Why the Omicron offshoot BA.5 is a big deal

The culprit this time is yet another Omicron offshoot, BA.5. It has three key mutations in its spike protein that make it both better at infecting our cells and more adept at slipping past our immune defenses.

In just over two months, BA.5 outcompeted its predecessors to become the dominant cause of Covid-19 in the United States. Last week, this subvariant caused almost 2 out of every 3 new Covid-19 infections in this country, according to the latest data from the CDC...