t*****r
发帖数: 543 | 1 Mystery In Wuhan: Recovered Coronavirus Patients Test Negative ... Then
Positive
A spate of mysterious second-time infections is calling into question the
accuracy of COVID-19 diagnostic tools even as China prepares to lift
quarantine measures to allow residents to leave the epicenter of its
outbreak next month. It's also raising concerns of a possible second wave of
cases.
From March 18-22, the Chinese city of Wuhan reported no new cases of the
virus through domestic transmission — that is, infection passed on from one
person to another. The achievement was seen as a turning point in efforts
to contain the virus, which has infected more than 80,000 people in China.
Wuhan was particularly hard-hit, with more than half of all confirmed cases
in the country.
But some Wuhan residents who had tested positive earlier and then recovered
from the disease are testing positive for the virus a second time. Based on
data from several quarantine facilities in the city, which house patients
for further observation after their discharge from hospitals, about 5%-10%
of patients pronounced "recovered" have tested positive again.
Some of those who retested positive appear to be asymptomatic carriers —
those who carry the virus and are possibly infectious but do not exhibit any
of the illness's associated symptoms — suggesting that the outbreak in
Wuhan is not close to being over.
NPR has spoken by phone or exchanged text messages with four individuals in
Wuhan who are part of this group of individuals testing positive a second
time in March. All four said they had been sickened with the virus and
tested positive, then were released from medical care in recent weeks after
their condition improved and they tested negative.
Two of them are front-line doctors who were sickened after treating patients
in their Wuhan hospitals. The other two are Wuhan residents. They all
requested anonymity when speaking with NPR because those who have challenged
the government's handling of the outbreak have been detained.
One of the Wuhan residents who spoke to NPR exhibited severe symptoms during
their first round of illness and was eventually hospitalized. The second
resident displayed only mild symptoms at first and was quarantined in one of
more than a dozen makeshift treatment centers erected in Wuhan during the
peak of the outbreak.
But when both were tested a second time for the coronavirus on Sunday, March
22, as a precondition for seeking medical care for unrelated health issues,
they tested positive for the coronavirus even though they exhibited none of
the typical symptoms, such as a fever or dry cough. The time from their
recovery and release to the retest ranged from a few days to a few weeks.
Could that second positive test mean a second round of infection?
Virologists think it is unlikely that a COVID-19 patient could be re-
infected so quickly after recovery but caution that it is too soon to know.
Under its newest COVID-19 prevention guidelines, China does not include in
its overall daily count for total and for new cases those who retest
positive after being released from medical care. China also does not include
asymptomatic cases in case counts.
"I have no idea why the authorities choose not to count [asymptomatic] cases
in the official case count. I am baffled," said one of the Wuhan doctors
who had a second positive test after recovering.
These four people are now being isolated under medical observation. It is
unclear whether they are infectious and why they tested positive after their
earlier negative test.
It is possible they were first given a false negative test result, which can
happen if the swab used to collect samples of the virus misses bits of the
virus. Dr. Li Wenliang, a whistleblowing doctor who later died of the virus
himself in February, tested negative for the coronavirus several times
before being accurately diagnosed.
In February, Wang Chen, a director at the state-run Chinese Academy of
Medical Sciences, estimated that the nucleic acid tests used in China were
accurate at identifying positive cases of the coronavirus only 30%-50% of
the time.
Another theory is that, because the test amplifies tiny bits of DNA,
residual virus from the initial infection could have falsely resulted in
that second positive reading.
"There are false positives with these types of tests," Dr. Jeffrey Shaman, a
professor of environmental health sciences at Columbia University, told NPR
by email. Shaman recently co-authored a modeling study showing that
transmission by individuals who did not exhibit any symptoms was a driver of
the Wuhan outbreak.
How real is China's recovery?
On Tuesday, Hubei province, where Wuhan is the capital, said it would relax
lockdown measures that have now been in place for more than two months and
begin letting residents leave cities the following day. Wuhan said it would
begin lifting its quarantine measures and letting residents leave two weeks
later, on April 8.
To leave Wuhan, residents must first test negative for the coronavirus,
according to municipal authorities. Such screenings will identify some
remaining asymptomatic virus carriers. But the high rate of false negatives
that Chinese doctors have cited means many with the virus could pass
undetected.
Last Thursday, Wuhan reported for the first time since the outbreak began
that it had no new cases of the virus from the day before — a milestone in
China's virus containment efforts. The city reported a zero rise in new
cases for the following four days.
Assessing asymptomatic carriers
But Caixin, an independent Chinese news outlet, reported earlier this week
that Wuhan hospitals were continuing to see new cases of asymptomatic virus
carriers, citing a health official who said he had seen up to a dozen such
cases a day.
Responding to inquiries about how the city was counting asymptomatic cases,
Wuhan's health commission said Monday that it is quarantining new
asymptomatic patients in specialized wards for 14 days. Such patients would
be included in new daily case counts if they develop symptoms during that
time, authorities said.
"Based on available World Health Organization data, new infections are
mainly transmitted by patients who have developed symptoms. Hence [
asymptomatic cases] may not be the main source of transmission," the
commission said.
A researcher at China's health commission told reporters Tuesday that
asymptomatic carriers "would not cause the spread" of the virus. Zunyou Wu,
the researcher, explained this was because the authorities were isolating
people who had close contact with confirmed patients. Wu did not explain how
they would identify asymptomatic carriers who had no close contact with
confirmed patients.
Addressing growing public concern of asymptomatic patients, China's Premier
Li Keqiang urged during Thursday's senior-level government meeting that "
relevant departments must ... truthfully, timely, and openly" answer
questions, such as whether these patients are infectious and how the course
of the outbreak may change.
Research suggests that the spread can be caused by asymptomatic carriers.
Studies of patients from Wuhan and other Chinese cities who were diagnosed
early in the outbreak suggest that asymptomatic carriers of the virus can
infect those they have close contact with, such as family members.
"In terms of those who retested positive, the official party line is that
they have not been proven to be infectious. That is not the same as saying
they are not infectious," one of the Wuhan doctors who tested positive twice
told NPR. He is now isolated and under medical observation. "If they really
are not infectious," the doctor said, "then there would be no need to take
them back to the hospitals again."
Geoff Brumfiel contributed reporting from Washington, D.C.
Copyright 2020 NPR. To see more, visit NPR. | l******t
发帖数: 55733 | 2 这种玩意就不要看什么npr了。南山说了，确诊病例一直在下降，肯定是控制住了，零
星火苗肯定免不了，现在网格监控依然执行中，翻不起大波浪 | n****l
发帖数: 1739 | 3 nothing mysterious about it. the testing kits are shit,
the ccp is shit, the little generals in Military are shit. | n****e
发帖数: 1403 | 4 照你这么说，我帝那是啥？
【在 n****l 的大作中提到】
: nothing mysterious about it. the testing kits are shit,
: the ccp is shit, the little generals in Military are shit.
| a******9
发帖数: 20431 | 5 shit of shits
【在 n****e 的大作中提到】
: 照你这么说，我帝那是啥？
| c******s
发帖数: 1 | 6 恐怖是中共的试剂盒不准吧！
of
one
【在 t*****r 的大作中提到】
: Mystery In Wuhan: Recovered Coronavirus Patients Test Negative ... Then
: Positive
: A spate of mysterious second-time infections is calling into question the
: accuracy of COVID-19 diagnostic tools even as China prepares to lift
: quarantine measures to allow residents to leave the epicenter of its
: outbreak next month. It's also raising concerns of a possible second wave of
: cases.
: From March 18-22, the Chinese city of Wuhan reported no new cases of the
: virus through domestic transmission — that is, infection passed on from one
: person to another. The achievement was seen as a turning point in efforts
| l******t
发帖数: 55733 | 7 屎坏了
【在 n****e 的大作中提到】
: 照你这么说，我帝那是啥？
| B*Q
发帖数: 25729 | 8 南山就算了吧
这回奉旨算命
老脸丢光了
[在 lsunspot (小手) 的大作中提到：]
:这种玩意就不要看什么npr了。南山说了，确诊病例一直在下降，肯定是控制住了，零
:星火苗肯定免不了，现在网格监控依然执行中，翻不起大波浪
:☆ 发自 iPhone 买买提 1.24.11 | B*Q
发帖数: 25729 | 9 这个全世界都知道了
[在 clearjks (clearjks) 的大作中提到：]
:恐怖是中共的试剂盒不准吧！
:one | l******t
发帖数: 55733 | 10 哪部分脸丢光了说来听听
【在 B*Q 的大作中提到】
: 南山就算了吧
: 这回奉旨算命
: 老脸丢光了
: [在 lsunspot (小手) 的大作中提到：]
: :这种玩意就不要看什么npr了。南山说了，确诊病例一直在下降，肯定是控制住了，零
: :星火苗肯定免不了，现在网格监控依然执行中，翻不起大波浪
: :☆ 发自 iPhone 买买提 1.24.11
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