New data from the Centers for Disease Control and Prevention shows the stunning spread of Omicron through New England as it overtook Delta as the dominant COVID-19 strain in less than a month.

The CDC’s Nowcast model, updated weekly, estimates the proportions of circulating variants both regionally and nationally.

Here, week by week, are the percentage of New England cases attributed to Omicron. The remainder each week are predominantly Delta.

  • Nov. 28-Dec. 4: 0.3 percent.
  • Dec. 5-Dec. 11: 1.5 percent.
  • Dec. 12-Dec 18: 19.1 percent.
  • Dec. 19-Dec. 25: 53.8 percent.
  • Dec. 26-Jan. 1: 84.2 percent.
  • Jan. 2-Jan 8: 96.4 percent.

“Omicron is more contagious and less lethal (than Delta),” says Dr. Ulysses Wu, Hartford HealthCare’s System Director of Infection Disease and Chief Epidemiologist, “but it is not more contagious and not lethal. It still does remain lethal. If you are, for the most part, healthy, vaccinated and boosted, you should probably be OK. But there are a significant number of people out there with comorbidities.”

COVID-19 Variant Proportions: CDC’s Nowcast Model

To view the proportion of COVID-19 variants, select the region from the dropdown menu under “HHS Region” (New England is Region 1). Then select a specific week for a breakdown of variants in the region. (Omicron is shaded purple.)

For a national overview, select USA under HHS Region and use the map below.


COVID in Connecticut: Town-by-Town Cases

Hover, or click, over any town to find the case rate per 100,000 population. (Updated each Thursday.)