An emergency can happen at any moment, and the United States must be ready to respond to pandemics, natural disasters, and other public health threats. The Public Health Preparedness and Response: National Snapshot 2017 demonstrates how federal investments enhance the United States ability to respond to public health threats and emergencies.
https://www.cdc.gov/phpr/whyitmatters/00_docs/2017_PublicHealthPreparednessSnapshot_508.pdf