The antibody humans produce to fight off the S Spike protein is the CR3022 protein. All human affecting corona viruses, known as sarbecoviruses, have an S Spike protein. Even the coronavirus strains that cause the common cold trigger your immune system to create cr3022 protein on the polyprotein chains in your white blood cells. This means the antibody tests are unreliable because they show positive for every sarbecovirus. PCR tests aren't much better because of the similarity in the genetics of sarbecoviruses. Even the packaging and instructions clearly state that contraindications can occur from other strains. This is why there are so many cases and no deaths. Anyone can go to the BLAST database and see that, despite claims of millions of cases, only a few thousand SARS COV 2 examples have been sequenced and they are so similar to SARS COV that many are debating if they can be considered two different strains. In fact, up until the end of March, they were using SARS COV tests to test for SARS COV 2.