PCR tests for COVID-19 utilize 1980s technology involving purification of viral RNA, conversion to DNA via reverse transcriptase, and amplification using primers and DNA polymerase.

“First: how #Covid_19 PCR tests work. It’s 1980s tech, a kid could run one, but if you don’t care, skip down to the flaws... 1. Get a nose or lung mucus/cell sample, deeper the better. 2. Purify the viral RNA and turn it to DNA using reverse transcriptase (RT), hence it’s name, the “RT-PCR” test. 3. Add in two types of short pieces of DNA called “primers” that stick to precise places on the viral genome. Because DNA is a 2 stranded zipper (with strands running in reverse directions), the primers are made to bind to opposite strands, and point towards each other. Tidbit 1: the CDC screwed up the design of the DNA primers. Bad design leads to them sticking to other places in the human genome or failing to bind efficiently to the virus. Tidbit 2: Primers are cheap these days. You can buy a quintillion of them for $1. That’s the number of different ways a Rubik’s cube can be arranged. 4. The tiny reaction also has a heat-stable DNA polymerase, which acts like that little handle on a zipper, but it’s special. It grabs onto the primer and, while it’s closing it, makes a whole new side of the zipper. https://t.co/wHNLmoQ33o 5. After a few minutes, the DNA zippers are heated to 203F to separate the DNA zipper stands. 🧬 When the reaction cools, the process is repeated, amplifying the DNA exponentially. After 30 cycles you have about a billion copies of each viral genome.”