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发帖数: 43471 | 1 Seattle researcher debunks theory COVID-19 spread in Calif. in November
SEATTLE -- A prominent Seattle medical researcher took to Twitter Sunday to
debunk a theory that the new coronavirus had been spreading in California in
November weeks ahead of the first known cases and that many in the state
have now developed "herd immunity" due to earlier exposure.
Trevor Bedford, a Fred Hutchinson Cancer Center scientist who made waves
near the start of the outbreak for sounding the alarm that the virus had
been silently spreading for weeks in the Seattle area, says his research
with the Seattle Flu Study shows there was no earlier California outbreak.
"This is empirically not the case," Bedford tweeted as part of an 18-tweet
thread detailing his evidence. "COVID-19 was first introduced into the USA
in Jan/Feb 2020."
Trevor Bedford
✔
@trvrb
There is a lot of Twitter chatter surrounding a rumor that circulation of #
COVID19 in California in fall 2019 has resulted in herd immunity. This is
empirically not the case. COVID-19 was first introduced into the USA in Jan/
Feb 2020. 1/18
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The theory surfaced last week as a possible explanation to why California
has had a less severe COVID-19 outbreak than New York, despite having double
the population and a weeks-long head-start on the virus' spread.
According to a tally kept by the New York Times, California has reported
just over 23,000 cases with 676 deaths as of early Monday morning, while New
York has had nearly 190,000 cases and 9,385 deaths.
The theory went that COVID-19 might have begun spreading in California in
November, masked as an early flu season. And if so, many Californians would
have already had the virus and now be immune to the current outbreak, thus
limiting the number of cases.
Bedford says evidence from his Seattle Flu Study shows that theory is
incorrect. The study had collected virus samples from volunteers around the
Seattle area as part of an original goal of tracking the spread of flu and
other respiratory ailments over the fall and winter.
The flu study team went back and retested their samples between Jan. 1 and
March 10 from patients who reported acute respiratory issues and flu-like
symptoms.
"We tested 3600 samples collected in Jan 2020 for COVID-19 status and found
zero positives," Bedford tweeted. "We tested 3308 samples collected in Feb
2020 and found a first positive on Feb 21 with a total of 10 samples testing
positive in Feb."
Trevor Bedford
✔
@trvrb
· Apr 12, 2020
Replying to @trvrb
All samples were from individuals suffering acute respiratory infection with
a subset having influenza-like illness. Individuals with undiagnosed COVID-
19 should be picked up with these symptom criteria. 4/18
Trevor Bedford
✔
@trvrb
We tested 3600 samples collected in Jan 2020 for COVID-19 status and found
zero positives. We tested 3308 samples collected in Feb 2020 and found a
first positive on Feb 21 with a total of 10 samples testing positive in Feb.
5/18
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He added that even going back into October, they study found a variety of
respiratory illnesses circulating in the region, from flu, rhinovirus and
other seasonal coronaviruses that are "easily distinguishable" from COVID-19.
"There is no chance of confusion between these in our assay," Bedford
tweeted. "It's empirically true that the Seattle flu season in Oct through
Jan was not the result of COVID-19. We would have seen it in these data.
Given travel connections between WA and CA there is no way that COVID-19 was
widely circulating in CA, but we see zero cases in WA."
In addition, tracing the virus' genetic roots also paints a clear picture
that the virus did not enter the United States until January.
"There were multiple paths the virus took to reach the US. There was a
direct introduction from China that occurred in late Jan and there were
multiple introductions from the European epidemic that occurred during the
course of Feb.," Bedford tweeted, adding the data shows the California
outbreak fell in line with the rest of the U.S epidemic. "There is no chance
SARS-CoV-2 was circulating in California in fall 2019. Circulation in CA
started in Jan or Feb 2020."
Trevor Bedford
✔
@trvrb
· Apr 12, 2020
Replying to @trvrb
We can use the number of genetic changes observed in a viral lineage to
estimate the date of its common ancestor. 10/18
Trevor Bedford
✔
@trvrb
There have been hundreds of viruses sequenced from infections in the USA. We
can use these sequences to date the arrival of the epidemic. Doing so, we
see that there were multiple introductions driving the US epidemic and the
earliest was in Jan. https://nextstrain.org/ncov/global?f_country=USA … 11/
18
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Bedford concludes that his calculations shows that COVID-19 infections in
the U.S. are far short of the level needed to obtain "herd immunity." He
continued to advocate the best way out is to increase testing to where we
can isolate those who are infected and those who have had direct exposure. | d********f
发帖数: 43471 | 2 我了解对大外宣这么长的英文很难
We tested 3600 samples collected in Jan 2020 for COVID-19 status and found
zero positives. We tested 3308 samples collected in Feb 2020 and found a
first positive on Feb 21 with a total of 10 samples testing positive in Feb.
5/18
这段你能看懂就好
to
in
【在 d********f 的大作中提到】
: Seattle researcher debunks theory COVID-19 spread in Calif. in November
: SEATTLE -- A prominent Seattle medical researcher took to Twitter Sunday to
: debunk a theory that the new coronavirus had been spreading in California in
: November weeks ahead of the first known cases and that many in the state
: have now developed "herd immunity" due to earlier exposure.
: Trevor Bedford, a Fred Hutchinson Cancer Center scientist who made waves
: near the start of the outbreak for sounding the alarm that the virus had
: been silently spreading for weeks in the Seattle area, says his research
: with the Seattle Flu Study shows there was no earlier California outbreak.
: "This is empirically not the case," Bedford tweeted as part of an 18-tweet
| i**t
发帖数: 921 | 3 大外宣不识阴文
Feb.
【在 d********f 的大作中提到】
: 我了解对大外宣这么长的英文很难
: We tested 3600 samples collected in Jan 2020 for COVID-19 status and found
: zero positives. We tested 3308 samples collected in Feb 2020 and found a
: first positive on Feb 21 with a total of 10 samples testing positive in Feb.
: 5/18
: 这段你能看懂就好
:
: to
: in
| d**e
发帖数: 1124 | 4 数据很明显啊
2月21日以前几千个流感样品全是阴性
美帝如果2019年就有新冠，恐怕1月底早就爆了 | d********f
发帖数: 43471 | |
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