Despite Delta, Breakthrough Cases Remain Rare In Washington

SEATTLE — The rapidly-spreading delta variant is causing a nearly-unprecedented wave of new COVID-19 cases across Washington. Despite that, and despite the fact that delta causes a higher viral load in vaccinated patients who catch the disease, the Washington State Department of Health says breakthrough cases remain rare in the Evergreen State.

According to the latest data from the state, between January 17 and August 21, 2021 Washington saw a total 21,757 vaccine breakthrough cases — cases where patients who have been fully vaccinated, but still caught COVID-19. To put that in perspective, Washington has 4.1 million vaccinated people, so just 0.5 percent of vaccinated Washingtonians suffered breakthrough cases. Those cases are unfortunate, but unavoidable, the DOH said.

"[B]reakthrough cases should be expected. That’s because none of the COVID-19 vaccines are 100% effective at preventing infection," the agency said. "There are differing reasons why, but it’s largely because viruses evolve over time and undergo changes as they spread and replicate. This is also common for non-COVID vaccines, and it’s why we need flu shots every year."

CDC studies found that more than 99.99 percent of people who were fully vaccinated against COVID-19 did not die or require hospitalization. That's been largely true in Washington as well: of those 21,757 vaccine breakthrough cases, just 9 percent of patients required hospitalization and less than 1 percent died of COVID-19 or COVID-related illnesses.

The DOH says that's good news, because there had been concerns that the delta strain might overpower vaccines and result in more breakthrough cases. Previous variants produced smaller viral loads in fully vaccinated people than in unvaccinated people, but the delta variant appears to produce the same high viral load in both the vaccinated and unvaccinated alike.

As of the Department of Health's latest analysis Thursday, the delta variant accounts for 98 percent of all recent COVID-19 cases in Washington state. To protect against the delta variant and the current, fifth wave of COVID-19 infections, the DOH continues to urge anyone who is on the fence about vaccination to consider taking the shot, resume masking in public, practice physical distancing and frequently wash hands.