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DENVER (KDVR) — COVID-19 hospitalizations are increasing across Colorado, with some hospitals seeing their highest numbers since last winter.

According to state data, Colorado had 665 confirmed COVID-19 hospitalizations on Monday — the highest number since mid-May. A majority of hospitalized patients are unvaccinated. Recent data shows that unvaccinated people accounted for 83.3% of hospitalizations in a single week in August.

Dr. Ivor Douglas, director of the intensive care unit at Denver Health, says attention should be paid to how successful Colorado has been in keeping COVID-19 numbers down compared to other states.

“This is not Alabama, this is not Texas and not Florida. But we are in trouble,” Douglas said.

Doctors report ‘dramatic’ patient declines

Denver Health is among the hospitals seeing an increase in COVID-19 patients.

On July 31, Denver Health had six COVID-19 patients and one in the ICU. On Monday, the hospital reported 16 COVID patients: eight in the ICU and six on ventilators. Of the total COVID patients, all but two were unvaccinated.

Douglas said based on his own anecdotal experience, some COVID-19 patients appear to be declining quicker with the delta variant compared to previous strains of the virus.

UCHealth is also noticing an increase in COVID patients, with 202 as of Monday and 80 in the ICU.

“We’re seeing some of our patients — not all of them … come in and then almost like an airplane crash and burn. It is literally that dramatic in terms of decline,” Douglas said.

‘Vastly’ underestimated how many people would not get vaccinated

Dr. Richard Zane, UCHealth’s chief innovation officer, said the rise is due in part to the raging delta variant, waning vaccine immunity and not enough people getting the COVID shot.

“We have waning immunity in the setting of a huge number of unvaccinated people. We’ve vastly, unfortunately, underestimated how many people would not get vaccinated,” Zane said.

Current COVID-19 numbers only tell part of the story, according to Douglas. He said there are key differences in how they treat patients now — compared to the start of the pandemic — that ultimately help keep people out of the ICU.

“We have learned so much and we are learning so much. The ability for us to provide multidisciplinary care at the bedside has significantly improved,” Douglas said.

Health experts continue to push the vaccine as the best protection against the virus. About 66% of all eligible Coloradans are fully vaccinated.