It’s a comforting thought at a time of mass death from an historic and unpredictable pandemic: What if I had it already—maybe even that time I felt sick a few months ago?

After all, while antibody testing is only now being rolled out in any significant numbers—and its reliability remains in doubt—the hope is that having recovered from the illness might offer some measure of immunity to reinfection. And the documented prevalence of so-called “silent”—or asymptomatic—spreaders suggests many Americans have unknowingly been infected.

But public health experts told The Daily Beast that even if the virus was spreading in the United States earlier than the first confirmed case in Washington in mid-January, anyone hoping they had it as far back as November or December is likely to be disappointed.

KSBW, a local news station in Monterey, California, recently set off excitement about the idea of widespread undetected infection—and so-called “herd immunity”—when it covered a Stanford study to determine how many Californians may have already had COVID-19. The piece was widely shared and picked up by several other publications, including The San Francisco Chronicle.

“Something is going on that we haven’t quite found out yet,” Victor Davis Hanson, a senior fellow with Stanford’s Hoover Institute, said in an interview with the station.

Hanson, whose quotes anchor the story, pointed to last fall, when he said California doctors reported an earlier than usual rise in flu cases at the same time that the state was welcoming up to 8,000 Chinese nationals daily into its airports, many on direct flights from Wuhan, the original epicenter of the coronavirus outbreak.

But, as Slate reported after looking into the story, Hanson is not a doctor or scientist; instead he’s a military historian. He later explained in a podcast for the National Review that, while he mentioned the Stanford study, he never claimed to be involved in it—nor a doctor—and that the “left got mad” at his implication that “herd immunity” could justify loosening social-distancing guidelines.

On Friday, preliminary results from the Stanford study pointed to as many as 4.6 percent of the Santa Clara County population possibly having antibodies for the coronavirus—85 times the number of confirmed COVID-19 cases there. But experts told The Daily Beast that even those numbers are still a long way off from creating so-called herd immunity, and there was still little-to-no evidence of U.S. infections back in 2019.

“It’s possible but I wouldn’t say it’s very likely,” said Dr. William Haseltine, president of the global health think tank ACCESS Health International and former Harvard Medical School professor, who recently chaired the U.S.-China Health Summit in Wuhan, in an interview with The Daily Beast.

Those who lived in current COVID-19 hot spots back in the fall and had recently travelled from Wuhan or hard-hit areas in Europe, had an unusually bad cold with a prolonged fever, were tested for the flu and had the results come back negative—“maybe they had this,” was as far as Haseltine would go. But he remained skeptical that there were very many, if any, such cases that had not yet been detected.

“There is zero probability [SARS-CoV-2] was circulating in fall 2019,” tweeted Trevor Bedford, a computational biologist at Fred Hutchinson Cancer Research Center who has been tracking the virus’s genetic code as it has spread through the country.

To be clear, a study reported by The New York Times tracking viral mutations found that most coronavirus cases in the U.S. came via Europe, not directly from China—and that the virus began to circulate in the New York area by mid-February, weeks before the first confirmed case there. The Washington Post also reported on March 1 that researchers, including Bedford, had conducted genetic sequencing of SARS-CoV-2 in Washington state and found that the coronavirus had been circulating in the community for longer than originally believed.

“The [data] strongly suggests that there has been cryptic transmission in Washington State for the past 6 weeks,” said Bedford at the time he announced the results on Twitter, on Feb. 29. Later, however, Bedford told the Times that he was “quite confident,” based on newer data, that the virus was not spreading in December in the United States.

Unfortunately for a layperson hoping that a particularly bad cold or flu in the fall was the coronavirus, it probably wasn’t, according to Dr. Jeffrey Klausner, an adjunct professor of epidemiology at the University of California Los Angeles who previously worked for the CDC.

“If that person was in Wuhan, China, it’s likely. But in the United States, it’s extremely unlikely,” he said.