Answer by Josiah Tay:
There are over 30 types of STDs (or STIs) to be sure, ranging from the well known ones like HIV, chlamydia to less well known ones like Mycoplasma Genitalium. The common tests you see in the market today, or even the tests in the common hospitals and clinics today, cannot possibly cover all of them. Also, no test on earth is 100% accurate, but probably something like 99.87%. Herpes tests in particular are very inaccurate, sometimes as low as 60%. Hence there is the possibility of a false negative test result, ie that you are carrying some virus or bacteria, but your test result is negative because of certain reasons e.g. the amount of virus/bacteria in your body is not at high enough levels to trigger a positive result.
So the solution? Test again a 2nd time or 3rd time. Which specific disease are you worried about? For each disease, the window period and test accuracy varies. Consult your doctor about this instead of asking on the internet, because your doctor had to go through many years to get his licence, whereas anybody on the internet could answer you, even a teenage kid who just happened to read an article on STDs on the net and “feels like” answering you. (not me by the way, haha)
Some STDs do not have tests for them, e.g. for HPV in men, there are no tests in the market that can test for HPV in men (though you can probably arrange a lab to do an individualized experiment on you). Yet, HPV is one of the most common STDs in the world – about 80 million people in USA have HPV. (see figure)
You also mentioned STD symptoms, but actually you shouldn’t be worried about symptoms, because some of the most common and most serious STDs don’t even have very obvious or long lasting symptoms, such as chlamydia and HIV. More than 50% of men with chlamydia do not have any symptoms at all.
Some STDs like some strains of Herpes are actually quite harmless most of the time and you shouldn’t be too worried if you have it. There are 2 strains of Herpes – HSV-1 (Oral Herpes) and HSV-2 (Genital Herpes). You can see the prevalence of HSV-2 on the above figure. HSV-2 causes sores to appear on your genitals, but HSV-1 causes sores mostly restricted to your oral area.
Guess what? HSV-1 is so common that over 60% of the world population has it. But most of the time it just results in sores in the mouth, so no worries even if you have it. Although some people don’t consider Oral Herpes as an STD, but it can be transmitted by sex and it can in some cases cause sores in the genitals too, so I would think of it as an STD too.
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