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Delta coronavirus explodes across Colorado. That’s bad news for unvaccinated people.

This scanning electron microscope image shows particles of the virus SARS-CoV-2 (round magenta objects) emerging from the surface of cells cultured in the lab. SARS-CoV-2 is the scientific name of the virus that causes COVID-19. The virus shown was isolated from a patient in the United States. (Provided by the National Institute of Allergy and Infectious Diseases's Rocky Mountain Laboratories in Montana)
The state’s top epidemiologist says the variant is the most transmissible one Colorado has seen

Infections from a dangerous new coronavirus variant are surging across Colorado, causing health officials to amp up the urgency in their messages for people to get vaccinated.

The Delta variant, which is believed to have originated in India and is also known as the B.1.617.2 variant, was first identified in Colorado in late April. By the first week of this month — a period of about six weeks — it had grown to account for an estimated 40% of all new infections in Colorado.

For comparison, it took eight weeks for the Alpha variant — also known as the B.1.1.7 or United Kingdom variant — to reach 40% of the state’s total cases. As of early June, that variant made up an estimated 48% of total cases in Colorado, but its share is falling as Delta’s rises.

Nationwide, the Delta variant is believed to account for about 10% of new cases.

Dr. Rachel Herlihy, the state epidemiologist, said the Delta variant is believed to be about 50% more transmissible than the Alpha variant, which itself was 50% more transmissible than the original form of the virus.

“At this point, it is the most transmissible variant we’ve seen,” Herlihy said.

But, for most people who have been fully vaccinated, this news shouldn’t cause too much alarm. While the vaccines are believed to be slightly less effective against the Delta variant compared with other forms of the virus, they still offer strong protection.

A study in the United Kingdom, for instance, found that two doses of the Pfizer vaccine are 96% effective against the Delta variant at preventing severe COVID-19 requiring hospitalization.

For unvaccinated people, it’s a different story.

The high transmissibility of the variant means it is less likely people will be able to avoid the virus without protection from a vaccine, Herlihy said. The variant is just too good at jumping from vulnerable person to vulnerable person.

And that means, even as the state opens back up and life returns to its pre-pandemic norms, there is more danger now to people who aren’t vaccinated.

“I would say, at this point in the pandemic, the risk to unvaccinated individuals is greater than it was several months ago,” Herlihy said.

Read more at the Colorado Sun

The Colorado Sun is a reader-supported, nonpartisan news organization dedicated to covering Colorado issues. To learn more, go to coloradosun.com.