La Plata County has marked its first official case of the omicron variant.

San Juan Basin Public Health confirmed the case on Tuesday after genetic sequencing identified the new variant of concern. Public health officials are now raising concern that the omicron variant is already circulating widely in Southwest Colorado.

A nearly two-week lag around the holidays meant variant sequencing detected the first omicron case on Tuesday from a positive test collected at a community testing site on Dec. 17.

An adult resident of La Plata County was the first to test positive for omicron in SJBPH’s jurisdiction of La Plata and Archuleta counties, said Chandler Griffin, a spokesman for SJBPH.

No other information about the person was available.

“In the last SJBPH interview with the case, they reported having mild to moderate symptoms, and the individual was at their home and not hospitalized,” Griffin said.

Public health officials expect omicron to drive up case rates in the coming days.

“We are anticipating and actually already seeing the emergence of a surge in cases of COVID-19,” he said.

“We expect that it’s an omicron-fueled surge, based on other surveillance, but the genomic sequencing is behind so we are dealing with incomplete information at this time,” said Liane Jollon, executive director of SJBPH.

On Tuesday, SJBPH’s team of contact tracers was working more than 140 positive cases that had emerged in the last 24 hours.

La Plata County averaged about 22 new cases per day last week, according to SJBPH data, though that number was skewed slightly lower by the holiday week.

“We suspect (the increase in cases) is a combination of holiday gathering and omicron spread across the country and this will be confirmed in the next few weeks as more sequencing comes back,” Jollon said.

“We believe there is community transmission of the omicron variant in our jurisdiction,” Griffin said.

The first confirmed omicron case in La Plata County is significant, but Jollon said it is relatively inconsequential given the about two-week backlog in genetic sequencing and the likelihood that omicron has been circulating in Southwest Colorado for some time.

“Having our first confirmed case is probably not nearly as important as the intensity of the surge that we are seeing in other locations in the country and now seeing in Colorado,” she said.

Colorado has had a marked rise in COVID-19 cases as omicron has started spreading across the state.

The Colorado Department of Public Health and Environment reported 5,549 cases on Dec. 23, nearing the record of 6,945 cases set on Nov. 12, 2020, during Colorado’s greatest surge.

The U.S. set a record for new cases during the pandemic on Wednesday with a seven-day average of more than 280,000, according to NPR. The previous high was set in January 2020.

As caseloads have soared, omicron has quickly become the dominant variant in Colorado.

The newest variant of concern accounted for just 1.33% of cases the first week of December and 27.55% of cases the next week, according to CDPHE data.

The most recent data for the week of Dec. 19 shows omicron accounts for more than 91% of all new cases in Colorado.

“If you look at the Centers for Disease Control and Prevention, they have changed their estimations of omicron prevalence over the last couple days,” Griffin said. “That part of the picture is going to become much clearer as we catch up with the sequencing results that we’re receiving daily.”

According to a SJBPH news release, fatalities from COVID-19 in recent weeks have been comparable to those during the previous height of the pandemic.

New research about omicron released in recent weeks has begun to offer more evidence of omicron’s transmissibility, severity and the efficacy of vaccines.

Researchers and public health officials have increasingly come to the conclusion that omicron is more transmissible than delta and other variants.

Scientists at the University of Hong Kong found that omicron multiplies about 70 times faster in the respiratory system than delta, reaching higher levels of infection in tissue within 48 hours.

Another study by researchers at the Ragon Institute of Massachusetts General Hospital, MIT and Harvard found that omicron was two times more infectious than delta.

There’s also emerging evidence that omicron will be less severe than delta, Jollon said.

“The question becomes how much less severe because if there are extraordinarily high numbers of positive cases, even if it’s less severe, (omicron) still has tremendous potential to overrun the health care system,” she said.

The CDC updated its isolation and quarantine policies on Monday based on new scientific evidence that indicates the first five days of infection are most critical for stopping the spread and extraordinarily high transmission that has once again disrupted the U.S.’s health care system and the economy.

Data from South Africa and the UK has shown that vaccines are less protective against infection from omicron, but boosters increase their efficacy and vaccines still ward off severe disease and hospitalization, according to the CDC and the UK Health Security Agency.

Two doses of an mRNA vaccine (Pfizer or Moderna) is about 35% effective against the omicron variant, according to the CDC. A booster dose restores protection against infection to 75%.

Two studies released on Thursday showed that Johnson & Johnson’s booster is also effective at preventing severe disease and hospitalization.

The unvaccinated account for 80% to 100% of those hospitalized for COVID-19 in Southwest Colorado, Griffin said.

“We expect that there will be people who are fully vaccinated and fully vaccinated and boosted who will test positive, but (they) are much, much less likely to experience severe infection, hospitalization or death due to omicron,” Jollon said. “And we expect that these positive cases who were fully vaccinated and boosted will be less likely and have a shorter time period where they may pass it on to others.”

With the rapid spread, Griffin and Jollon said residents of La Plata and Archuleta counties should act to protect themselves.

Full vaccination with a booster is the best way to guard against COVID-19, Griffin said.

Residents of Southwest Colorado should also wear well-fitting masks in public that fit snugly over the nose and mouth without any air leaks, avoid large gatherings, continue to social distance and minimize interactions outside of their household, Griffin said.

“The time to take precautions against omicron is now. It was yesterday,” Griffin said. “Don’t wait for us to say omicron now makes up the majority of cases.”

ahannon@durangoherald.com