Such （public health emergency）declarations can pertain to the entire country or to a specific state.
Public health emergency declarations ease certain laws and regulations to make it easier to address the emergency and allow some federal grant money to flow toward addressing the emergency.
A public health emergency is a lesser event than a national emergency, which triggers a rapid outlay of federal money to address the emergency. National emergencies also give great power to the president, allowing the president to do things such as activate the National Guard.
https://www.pennlive.com/nation-world/2017/10/public_health_and_national_eme.html
