (PEP) is the urgent step at that point, not a blood test.
- An early “not detected” result does not replace the later tests. Follow-up still has to be completed along the window period schedule. A standard antigen/antibody test at 12 weeks after exposure is what settles the question.
- Results are read together with your exposure history by a physician. Costs are explained at the consultation.
What the window period is
Standard HIV screening — an enzyme immunoassay (ELISA) in a laboratory, or a rapid test — mainly detects what your body makes in response to the virus: antibodies, and in some tests an antigen as well.
Every immune system reacts at its own speed. Antibodies usually take several weeks to several months to appear. The period in between is called the window period. During it an infection may already be present, but the test cannot show it yet. It is a limit of the test. It is not a judgement about you.
This is why reading about symptoms online late at night does not help. Symptoms are not a test result. A test taken too early is not a test result either. What decides the answer is the type of test, and the number of days since the exposure.
How RT-PCR is different
RT-PCR stands for reverse transcription polymerase chain reaction. It is a nucleic acid amplification test (NAAT, a PCR-type test). It is done on a blood sample.
It does not depend on the immune response. Instead it uses nucleic acid amplification to look directly for HIV viral RNA, the genetic material of the virus itself. Because it looks for the virus, and not for your reaction to the virus, an infection can be detected much earlier. That makes it a useful early indicator after a high-risk exposure.
| Antibody screening / rapid test | HIV RT-PCR (nucleic acid test) | |
|---|---|---|
| What is measured | Antibodies produced after infection, and in some tests an antigen | HIV viral RNA, the genetic material of the virus itself |
| Window period | Longer. It waits for the immune system to react, usually several weeks up to about 3 months | Does not wait for antibodies to form, so an assessment can be made earlier |
| When to test | From 1 month to 3 months or more after exposure | About 10 to 33 days after exposure, as an early reference |
| Role | The standard on which the final conclusion rests | Shortens the anxious waiting period considerably; an early reference, not the conclusion |
Put simply: an antibody test asks whether your body has noticed the virus. RT-PCR asks whether the virus is there. The two questions can be answered at different times. That is why they sit at different points on the timeline below.
The timeline after a high-risk exposure
- Within 72 hours — ask about PEP, not about testing. If the high-risk exposure was less than 72 hours ago, come to the clinic straight away for post-exposure prophylaxis (PEP). Medication is the direct way to interrupt infection at that stage. Contact us by LINE, or book an appointment, immediately.
- About 10 days — the earliest a nucleic acid test means anything. Before about ten days have passed, a nucleic acid test has little reference value. Testing earlier than that usually gives a result you cannot rely on.
- About 10 to 33 days — the RT-PCR window. In this period the test can serve as an early reference. RT-PCR also suits people who missed the 72-hour period for medication, and people who have finished a course of PEP and want early confirmation.
- 12 weeks — the test that confirms the final result. Even when RT-PCR shows “not detected” at an early stage, a standard antigen/antibody screening test at 12 weeks after exposure is still recommended.
Prevention with medication after an exposure is not limited to HIV. Depending on what happened, syphilis, chlamydia, gonorrhoea and trichomoniasis can also be considered for preventive treatment. Whether this is appropriate for you is assessed at the consultation.
Who this test suits
If you have had contact with body fluids and you cannot be sure it was safe, comparing symptoms on the internet will not settle it. A test will. RT-PCR is worth discussing if any of the following applies to you:
- After high-risk sex — contact with body fluids from a partner whose infection status you do not know.
- A broken condom, or sex without protection — the barrier failed, so the risk of exposure rose sharply.
- Needle exposure, or shared needles — an accidental injury from a needle of unknown origin, or sharing of needles.
- Possible acute symptoms, and you want an earlier answer — repeated fever, swollen lymph nodes or a sore throat in the days after an exposure. These symptoms resemble a cold, and the worry that comes with them is often high.
These are reasons to come and be assessed. On their own, they are not evidence of infection.
What an early result does and does not settle
- A “not detected” RT-PCR result is reassuring, but it does not replace the follow-up. The result still has to be assessed by a physician, and further tests arranged where needed. Follow-up has to be completed along the window period schedule before the final status is confirmed.
- Interpretation belongs with a physician. What a value means depends on your exposure history and your general condition, taken together. Health education material, including this page, cannot do that part for you.
- PEP and RT-PCR answer different questions. PEP is about preventing infection within 72 hours. RT-PCR is about detecting infection early. One is not a substitute for the other.
If you would like to see how HIV testing sits next to the timelines for syphilis, chlamydia and gonorrhoea, the timeline page after a risky encounter puts them all on one line.
If you are not a Taiwanese national
Two questions come up often. Both deserve a clear answer.
Residence. Since 4 February 2015, HIV infection on its own is no longer a reason to restrict the entry, residence or stay of a foreign national in Taiwan. One general rule still applies. Under Article 18, subparagraph 8 of the Immigration Act, entry may still be refused where a communicable disease is a danger to public health. If your own situation is complicated, please check it with the competent authority rather than rely on a web page.
Records and reporting. We are required by law to report certain infections to the health authority. Your personal information is protected by the Communicable Disease Control Act, Article 10.
Two practical points for the visit. Please bring your passport or resident certificate; it is needed to create the medical record. If you are not enrolled in Taiwan’s National Health Insurance, the consultation and tests are self-paid.
A separate service, for comparison. 昭安泌尿科診所 (Morning Urology Clinic) is also an anonymous screening facility commissioned by Taiwan CDC (institution code 3503241524). For this service we do not check your National Health Insurance card or any identity document, so it is open to you regardless of nationality. There is no charge for it. No formal report can be issued, because no identifying information is recorded. That programme covers HIV, and at this clinic it is a rapid blood test. It is a different test from the RT-PCR described on this page, and it has a different window period.
Your visit
- Book through the online form, through LINE, or by telephone. If the exposure was within 72 hours, please say so when you book.
- Registration. Bring your passport or resident certificate. Consulting rooms are separate, and patient flow is arranged so that you do not have to explain why you have come while you sit in the waiting area.
- Consultation. The date of the exposure, what happened, any symptoms and any earlier test results are reviewed together. That is what decides which test is useful today.
- Result and follow-up. The result is explained by a physician. The dates of any further tests are set at the same time, so you leave knowing what happens next.
Useful to bring: the date of the exposure, any earlier HIV or other test reports, and a note of any medication you are taking.
Frequently asked questions
The exposure was three days ago. Should I book a test?
If less than 72 hours have passed, the priority is an assessment for PEP, not a blood test. If more than 72 hours have passed, testing becomes the sensible route. Even then, a nucleic acid test needs about ten days after the exposure before it carries reference value.
My RT-PCR result was “not detected”. Is that the end of it?
It is a good sign, but it is not a substitute for the rest of the schedule. A standard antigen/antibody screening test at 12 weeks after the exposure is still recommended before the matter is treated as settled.
I have finished a course of PEP. Can I use RT-PCR?
Yes. RT-PCR is used both by people who missed the 72-hour period for medication, and by people who want early confirmation after a course of medication has ended. The timing is set at the consultation.
Does a negative HIV test cover the other infections?
No. An HIV test says nothing about syphilis, gonorrhoea, chlamydia or genital warts. Which of those to test for, and when, depends on the type of contact and on the window period of each infection. Genital warts are assessed separately, by the type of lesion, and are not included in general screening.
Can I read the report myself?
You will receive your result, but the interpretation is done with a physician. A number on its own does not tell you what it means. It has to be combined with your exposure history and your current condition.
Related pages
Appointments and access
Consultations are conducted in Mandarin, and can also be conducted in English.
昭安泌尿科診所 (Morning Urology Clinic)
No. 98, Boguan 2nd St., West District, Taichung City 403, Taiwan（403 臺中市西區博館二街98號）
Consulting hours: Monday to Saturday (closed Sunday). Online booking is open 24 hours.
This page was produced by 昭安泌尿科診所 (Morning Urology Clinic). Medical content last updated: July 2026 (same as the Traditional Chinese version). English version published: 4 September 2026. Medically reviewed by Dr. Chao-An Chen, urologist.
Sources: Taiwan Centers for Disease Control / Laws and Regulations Database of the Republic of China (Taiwan).
This page provides general medical information and does not replace an individual diagnosis or treatment plan. Please confirm anything concerning your own symptoms or test results at a face-to-face consultation.