Who's most at risk in Colorado for COVID-19 breakthrough cases

The number of positive COVID-19 cases among vaccinated people continues to hit new highs in Colorado, driven by the proliferation of the Delta variant.

Threat level: The risk varies depending on age and the type of vaccine received, Colorado public health officials said Wednesday.

• The vaccinated population between ages 30 and 39 is disproportionately represented among breakthrough cases, followed by the 40–49 and 20–29 age groups.
• Those who received the Johnson & Johnson vaccine also account for a larger number of the breakthrough cases compared with Pfizer and Moderna.

Why it matters: The insights are evident in data posted publicly by the Colorado Department of Public Health and Environment for the first time Wednesday.

• The figures are the most comprehensive look at COVID breakthrough cases among vaccinated people across the state, and the publication comes after weeks of questions.

The big picture: Unvaccinated people in Colorado continue to drive the pandemic, state public health officials say.

• A vaccinated person is 3.4 times less likely to contract the coronavirus and 5.8 times less likely to die from the disease.
• The latest numbers only go through the week of Aug. 22 because officials say a delay is necessary to verify the data.

Details: The reasons that certain populations are more at risk remain unclear. "We have those same questions you have," state epidemiologist Rachel Herlihy told Axios Denver.

The fact that young people make up a larger proportion of the breakthrough cases is likely the result of exposure, whether as workers in the service industry, or because they’re traditionally more risk tolerant and spend more time socializing, Herlihy said.

• These age groups also possibly received more J&J vaccines, which are less effective than the others available.

The bottom line: The latest data, Herlihy says, provides "clear information about the different level of risk of becoming a COVID-19 case, of being hospitalized or dying of COVID-19 … if you are unvaccinated versus vaccinated."