That's an easy statement to make two years later. Now that we have the benefit of hindsight, we know a lot of things that would have helped.
When you make evidence-based decisions, you are going to get some things wrong. The only way around that is to gather more evidence, and that takes time (and loads of money.)
That begs the question as to whether an evidence-based approach is the right approach in all circumstances.
Another way around it is to not fully rely on an evidence-based approach, and take precautions before the evidence comes in. In some circumstances (e.g. rapid spread of an poorly understood disease) waiting for an evidence-based decision before taking precautions might be too slow.
The issue is that they really didn't know how rapidly it was spreading at the beginning.