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AURORA, Colo. (KDVR) — Some Colorado counties are making moves to reinstate mask recommendations amid rising COVID-19 rates and questions about the dangers of the delta variant.

Multiple Colorado counties made moves Thursday to fall in line with the new guidelines from the Centers for Disease Control and Prevention, which recommend all people wear masks indoors, regardless of vaccination status. Local health experts say this regression in the pandemic could have been avoided if more people got the COVID-19 vaccine.

“The challenge now is the unvaccinated have become a petri dish, and the virus is mutating and changing within this population of the unvaccinated,” said Dr. Richard Zane, chief innovation officer with UCHealth.

Unvaccinated make up ‘overwhelming majority’ of severe cases

New data indicates even vaccinated people can transmit the delta variant to those who either can’t or won’t get vaccinated. There’s also concern about high-risk individuals contracting the virus, even if they’re vaccinated.

“If you’re vaccinated and you’re healthy, you don’t need to worry. The overwhelming majority of people who are getting sick — sick enough to get admitted to the hospital or dying — are unvaccinated people,” Zane said.

Zane said they are not seeing breakthrough cases lead to serious illness or hospitalization at this time.

“The longer this variant persists, the more exposure vaccinated folks will have, and we’ll start to see some of the people who are most susceptible break through and get cases of the virus,” said Dr. James Neid, director infection prevention with Medical Center of Aurora.

The less vaccinations, the more dangerous variants

Neid said he believes broader measures are necessary right now to remind people the pandemic is not over, and that means masks in certain areas.

“A highly vaccinated area where there are very few cases, I don’t think mask mandates are as important,” Neid said.

Neid said his main concern is bringing kids back to school in the fall, as young age groups are still not eligible to receive the COVID shot.

“It becomes increasingly concerning that we could propel this pandemic and go back to major problems,” Neid said.

Masks are only a way to slow the spread of the virus. Health experts agree the vaccine is still the primary weapon to protect the population and end the pandemic.

If vaccination rates don’t increase, it will likely lead to more variants that could potentially be more contagious.