Yes, viral mutations tend to make a bug more contagious, but they also tend to make it less deadly because it’s contra-survival for a virus to kill its host. That’s why today’s flu viruses are far less of an issue than their ancestor of 1918, which took tens of millions of lives over two years, as we noted Thursday.

People in the Pentagon worry about global thermonuclear war, but they don’t highlight those concerns to the public because it’s an extreme possibility. Her message should have centered overwhelmingly on her reassuring words on Delta: “These vaccines operate really well in protecting us from severe disease and death.”

Then there’s the CDC’s foolish about-face on masking for the vaccinated: Even if it were better-qualified, the message all too many Americans get is the agency’s advisories are arbitrary and senseless — or, worse, that it has lost confidence in the vaccines to protect us right now.