I have read somewhere that CDC was trying to make a 3-in-1 test kit for SARS, MERS and this new SARS-Cov-2 virus but it was giving bad accuracy and false positives, and now they are making the one for the sars-cov-2 only.
They were making a 3 in 1 kit, but that's because the 1 was an internal control and the other 2 were two different places in the viral genome in case one mutated and became silent.
