Health research needs accurate data, and it's how we figure out which medications/procedures are better/worse/harmful. In normal circumstances, that research would protect the people involved
However, in some situations, that potential benefit isn't worth the potential harm from the data being abused. I can see why people would prefer to limit that data in the states, even if that is to the detriment of those seeking care
Based on the way the new CDC director responded, it sounds like she wants the data for harmful reasons, rather than helping improve care