Most Positive Coronavirus Tests Are True Positives

Why it’s nonsense to say that 90% of COVID-19 tests are false positives

Gideon M-K; Health Nerd
6 min readSep 21, 2020


Pictured: Science! Source: Pexels

In all of the times that we thought about a pandemic, in some hazy future that would probably never happen, the one thing that we mostly never foresaw was the truly epic amount of nonsense that would be produced. It seems like every second minute that a new myth about COVID-19 springs up that needs to be debunked, whether it’s the idea that drinking hot water can kill the virus (remember that from way back in April?) to the newer absurdity spreading around that most coronavirus deaths were actually caused by buses (spoiler: they weren’t).

Pictured: At least 50% bigger than your average virus. Source: Pexels

And so, when the newest misconception sprang up, instead of feeling elated that my purpose as a science communicator and blogger was being fulfilled, I instead felt the bone-crushing weariness that comes from total nonsense going very every single day of the year. And because this nonsense is about a pandemic disease, and policy makers do sometimes base their decisions on trash analyses published online, I felt like it’s important to address this inaccuracy as soon as possible.

Which brings us here, to the claim: that 90% of all positive COVID-19 tests are false positives. This has serious implications, the story goes, because it means that there are actually virtually no cases of the disease in the country, and the government is lying to us all*.

Which is, to be blunt, totally wrong.

“I dropped a steaming pile of that idea on the paddock just this afternoon” Source: Pexels

Let me explain.

Testing For COVID-19

The main test used to determine if someone has been infected with SARS-CoV-2, the virus that causes COVID-19, is called a polymerase chain reaction test or a PCR. PCR testing basically takes tiny amounts of viral DNA or RNA and amplifies it until you can detect it easily in a sample, and is one of the main ways we test for specific infections.