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Coloradans who have been vaccinated against coronavirus are more than 90% less likely to develop COVID-19

Of the 106,965 positive cases for COVID-19 since Jan. 21 in Colorado, 819 of them occurred in people who were fully immunized

Dr. Steve Groshong, left, administers the Pfizer-BioNTech COVID-19 vaccine to Woody Laughlin during a drive-through vaccine clinic in the parking lot at National Jewish Health on Jan. 29, 2021, in Denver, Colorado. (Kathryn Scott, Special to The Colorado Sun)
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Coloradans who have been fully vaccinated against the coronavirus are more than 90% less likely to develop COVID-19 and vastly less likely to be hospitalized, state health officials said on Tuesday.

The numbers provide local confirmation of data seen in the vaccines’ clinical trials and also support officials’ oft-repeated statements that the vaccines will end the coronavirus crisis.


“Vaccination is going to be our ticket out of this pandemic,” Dr. Rachel Herlihy, the state’s top epidemiologist, said.

Through Monday, 1,489,481 people in Colorado were reported to be fully immunized against the coronavirus. Of the 106,965 positive cases for COVID-19 since Jan. 21 in Colorado, 819 of them occurred in people who were fully immunized.

The Colorado Department of Public Health and Environment conducted two analyses to estimate the vaccines’ efficacy.


The latest from the coronavirus outbreak in Colorado:

  • MAP: Cases and deaths in Colorado.
  • TESTINGHere’s where to find a community testing site. The state is now encouraging anyone with symptoms to get tested.
  • VACCINE HOTLINE: Get up-to-date information.


In the first, the agency looked at case rates during the week of April 4. Vaccinated people were 94.6% less likely to be a reported case during that week.

In the second analysis, the agency examined two-week incidence rates among the unvaccinated, partially vaccinated and fully vaccinated populations. Herlihy said the analysis showed full vaccination corresponds to about 93% protection against becoming a reported COVID-19 case. Partial vaccination — have only the first shot of a two-shot series, for instance — corresponds to about 66% protection, according to the analysis.

“A very small percentage of the cases in the state are occurring among fully vaccinated individuals,” Herlihy said. “This is very consistent with the studies that were seeing nationally.”

It’s also highly unlikely that fully vaccinated Coloradans who catch COVID-19 will be hospitalized because of the disease. Colorado has seen an increase in people hospitalized with the disease in recent weeks. But fully vaccinated people make up a tiny fraction of those hospitalized. On a typical day, Colorado might see 40 or 50 people hospitalized with COVID-19, but at most only one of those would be someone who is fully vaccinated.

“The vaccine is working exactly as it is supposed to in Colorado,” Gov. Jared Polis said.

Colorado remains in the throes of the pandemic as more transmissible coronavirus variants drive an increase in cases across the state. There are more people hospitalized because of COVID-19 in Colorado now than there have been since January.

Polis encouraged all Coloradans to get vaccinated — even those who have held off because they thought finding an appointment was too difficult or because they didn’t want to take a spot from someone more at risk from the virus.

“For those of you who have been putting it off, now is the time to get it,” Polis said. “Maybe you’ve thought: ‘Hey, I’m 24. I’m healthy. I want to let my elders get it.’ Well, guess what? Now it’s your turn.”

The state is opening up three of its mass vaccination sites to walk-in appointments. 

“It’s easier than ever before and we want to get that message out,” Polis said.

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