It may be a result of people letting their guard down and not taking the advise of experts in the field with contagious deceases and viruses, such as social distancing and mask wearing.
The top administration and assistants to Trump may have thought their inner social circle was clean and protected, they now know that was not true..
The only way to protect an active social environment is to test people creating a guarded bubble and keep them there as it were or to test them everyday with quick results before interaction with one another..