u.s., which would be standard practice if we were asked. obviously, we would have responded. >> was it a mistake not to use those tests. >> it was a mistake not to use everything that we had and every tool. >> confident in their own abilities, the cdc chose to develop and distribute its own test, a decision that would come to haunt the agency and its director. >> early coronavirus test kits may have been contaminated, leading to a possible delay in the cdc's ability to get those kits to health labs. >> within about five weeks, with the fda's agreement, we got all of the public health labs of this nation to have an effective test. >> so that would have been five weeks. >> probably about five weeks it took to correct it. >> five weeks, which many have called the lost month. when covid-19 spread across the united states, mostly undetected.