As Colorado slogs by its fourth winter of the COVID-19 pandemic, a curious pattern has emerged.
This season — at the least to date — the state reached its peak for hospitalizations of individuals with COVID within the second-to-last week of November. That’s virtually precisely when a peak occurred final 12 months. And the 12 months earlier than that. And the 12 months earlier than that.
4 years, 4 completely different predominant variants of the virus, 4 completely different ranges of vaccination and immunity within the inhabitants. And 4 instances that COVID hospitalizations started rising in late summer season or early fall and, extra notably, started to say no in Colorado proper round Thanksgiving.
“Fascinating and beguiling,” is how Elizabeth Carlton, a professor of epidemiology on the Colorado College of Public Well being, described the phenomenon.
“I feel, by now, there in all probability is one thing taking place driving this sample,” she stated — as an alternative of the pattern being a statistical fluke.
What that one thing is, although, nobody is aware of.
“It’s an fascinating sample,” stated Dr. Rachel Herlihy, the state epidemiologist on the Colorado Division of Public Well being and Atmosphere. “I don’t assume we will absolutely clarify it.”
What’s taking place with COVID now
Because it looks like everybody you understand is sniffling or coughing or in any other case testing optimistic for one thing, here’s what we find out about Colorado’s present COVID traits:
- The late-November peak got here with 280 folks within the hospital with COVID.
- As of final week, there have been 246 folks within the hospital with COVID. (Carlton stated hospitalizations have turn into the important thing metric to look at for COVID traits as a result of they inform you how a lot severe sickness there may be; knowledge on infections has turn into much less dependable as extra folks take a look at at residence and don’t report the outcomes.)
- After declining by December, hospitalizations started rising once more after the brand new 12 months, doubtless prompted partially by the arrival of a brand new variant, dubbed JN.1. The variant is sweeping throughout the nation, pushing infections larger nationally. Herlihy stated the variant seems to be extra transmissible and higher at escaping prior immunity than others.
- It’s unclear if infections are persevering with to extend in Colorado, although. Up till final week, numerous measures used to foretell the virus’ unfold — issues like what share of checks on the state’s community of “sentinel” labs are coming again optimistic and what number of emergency room visits resulted in a COVID analysis — had been trending larger. Each of these backed off barely final week.
- One measure used to trace how widespread infections are — how a lot of the virus may be detected in wastewater — continues to indicate excessive ranges. However each Carlton and Herlihy stated it’s doable it is because JN.1 could also be higher at infecting cells within the intestine, which means it’s shed extra incessantly in poop, skewing the evaluation.
- The scenario stays rather more managed than any earlier 12 months of the pandemic. Final 12 months’s peak for hospitalizations was 440. The years earlier than that noticed peaks of greater than 1,600 folks within the hospital at one time.
Carlton stated it’s necessary to keep in mind that even when COVID ranges are falling or aren’t as extreme as in prior years, we’re nonetheless in the course of the excessive season for all types of respiratory diseases — comparable to flu, RSV and that bizarre hacky-cough virus going round this 12 months that nobody can fairly appear to establish.
Which means folks ought to proceed to take precautions, comparable to staying residence in the event that they’re not feeling properly, searching for remedy when sick and contemplating sporting a masks in crowded locations. It’s additionally not too late to get vaccinated with an annual flu shot, an up to date COVID booster or, if eligible, an RSV vaccine.
Colorado’s perplexing peak
Colorado’s late-November COVID peaks are uncommon as a result of they have an inclination to occur sooner than peaks throughout the remainder of the nation. Final 12 months, hospitalizations peaked nationally in January, similar because the 12 months earlier than.
They’ve additionally typically had the impact of blunting the arrival of a brand new variant. When a brand new variant referred to as XBB.1.5 swept throughout the nation final 12 months, it had little impression in Colorado, maybe as a result of our earlier-breaking wave had constructed up a layer of contemporary immunity within the state.
This isn’t at all times the case. In early 2022, Colorado noticed a major rebound in infections and hospitalizations in January, pushed by the arrival of the unique omicron variant. This 12 months’s traits might show to be a smaller-scale model of that.
However the November peak has remained a COVID fixed in Colorado, sticking to a a lot tighter turnaround schedule than different respiratory viruses just like the flu, which typically hits early and typically later in winter. It is usually intriguing as a result of, with vacation journey in late November and December, one would usually anticipate to see instances growing because of this.
Carlton stated she’s thought of some theories which may assist clarify the peaks. One chance is climate patterns — viral transmission adjustments as temperature and particularly humidity ranges do, with drier air extra favorable to an infection.
“We’re only a drier state and we all know this virus appears to unfold below dry situations,” she stated.
The college calendar might have an effect. Colorado’s faculty 12 months tends to begin sooner than in another states. Mobility and journey habits can also play a task — say, extra folks heading to the mountains to go snowboarding or spending extra time indoors.
However none of those fairly matches both, she stated. Some falls have been wetter than others over the previous 4 years. And, to ensure that hospitalizations from COVID to begin falling in late November, infections would wish to start slowing at the least a pair weeks prior, earlier than ski season and college breaks actually begin.
4 winters in and there may be nonetheless a lot left to find out about this virus.
“I feel what COVID has taught us is that it evolves extremely quickly,” Carlton stated. “So what we expect we all know at the moment might change by tomorrow.”
