The Colorado Department of Public Health and Environment on Wednesday rolled out its first data on breakthrough cases of COVID-19, those which affect vaccinated populations. 

According to state epidemiologist Dr. Rachel Herlihy, the current wave of the pandemic is unique in that it is having more of an impact on pediatric and school-age children. Case data as of Aug. 22 showed the highest current rate of transmission is among 6-11-year-olds, who are too young to be vaccinated. The next highest is among the 12-17 year old population, she said.

Another worrying trend: the steady increase in hospitalizations, at 891 as of Wednesday. Herlihy explained that hospitalization data lags by about two weeks, in order to obtain the most complete picture possible. The number of patients hospitalization with COVID-19 is the highest since January, she said.

While breakthrough cases are on the rise, most of the hospitalizations are among the unvaccinated population, Herlihy said. 

CDPHE data shows the older population are the most susceptible to breakthrough cases, she said, which she attributed to a less-than-robust response to the vaccine. However, the risk of COVID is still about 3.4 times higher for unvaccinated people than for those who have taken the vaccine. The risk of hospitalizations for COVID-19 are 3.7 times higher for unvaccinated, and the risk of death is 5.8 times higher for the unvaccinated. 

Among the vaccinated population, the most cases by percentage have been reported for the 30-39 age group, at 20.8% of all breakthrough cases, although they represent just 16.6% of all vaccinated individuals. Another 17.1% of cases are showing up among the 40-49 age group, and 15.1% of cases among the 20-29 age group. All of those percentages exceed the total vaccination rates of those populations, according to CDPHE data.

CDPHE data said newly reported cases are at 1,593 per day, based on a seven-day average. That’s also the highest case count reported since May and more than five times the number of cases reported in June, which was the low watermark this year.

Herlihy also showed the pediatric vaccination rate by region, which showed the central mountain, Foothills and Mile-High regions with the highest vaccination rates for 12-17-year-olds. About 56% of that age group have received at least one dose of the COVID-19 vaccine. 

By race and/or ethnicity, white non-Hispanic populations are now seeing the most breakthrough cases, at 74.8% of the total number of cases, with Hispanic cases at 13.3%. 

Herlihy also noted the Delta variant is raising the risk for breakthrough cases.