Short answer: they have all been bottlenecks thus far. In fact, that's a big reason why testing hasn't improved as rapidly as everyone hoped it would. The bigge

Short answer: they have all been bottlenecks thus far. In fact, that's a big reason why testing hasn't improved as rapidly as everyone hoped it would. The biggest bottleneck now is dwindling supplies of personal protective equipment (PPE) for those involved in obtaining and handling the test specimens.