MEDIUM TO HIGH

COVID cases resurgent in all counties in the state

All eight Connecticut counties are now listed as areas of medium or high COVID transmission, according to the U.S. Centers for Disease Control and Prevention.

Launched in February, the CDC’s communitylevel, color-coded map organizes transmission into three categories: low, medium and high.

The CDC map shaded all of Connecticut as either orange or red, signifying either medium or high levels of transmission.

“This latest CDC update is a reminder that Connecticut is in the midst of a swell from a subvariant of omicron,” state Department of Public Health Commissioner Manisha Juthani said.

New Haven, Hartford and Middlesex counties are listed as “high” transmission. Fairfield, Litchfield, New London, Tolland and Windham are listed as “medium” transmission.

The CDC said it examines the combination of three metrics — new COVID hospital admissions per 100,000 people, the percent of staffed inpatient beds occupied by COVID patients and the total new infections per 100,000 people in the past seven days — to determine the community transmission level.

"This approach focuses on preventing hospitals and health care systems from being overwhelmed and directing prevention efforts toward protecting people at high risk for severe illness,” the state

DPH said in a statement.

Yale researcher Nathan Grubaugh said there are several sublineages of omicron that are factors to the surge. BA.2, which caused what Juthani referred to as the latest COVID “swell,” is comprising 73 percent of all samples he's tested as of Thursday.

Another subvariant, known as BA.2.12.1, comprises 23 percent of all samples, with the parent, omicron, the remaining 4 percent.

BA.2.12.1 has two distinct mutations, Grubaugh said, causing “some additional immune escape with this variant.”

That means a higher likelihood of reinfection and breakthrough cases.

“Some of your neutralizing antibodies from past infections or from the vaccine would be less effective,” Grubaugh said. “It doesn't obliterate your neutralizing antibodies, but it does reduce those.”

Grubaugh said the subvariants are also not following the same patterns as previous COVID strains. Tests for COVID in wastewater, which had been a reliable metric for anticipating the spread of the coronavirus, are no longer matching what he's seeing and hearing in the community.

“The anecdotes around this are quite disturbing,” Grubaugh said. “It seems like a lot of people that I know over the past four weeks have had COVID.”

Across the state, COVID cases are rising, though new hospitalizations have not kept pace. The state said Friday there were 239 patients in Connecticut hospitals fighting a COVID infection, an increase of 27 over the past seven days.

In the past seven days, there have been 6,297 new COVID cases discovered out of 56,223 reported tests for a positivity rate of 11.2 percent.

Omicron and its subvariants are less virulent than previous COVID strains, but the current slow rate of hospitalizations may pick up over time.

“All of that could be because there's a delay in the dynamics of hospitalizations,” Grubaugh said. “There are still hospitalizations. It's just not at the same levels that it has been in the past.”

Grubaugh explained that viral transmissibility is a function of three things.

The first is “viremia,” which is the variant's ability to replicate, if one variant tends to produce more virus than another.

That is what Grubaugh called “brute force mechanisms,” and it's what made alpha spread more than the original coronavirus, and delta more than alpha. Omicron didn't replicate quite as much as its predecessors.

But transmissibility is also a question of where a virus likes to take up residence.

Older coronavirus strains prefer to bind with cells in the lower respiratory tract, which tends to make infections worse, but doesn't spread as easily.

Omicron, however, likes cells in the upper respiratory tract. Infections are not as bad, but it's easier to spread.

“It would be very difficult for those lower respiratory variants to out-compete omicron,” Grubaugh said.

But now BA.2 and BA.2.12.1 have both the upper respiratory advantage and, simultaneously, are replicating better than omicron (BA.1).

“When we look at the amount of virus in people, we see an increase,” Grubaugh said. “BA.2 produces more.”

Erik Trautmann / Hearst Connecticut Media As Connecticut’s seven-day COVID positivity rate has surged past 10 percent, the CDC has classified all of the state’s counties as having medium or high transmission.