The shape of the omicron wave is becoming clearer

The omicron variant has helped drive the United States into uncharted territory for the pandemic. The country was reporting an average of more than 400,000 new Covid-19 cases every day as of January 3, easily eclipsing last winter’s record of 250,000. And infections are still spiking, with the number of newly reported cases quadrupling since the beginning of December.

There is still a lot of uncertainty with the omicron variant: We’re still learning exactly how transmissible it is, how likely it is to cause severe disease and for whom. But we know more now than we...