A recent article in the Daily Mail carries this very long headline, “Why ARE COVID cases plummeting? New infections have fallen by 45 percent in the U.S. and 30 percent globally in the past three weeks but experts say the vaccine is NOT the main driver because only eight percent of Americans and 13 percent of people worldwide have received their first dose. ”

The story goes on to recount the opinions of various experts as to why cases are dropping. It finally comes to the conclusion that the drop is likely due to a higher number of people who’ve had the virus than official counts suggest and that as many as 90 million people in the U.S. may have already been infected.

But these experts may have missed an important factor that led to this decrease: the test that is used to diagnose the presence of COVID-19 in patients has been changed recently to make it less sensitive.

A Polymerase Chain Reaction or PCR test detects genetic material from the COVID-19 virus. It can find the presence of a virus if you are infected at the time of the test. The PCR test can also detect fragments of the virus even after you are no longer infected. The test swabs are placed into a machine called a thermocycler which uses temperature to denature or separate the DNA of the virus and then replicate it using an enzyme

To amplify a segment of DNA using PCR, the sample is first heated so the DNA denatures, or separates into two pieces of single-stranded DNA. Next, an enzyme called “taq polymerase” synthesizes — builds — two new strands of DNA, using the original strands as templates. This process results in the duplication of the original DNA, with each of the new molecules containing one old and one new strand of DNA. Then each of these strands can be used to create two new copies, and so on, and so forth.

The cycle of denaturing and synthesizing new DNA is repeated as many as 40 times, leading to more than one billion exact copies of the original DNA segment. If you have a full-blown symptomatic case of COVID-19, the thermocycler will pretty quickly detect it among all the other DNA in the test sample because symptomatic cases contain higher viral loads. The fewer cycles it takes to find it, the higher the viral load you have in your system. And that is the problem.

The makers of the thermocycler typically set the machine between 40-45 cycles by default. It is up to the users in the lab to lower it to a cycle threshold (Ct) that gives more accurate results. But a thermocycler set at the factory at 40 cycles is going to keep running the test until it is not finding the active and replicating live virus but the debris that remains of it AFTER you’ve recovered from exposure and can’t pass it on to anyone.

Imagine a large bowl of multi-colored M&Ms candies, with red M&Ms representing a piece of COVID-19 DNA. Each cycle is akin to taking a scoop from the bowl. If the bowl had a large percentage of red M&Ms, the likelihood of the first few scoops (or cycles) to include one or more red M&Ms would be higher, and therefore indicative of an active infection. If the bowl had a very small number of red M&Ms, it would take more scoops (cycles) to retrieve a red one. The higher the number of scoops, the higher the likelihood that you’d retrieve a red candy at some point.