The notion that the first recorded case of COVID-19 in the United States — a Snohomish County man diagnosed with the illness in mid-January — represents America’s Patient Zero for the novel coronavirus is “clearly false,” the county’s top public-health official said Friday.

“Maybe it was that individual that was the first introduction in January, (but) it certainly wasn’t the only one,” said Dr. Chris Spitters, health officer for the Snohomish Health District. “And it’s reasonable to assume, given reports like the ones that we’ve had and others around the country, that introduction may have occurred prior to January, as we initially suspected.”

Spitters’ remarks came during a morning telebriefing with reporters to provide a regular update on the district’s coronavirus case counts and give a new accounting of 35 “probable” cases that are based on positive serology tests of residents previously exposed to the virus.

Two of those positive antibody tests involved residents who told the district’s case investigators they got sick with COVID-like illnesses in December, several weeks prior to the nation’s first confirmed case on Jan. 20, raising questions about the arrival of the virus into Washington and the U.S.

More on the COVID-19 pandemic

While both cases are considered “probable,” from a public-health perspective, Spitters said respiratory-tract symptoms experienced in December in each case overlap with other illnesses. He added “it’s possible — and frankly, I think more likely” that each patient didn’t have COVID-19 then, but later picked up a mild or asymptomatic case of it, leading to the positive antibody test results.

“But we can’t say that with 100% certainty,” he said. “I think that’s just the more likely scenario.”


A definitive timeline of when COVID-19 was introduced into the U.S. remains in question, as scientists say the virus spread undetected before testing was widespread here.

Genetic sequencing has shown that a strain of the virus that traces back to the Snohomish County man diagnosed on Jan. 20 remains the dominant one in Washington and the Northwest, but “there are other strains that are dominant in other parts of the country,” Spitters said. “So this is a multifocal problem, not something that just spread from a single introduction.”

Some antibody tests have dubious reliability and generate false results, and even good ones aren’t foolproof and can’t pinpoint exactly when someone was exposed to the virus. Scientists also aren’t sure whether the presence of COVID antibodies in someone’s blood affords immunity or protection against reinfection.

To count positive antibody tests as a “probable” COVID case, current public-health surveillance guidelines require additional clinical symptoms or epidemiologic links to a confirmed case.

Washington State Department of Health officials said they encourage, but don’t require, local health districts to investigate positive antibody test reports. The Snohomish County district has received an additional 20 to 30 positive antibody reports that it has yet to investigate, Spitters said.

With limited public-health resources focused on suppressing the virus’ spread, state and local public-health officials said it’s difficult to retroactively investigate each positive antibody report or previous deaths caused by illnesses similar to COVID-19 to determine whether any cases predated the first known case.

“That certainly is of academic and scientific interest to me and many people,” Spitters said. “Someday maybe that work will be done, but it’s not a priority for the disease control moving forward.”


We want to hear from you about coronavirus antibody tests

What questions do you have about antibody testing? Have you tried to get tested? Ask your questions or share your experiences below and we may be in touch for one of our upcoming stories.