Washington health officials are working with the Centers for Disease Control and Prevention and other national organizations to conduct a pilot study on surveillance of breakthrough COVID-19 cases.

The state will now use immunization records and match them to positive COVID-19 cases in order to identify breakthrough cases.

Previously, the state was relying on local health disease investigators to find out whether or not a person was two weeks past their second dose to verify that they had an actual breakthrough case.

Now the state’s pairing immunization records systems with positive COVID-19 case data to do that work instead.

As a result of the new surveillance system and the delta surge, the number of breakthrough cases reported this week has increased. There have been 21,757 breakthrough cases confirmed in Washington from Jan. 17 to Aug. 21 of this year.

“Our breakthrough cases still remain in the area we expect them, around 1% or less of all the vaccinated folks have breakthrough,” Dr. Scott Lindquist, acting chief science officer at the Department of Health, told reporters Thursday.

The delta variant makes up 98% of the most recently sequenced positive samples, and the increase in cases due to delta variant has led to an increase in cases, including breakthrough cases.

So far, 86% of people who test positive for COVID-19 despite being vaccinated do get symptoms of the virus, although the majority of them are not hospitalized.

Statewide, 80% of breakthrough cases are in people under the age of 64.

Just 9% of breakthrough cases confirmed in Washington have required hospitalization, and 185 people who were vaccinated have died from the virus. Many of these people had underlying health conditions that made them more susceptible to the virus, and health officials have stressed the risk of breakthrough cases are not a reason to not get vaccinated.

In fact, 94% of people hospitalized for COVID-19 from Feb. 1 to Aug. 9 were not vaccinated, according to state data.

Here’s a look at local numbersThe Spokane Regional Health District reported 424 new COVID-19 cases and no additional deaths on Friday. The daily numbers were the fourth time since the start of August that the district has reported more than 400 new cases.

There are 214 people hospitalized with the virus in Spokane hospitals.

The Panhandle Health District reported 112 people hospitalized with COVID-19 and no additional deaths.