Covid-19 blood test for antibodies - all about the blood test. Is it reliable? Are there different types and are some better than others? What about its reliability and its accuracy? Are there false postivies or false negatives?

What about pricing? Are there different prices for the test? Is there any price gouging or profiteering going on?

This test is suppossed to show if you have had the covid-19 virus in the past, and if your body has developed antibodies in response to it.