She came down with a bug two days after Christmas, and for the next week or so, Jean, a 64-year-old retired nurse, suffered through a series of worsening symptoms: a dry, hacking cough, a fever and body aches, and finally, a wheeze that rattled her lungs.

But after two trips to the doctor, chest X-rays and prescriptions for several medications, including a “DuoNeb” solution inhaled through a nebulizer device commonly used to treat asthma, her condition slowly improved.

Months later, after the novel coronavirus pandemic had exploded across Western Washington, the nation and into American consciousness, Jean and dozens of others like her, have wondered if their early winter colds really were undiagnosed cases of COVID-19, the illness caused by the virus. But her case didn’t seem to fit the profile. She hadn’t traveled abroad, and the official timeline was off: The first known patient infected by COVID-19 — a Snohomish County man who’d recently traveled to China — wasn’t even confirmed until more than three weeks after she became ill.

“When I got sick, I didn’t even know what COVID-19 was,” said Jean, a resident of rural Snohomish County who asked only to be identified by her middle name.

But after Jean received word from her doctor earlier this month that a highly touted serology test found a sample of her blood positive for antibodies to COVID-19, she’s now convinced the official timeline is wrong — and public health officials say she may be right.

Jean is among two Snohomish County residents who have positive serology tests potentially linked to COVID-like illnesses dating back to December, throwing into question whether the coronavirus arrived in Washington, and the United States, earlier than previously known.

Although neither case offers ironclad proof of that – an antibody test can’t pinpoint exactly when someone was exposed to the virus – each patient’s test results, combined with the clinical symptoms in December, appear to meet the federal Centers for Disease Control and Prevention’s (CDC) case definitions for COVID-19.

“They are being considered ‘probable,’” Heather Thomas, a Snohomish Health District spokeswoman, said in an email Thursday. “However, they are not captured in our case counts from Jan. 20 forward.”

After The Seattle Times asked about Jean’s case this week, the local health district said it had a second positive antibody case involving a person who showed symptoms in December, but provided no further details. Thomas said the district’s health officer, Dr. Chris Spitters, is planning to talk about the cases during a Friday news briefing. A brief report accounting for all of the district’s known reports of positive antibody tests, about 30, would be issued, Thomas said.

The two cases provide more circumstantial fodder to mounting doubt among medical doctors, research scientists and others that the Snohomish County man who tested positive on Jan. 20 is the purported Patient Zero who introduced the coronavirus to the U.S. The man had been traveling solo since November in Wuhan, China, where the outbreak appears to have originated. He returned to the Seattle area on Jan. 15 and days later began showing symptoms.

“My own guess is that there wasn’t one introduction or Patient Zero who brought the virus to the United States,” said Dr. Art Reingold, a public health epidemiologist at the University of California at Berkeley. “There were likely earlier and multiple introductions of the virus.”

Timeline uncertain

Because the virus’s undetected spread in Washington and elsewhere predated broad testing in the United States, a definitive timeline for COVID-19-related cases and deaths remains in question, scientists say.

Already, studies in other nations have poked holes in what previously were thought to be starting points for the virus. Researchers in France recently found a COVID-19 case dating to Dec. 27 — nearly a month before that nation’s first previously confirmed case on Jan. 24. A genetic study published by researchers in Britain this month also found evidence to support “extensive worldwide transmission of COVID-19” likely infecting people in the U.S., Europe and elsewhere weeks or possibly months before some of the first reported cases in January and February.

“The amount of air travel into and out of Wuhan was enormous, probably thousands and thousands of people,” Reingold said. “It follows that there was likely multiple introductions around the world, quite possibly in December.”

Likewise, a timeline for COVID-19-related deaths in the U.S. has been pushed backward. A resident of the LifeCare Center of Kirkland who died Feb. 26 initially was believed to be the first death, but retrospective autopsies of two people in Santa Clara County, California, in April revealed each had died from the illness earlier, with the first death occurring on Feb. 6. That discovery prompted California Gov. Gavin Newsom to direct local medical examiners and coroners to investigate whether COVID may have claimed anyone in the state even earlier — as far back as December.

Washington state also has reviewed some cases of those who died from pneumonia or respiratory illnesses, but so far hasn’t found any that predate the first confirmed COVID-19 case in January, State Health Officer Dr. Kathy Lofy said. The King County Medical Examiner’s Office retrospectively tested 20 bodies in its morgue, but none were confirmed positive. Public Health – Seattle & King County said it is reviewing medical records for some individuals who may have contracted the disease early this year. Medical examiners and coroners elsewhere in the state are considering retrospective testing of tissue and blood samples from earlier cases, but the state so far hasn’t directed such reviews.

Local and state public health officials also say they don’t have much capacity to investigate whether individuals like Jean, who receive positive antibody test results, may have had COVID-19 earlier than the first known case.

“It’s always interesting to go back and find out how things have started, but it’s hard to put those pieces together,” Lofy said. “I think a lot of our focus now is on the current spread of the virus and stopping new transmissions.”

As far as including positive antibody tests in daily case counts, public health agencies in Washington don’t yet appear to be on the same page. The CDC’s case definitions note “serologic methods for diagnosis are currently being defined,” but also list someone with a positive serology test as a “presumptive” case. That means to be formally counted, the person must also have had certain clinical symptoms at some point, or close contact with a confirmed or probable case of COVID-19 — details that require additional investigation to find out.

“Local health jurisdictions are encouraged to investigate patients with positive antibody results if they have the resources, but these investigations are not required,” state Department of Health (DOH) spokeswoman Lisa Stromme Warren said.

Still, DOH said it now counts antibody tests as “probable cases,” but the dates reported for them may vary based on when test results came back or on when symptoms or ties to other cases occurred.

The Snohomish Health District has received other reports of positive antibody tests, “but case investigations on those are a lower priority in follow-up, as our focus is on current cases,” Thomas said.

A Public Health — Seattle & King County spokesman said that agency isn’t now counting positive antibody tests in its daily counts, noting CDC guidance remains pending and there is “high potential for false negatives and positives” in serology tests.

Although a number of antibody tests have been found to be unreliable, the test Jean received — designed by Abbott Laboratories and now widely performed by the UW Medicine Virology Lab — is considered highly accurate. But even correct antibody test results can’t say for sure when someone was infected with the virus. For instance, Jean’s cold in late December could have been caused by a different virus, and she may have picked up an asymptomatic or mild case of COVID-19 sometime later, scientists and health officials said.

Other than that bad cold, “I didn’t get sick any other time,” Jean said. “If I didn’t get the virus then, I can’t imagine when I would’ve gotten it.”

If any Washington cases predated the first known case, there were probably very few that didn’t multiply, said Dr. Jared Roach, a senior research scientist at the Institute for Systems Biology, a Seattle-based biomedical research firm.

The Seattle Flu Study’s comprehensive assessment of nasal specimens collected in the Seattle area between January and March detected only 25 COVID cases out of more than 2,353 samples. That included what was then the first known case of community transmission on Feb. 24 — a Snohomish County teen who was infected by a SARS-CoV-2 strain with a genetic sequence found to be nearly identical to that of first known case in January.

Genetic sequencing of multiple cases from the Western Washington outbreak by Nextstrain, an open-source genome data project, further indicates “there is not a lot of support for an earlier, independent event,” Roach said.

But that doesn’t rule out the possibility that isolated transmissions infected some people earlier, but simply didn’t spread widely, Roach said.

“If you think of transmission in terms of sparks landing on tinder, some of them land, but don’t catch. And then — boom — one of them does and starts a fire,” he said. “So, maybe there were a few early sparks in Western Washington.”

Troubling symptoms

In the weeks before she started feeling sick, Jean said she didn’t leave home much.

She met a friend for lunch in Snohomish, did some grocery shopping and attended a holiday lighting event. She also visited her rheumatologist’s office in Seattle, telling him she wanted to change a medication for her arthritis that suppressed her immune system and caused bad side effects.

Her cough started two days after Christmas. After her condition worsened on Jan. 4, a doctor found her lungs hyperinflated, put her on an asthma course and advised her to get her lungs checked in a month, medical records show.

When she was feeling well enough, Jean and her husband traveled to Utah to visit their daughter’s family, staying for several weeks. An early February check-up with a doctor there showed she’d fully recovered, with a breathing test giving her the lung age of a 45-year-old.

After returning home, she met a friend — a nurse from a Bellevue hospital — in Kirkland, a few miles from the nursing home where a deadly outbreak occurred about two weeks later.

“My friend hasn’t been sick, but is it possible I picked up something in Kirkland?” Jean asked. “I guess.”

But more likely, she suspects, the cold she caught in late December that caused her to cough up blood and throttled her breathing was COVID-19.

“I told people, if that wasn’t coronavirus I had, then I’ll be dead if I really do get it,” she said.

For weeks, Jean planned to get an antibody test, but opted to wait until a good one became available. In late April, she had her doctor take a blood sample and order the UW test. After results came back positive on May 1, she felt both fear and relief, she said.

“I understand that it’s not 100% and that there’s no guarantee that antibodies bring immunity,” she said. “But it gives me some peace of mind that if I get it again, I can survive.” [...]

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.

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.”