Absolutely not, especially as information changes. Is it so hard to understand that new information should change the message? That varying the message could reach people the old message did not?

Their job is not to be decisive, it is to inform, and an incomplete message repeated is inferior to an explanation including what is not known for certain, and just how uncertain it is and why.

Many, many opportunities for the CDC to educate have been squandered on preaching to the choir.

Edit: Though maybe you omitted a necessary "/s" sarcasm tag in favor of scare quotes.