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Coronavirus

Colorado’s omicron-driven COVID spike has reached record heights. Here’s how to make sense of it.

More people now have the virus -- and are potentially capable of spreading it -- than at any other time during the pandemic

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Colorado’s omicron variant-driven surge in coronavirus infections is obliterating daily records in the state, leading to the most dizzying spike of the pandemic.

At the same time, hospitalizations during the spike are rising slower — though still at a worrying rate.

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The result is a fast-changing situation that is challenging some of the state’s foremost experts at tracking the pandemic and predicting where it will go next.

“It’s extremely challenging to model what is happening and will happen with omicron,” said Elizabeth Carlton, a professor at the Colorado School of Public Health who is a member of the state’s COVID-19 Modeling Group.

Here’s what you need to know to understand where we stand as we near the start of (sigh) the third year of the pandemic.

Omicron has exploded like nothing we’ve seen before

On Dec. 16 — that’s less than three weeks ago — Colorado was seeing an average of 1,635 new coronavirus infections per day over the previous week. On Sunday, the state hit a weekly average of 7,282 new infections per day. That’s a record for the pandemic.

A chart by the Colorado Department of Public Health and Environment shows the rolling average of the number of new COVID-19 cases reported in the state per day. The data are current as of Jan. 3, 2022. (Provided by CDPHE)

Colorado has also during this surge recorded its highest-ever number of new infections on a single day: 11,018 reported on New Year’s Eve. That’s more than 4,000 more infections than the non-omicron record, when 6,945 were reported on Nov. 12, 2020.

This means there are now more people infected with the virus and more people potentially capable of spreading the virus than at any other time during the pandemic.

“There is a very strong probability that people you encounter in the days ahead are potentially infected,” Carlton said.

It’s not just the heights that make this spike so dramatic. The omicron wave reached those numbers in a little over two weeks.

During the state’s previous record COVID wave — in fall and winter of 2020 — it took nearly 2½ months from when cases started rising until when they peaked. During this year’s delta-variant-driven wave — previously the state’s second-biggest surge — it took more than four months from when cases started rising to when they peaked.

The surge isn’t confined to just a few counties anymore

In its early stages, the omicron surge looked a lot like the coronavirus’ initial arrival in Colorado: It took root in ski counties.

Those counties are still getting pounded with new infections. On Monday, Summit County was tied for the nation’s top hotspot in the New York Times’s COVID tracker, with 525 new infections per day per 100,000 population.

A map from the Colorado Department of Public Health and Environment shows the cumulative incident rate of new COVID-19 infections over the previous week in Colorado counties as of Jan. 3, 2022. Counties in red have the highest incidence rates. (Screenshot by John Ingold, The Colorado Sun)

But, again like the virus’ first wave, the omicron wave has now spread to far more counties. On Monday, 28 Colorado counties reported one-week cumulative incidence rates that would have placed them under a stay-at-home order during the state’s earliest dial system.

Hospitalizations are rising, too, but more slowly

On Monday, 1,167 people were in Colorado hospitals with coronavirus.

That number is a worrying jump from just a few days ago, but the spike in hospitalization is so far rising only about half as quickly.

In the first week after reports of new infections began rising, cases increased by about 88% — from a daily average of 1,635 on Dec. 16 to 3,071 on Dec. 23.

But in the first week after new coronavirus hospitalizations began rising, the numbers grew by only 44%. On Dec. 21, Colorado saw an average of 108 new coronavirus-related hospital admissions per day over the prior week. On Dec. 28, that figure had risen to 156. On Monday, the number stood at 202.

A chart by the Colorado Department of Public Health and Environment shows the number of new COVID-19 hospital admissions per day. The red line shows the seven-day rolling average of new admissions. The data are current as of Jan. 3 2022. (Provided by CDPHE)

Carlton said this is potentially a good sign. But there are important caveats. Even if hospitalizations rise more slowly, the sheer volume of infections could send enough people to hospitals to overwhelm capacity. And, omicron is still very dangerous for people who are unvaccinated, while those who are fully vaccinated and boosted are best protected.

“In general, we’re seeing less risk of hospitalization with omicron, but this remains a severe disease among the unvaccinated,” Carlton said.

Of additional concern, the health care system is less equipped to deal with the omicron wave than previous waves. The state’s hospital intensive care units are still about 93% full. Among patients in the ICU in Colorado, about 30% are there because of coronavirus, according to federal figures. Meanwhile, half of Colorado’s hospitals report that they expect to experience a staffing shortage in the coming week, further straining their ability to care for patients.

Some traditional virus-tracking numbers may not be as reliable

On Sunday, the weekly average of coronavirus tests across the state coming back positive hit an all-time high: 23.99%

Throughout the pandemic, that kind of number has been a sign that Colorado is not catching nearly enough infections or doing nearly enough testing. The oft-stated standard for the positivity percentage is 5% — low enough to ensure that you are catching most of the cases and have enough testing available.

A chart by the Colorado Department of Public Health and Environment shows the number of PCR coronavirus tests performed per day. The red line shows the rolling average of the percentage of tests that came back positive over the previous week. The data are current as of Jan. 3, 2022. (Provided by CDPHE)

But fewer people are also getting tested now than during the 2020 COVID surge. One possible reason is the proliferation of at-home rapid tests, which people may be using as a first line of defense before going to seek a more-reliable PCR test. If that’s happening, then you would expect the percentage of positive tests being reported to the state to go up — because people who are negative may be choosing not to go get tested, tilting the sample pool toward those who are infected.

Carlton said it’s not clear to what extent that’s happening in Colorado, but she doesn’t think it’s enough to negate the worrying positivity numbers.

“The spike in positivity over the last two weeks — at-home testing alone cannot be driving that spike,” she said.

Omicron has basically kicked delta out

For months, the delta variant was basically the only form of the coronavirus circulating in Colorado. The state’s surveillance system for detecting variants went 13 straight weeks without picking up signals from any variant other than delta.

A chart from the Colorado Department of Public Health and Environment shows the proportion different variant strains make up in regular surveillance sequencing. Delta, in light purple, had long dominated transmission in the state, until omicron, in teal, rapidly took over. (Provided by CDPHE)

But now, in the span of a month, omicron has come to dominate the scene. The variant made up an estimated 91% of new infections in Colorado for the week of Dec. 19, and Gov. Jared Polis said last week that he wouldn’t be surprised if the percentage now is above 95%.

“If you get COVID, there’s a very high chance that it’s the omicron variant right now in Colorado and around the world,” Polis said.

More booster shots may be on the way

Some of the earliest people in Colorado to get a booster dose of coronavirus vaccine are closing in on the six-month mark from that shot. Time for another immune system pick-me-up?

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A campaign in Israel — an early adopter of booster shots — is doing just that. The country is offering a fourth dose of the Pfizer vaccine to anyone 60 and older who is at least four months out from their third dose.

Data from that effort will likely inform decisions in the U.S. about whether to approve additional boosters here.

So, is the end of the pandemic near? Tread lightly.

Omicron’s tremendous transmissibility has caused some experts to speculate that this could be the pandemic’s “exit wave.” If a milder form of the virus spreads broadly, seeding widespread natural immunity to go with what the vaccines can offer, then maybe this will be the variant that ultimately pushes COVID to the background of our lives.

“It does each time feel like, ‘How could it get worse?’” Carlton said.

But she is more cautious than others. The coronavirus has thrown so many curveballs throughout the pandemic that predicting its next trick with any certainty is near-impossible.

“If anyone tells you that they know what is coming after omicron, question their credibility,” she said.