The highly contagious delta variant now accounts for 95 percent of all COVID-19 cases in Washington, but the variant’s footprint in Clark County is less clear.
The lack of detailed local information, which has led to many inquiries with Clark County Public Health, stems from how data on variants is collected and analyzed.
COVID-19 tests administered at doctors’ offices or at testing sites can detect the presence of SARS-CoV-2, the virus that causes COVID-19, but it doesn’t indicate what version of the virus it has detected, according to an explanation of the testing protocol shared on social media by Public Health.
“That’s why your provider may say they can’t test for variants,” the Public Health post said.
Identifying a variant requires a process known as genomic sequencing, which examines the genetic code of the virus from a sample and looks for mutations specific to one of many variants that have developed since the pandemic began.
The Public Health post said the process is involved and cannot be performed on every test administered in the state. Instead, health officials run sequencing tests on a representative sample of confirmed cases from around the state.
The state also sequences specimens in large outbreaks, in vaccine breakthrough cases and in cases with unexpected outcomes, such as if a young, otherwise healthy person is hospitalized with COVID-19.
“Sequencing in these situations may help to identify new variants that could be more transmissible or cause more severe illness,” the Public Health post said.
The result of that process creates a picture of the prevalence of different virus variants throughout the state, as opposed to reporting on a county-by-county basis.
However, a weekly report from the Washington Department of Health does track variants detected on a county-by-county basis since the beginning of the pandemic.
As of July 31, the delta variant showed up in 25 of the samples submitted in Clark County. The largest number of delta-positive samples was reported in King County, with 1,654, followed by Benton County with 371.
The delta variant accounted for 95.1 percent of all cases between July 18 and July 31, up from 89.4 percent of all cases sampled between July 11 and July 24, and 73.6 percent the previous week. Between May 30 and June 12, delta accounted for only 18.8 percent of all sampled cases, according to the Department of Health.