More contagious and aggressive coronavirus variants first identified in California and Brazil are increasing their numbers in Washington, according to a report published Thursday by the state Department of Health.
"Previously, it appeared the B.1.1.7, or United Kingdom variant, was going to be the predominant variant soon in Washington," said Dr. Scott Lindquist, the acting state health officer.
Now, the California variant, designated B.1.429, could become the most common strain of SARS-CoV-2 — the novel coronavirus that causes COVID-19 — in Washington.
The next few weeks will be telling, Lindquist told reporters in a weekly COVID-19 briefing.
In addition, a Brazilian variant, called P.1, has increased its numbers although it's far less prevalent. Brazil has now surpassed the U.S. for daily COVID-19 cases and deaths, largely driven by the P.1 mutation.
DOH is monitoring eight variants, collectively called "variants of concern." It tracks the prevalence of mutations through genetic sampling of a small percentage of specimens gathered from across the state.
On March 25, the cumulative total for the California strain was 345. On March 31, it was 745.
On March 25, the cumulative total for the Brazilian strain was two. On March 31, it was 13.
The California variant could be responsible for Washington's rising case rate, said DOH Secretary Dr. Umair Shah.
"We do think that is a part of it," Shah said. "We don't how much a part of it."
Compared with the initial strain of SARS-CoV-2, the California variant may be more infectious and cause more severe presentations of COVID-19, researchers say.
After King County, Yakima County had the highest numbers of the California strain. Pierce had the third highest. King accounted for nearly all of the Brazilian strain numbers.
Shah said the majority of infections can still be attributed to behaviors associated with exposure to the virus. He urged the public to wear masks and to follow social distancing and other guidelines.