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Apr. 25th, 2020 07:40 amHere's a thorough analysis of early COVID-19 cases in the SF Bay Area and Seattle:
As I wrote earlier, Hansen's theory about "November cases" was pure bullshit.
Dr. Chiu [UCSF] mapped several known strains of the virus in the 29 people who tested positive in Northern California between Feb. 3 and March 15. “Early infections disproportionately occurred in returning travelers,” he said.
The strain circulating aboard the Grand Princess cruise ship that docked in Oakland matched the first known U.S. infection in January. Two individuals from the same household in San Mateo County matched a strain from China. And other individuals from the same county matched strains circulating in Europe. Dr. Chiu’s research is being peer-reviewed.
In a separate study that hasn’t yet been reviewed, Dr. Chiu found 20 of the first 46 patients diagnosed at UCSF had traveled to places such as Europe and New York, among other U.S. cities. That dovetails with other research that found that early infections detected in California closely resemble strains earlier reported elsewhere, suggesting visiting or returning travelers introduced the infection rather than that it was circulating over time.
To examine the early spread of Covid-19—the disease caused by the virus—in the San Francisco Bay Area, researchers tested nasopharyngeal samples collected from people between Jan. 1 and Feb. 26. Those people sought care for respiratory problems at Stanford Health Care but tested negative for common respiratory viruses. Of the 2,888 patients screened, only two tested positive for Covid-19.
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A similar study of more than 6,900 people who reported flu-like symptoms in Seattle earlier this year detected its first Covid-19 infection in late February.
Doctors testing for antibodies, which show whether an individual was previously infected, do say the number of U.S. infections is grossly underestimated. Earlier this month, researchers estimated that 2.8% to 5.6% of Los Angeles County’s 10 million adults had been infected at some point.
Those numbers, however, are nowhere close to the levels typically needed for herd immunity of 50% or above, said Michael Busch, director of the Vitalant Research Institute, which is conducting a nationwide serology study funded by the National Institutes of Health. “I doubt we’ll see more than 5% to 10% of the U.S. population immune,” Dr. Busch said.
https://www.wsj.com/articles/has-coronavirus-been-in-california-since-the-fall-researchers-investigate-11587816001
As I wrote earlier, Hansen's theory about "November cases" was pure bullshit.
