04-18-2020, 09:24 PM
Mystery In Wuhan:
Recovered Coronavirus Patients Test Negative ... Then Positive
March 27, 20209:28 AM ET
![[Image: gettyimages-1207338403-50_custom-6a61ff8...00-c85.jpg]](https://media.npr.org/assets/img/2020/03/27/gettyimages-1207338403-50_custom-6a61ff843275eac91af8fa6482efcff08402d1a5-s1100-c85.jpg)
People in Wuhan, China, line up at a facility that tests discharged COVID-19
patients as well as individuals who had been held in isolation.
Feature China/Barcroft Media via Getty Images
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 firstand 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.
Recovered Coronavirus Patients Test Negative ... Then Positive
March 27, 20209:28 AM ET
People in Wuhan, China, line up at a facility that tests discharged COVID-19
patients as well as individuals who had been held in isolation.
Feature China/Barcroft Media via Getty Images
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 firstand 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.
Semper Fidelis
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