What would happen if an even more serious pandemic broke out?

Look,I'm not saying that the pandemic of 2020 wasn't a serious matter.Many people got sick;many died.But in retrospect,it's clear that at least some of the dangers and responses to the situation were exaggerated for political purposes.What if a new man made disease broke out across the world,one that was actually %99 communicable in everyone,no matter what their age.What if it were established that it would cause %40 of the population to be hospitalized and be fatal to around %15, again irregardless of age or gender.How would the United States handle such an event?What would be the official protocols?How would society continue to function?Only serious,detailed answers please.