You seem to conflate antibody testing with viral rna testing. The former is somewhat difficult because you can't make the reagents necessary overnight, and the

You seem to conflate antibody testing with viral rna testing. The former is somewhat difficult because you can't make the reagents necessary overnight, and the reagents are unique for the virus. Essentially, you have to clone the gene for an immunogenic portion of the virus (the spike protein most likely), express it in a recombinant host (which may require extensive optimization), purify it, and then validate that it properly detects blood of people who were confirmed positive for viral RNA and then recovered. That all takes time, and then you have to scale up manufacturing. In contrast, the the viral rna (RT_PCR) test takes about a day to design and the reagents are synthesized overnight and then you can run the test in the morning of the second day. Scaling that up to 1 million viral RNA tests a day should add at most a month, but our country already runs this number of tests a day if you count every academic, research, hospital, and CLIA lab, so the manufacturing capacity already exists.