South Koreans re-diagnosed with coronavirus had false positive results
South Korea admits 292 coronavirus ‘reinfections’ were false positives as officials warn fragments of the virus can linger in the body for MONTHS
- Over the past month South Koreans cleared of the virus testing positive again
- The country was grappling with fears that people could be reinfected
- A infectious disease expert has claimed the results are due to a testing fault
- He said the test can pick up viral fragments left in the body even if inactive
- It relieves worries that immunity is short lived for people who have had the virus
- Here’s how to help people impacted by Covid-19
South Korean officials have today revealed 292 coronavirus patients feared to have been ‘reinfected’ were given false positive results.
Over the past month the Asian country has seen people cleared of the virus testing positive again, despite new cases thinning out.
Fears were raised the recovered cases had been reinfected from somebody else, or the virus had laid dormant before reactivating again.
Either way, it raised suspicions that a person’s immunity is short lived after fighting off the deadly virus, scientifically called SARS-CoV-2.
If humans had no immunity, easing draconian lockdowns would have been pointless because no-one would be protected from being struck down again.
A senior South Korean official has now said the flurry of ‘reinfected’ people was due to a testing fault – and not a short-lived immunity.
The infectious disease expert revealed dead virus fragments can remain in the body, possibly for months.
These lingering fragments may cause a positive result, even though the person is not sick or infectious anymore, health chiefs added.
Oh Myoung-don, who leads The Central Clinical Committee for Emerging Disease Control (pictured at a press conference on Wednesday) , said dead virus fragments that remain the body, possibly for months. These fragments may be picked up by tests
Over the past month the country has seen people cleared of the virus testing positive for the virus again, despite new cases thinning out (pictured, daily new cases)
Health authorities in South Korea have said they recorded no new domestic cases of coronavirus infections at the end of Wednesday. Pictured, people outside in Seoul on April 30
Health authorities in South Korea have said they recorded no new domestic cases of coronavirus infections at the end of Wednesday.
It was a first for the country – which bucked the global trend and avoided going into lockdown – since its outbreak began to worsen in February.
However, there were four new imported cases, said the Korea Centers for Disease Control and Prevention.
South Korea’s total death toll is up to 247 – a fewer than some European countries have been reporting each day.
Countries like the US, Italy, France, Spain and the UK each have at least 100 times the death toll of South Korea.
While those countries grappled with their outbreaks, South Korea was faced with a new problem: reinfections.
Epidemiologists in Seoul urgently tried to drill down into the cause of the worrying trend, which was first witnessed in 51 patients from Daegu on April 6.
Forty more coronavirus patients in South Korea thought to have recovered from the disease tested positive again on April 10.
HOW DID SOUTH KOREA CURB ITS OUTBREAK AFTER BEING THE WORST INFECTED COUNTRY OUTSIDE OF CHINA?
South Korea had its outbreak of coronavirus peak on February 29 when the country reported the world’s most infections outside China.
But it has been able to flatten its curve, reporting no new domestic coronavirus cases today, and just one death.
The country has been aggressive in its fight against COVID-19, from quietly developing and stockpiling test kits as early as January, to tapping into smartphone and credit card data to track the movements of those confirmed to have the virus.
The country tested up to 20,000 people a day for the virus, which would have allowed them to get an idea of how the virus was spreading.
Seoul started its testing programme when the numbers were still small, telling companies to develop testing kits as early as January 27.
The first diagnostic kit was approved on February 4, and nearly 100 laboratories are now equipped to carry out tests.
When cases started mounting around the Shincheonji church, officials said they would test every member of the sect.
The city of Daegu announced that nearly all the 10,000 worshippers had been tested by March 10.
South Korea was also a pioneer of contact tracing, using phone location data and smartphone apps to identify clusters of cases.
Mandatory testing and quarantines now apply to nearly all arrivals from overseas, including citizens.
South Korea installed testing facilities this month at Seoul’s Incheon International Airport to screen anyone who arrives with symptoms.
All arrivals must download a government app that tracks their location and requires users to report any symptoms.
Everyone must self-isolate for two weeks if they do report symptoms, regardless of nationality or whether they tested negative.
After the two-week period, the app shows a message saying users are free to delete it from their phones.
The government also rationed protective face masks among citizens and delivered care packages with food, water, hygiene products and masks to those in self-quarantine.
On April 27 it was reported at least 222 people were in the ‘reinfected’ category, as health officials scrambled to allay creeping nervousness that people can be re-infected.
Jeong Eun-kyeong, director of the Korea Centers for Disease Control and Prevention (KCDC), told a briefing that the virus may have instead been ‘reactivated’.
It would mean that the patient never completely fought the virus off due to a deficient immune response.
Scientists dismissed the idea it was due to a fault in testing, Hwang Seung-sik, a spatio-temporal epidemiologist at Seoul National University, told Al Jazeera News.
‘Few researchers think that this is actually a case of reinfection or an issue of accuracy in test kits,’ he said. ‘Many are looking at this more as a virus reactivation.’
‘Given the high accuracy of test kits and volume of testing being conducted, this many cases of reinfection or reactivation is not a high number.’
About 20 per cent of those known to have gotten sick again are in their 20s, with those in their 50s making up the second-largest group.
‘Rather than an error in test kits, I think this issue may be from a difference in immune system function between individuals,’ said Dr Roh Kyung-ho, who works at the Department of Laboratory Medicine at the National Health Insurance Ilsan Hospital.
‘We’re in a situation where there is still no effective treatment or cure for the virus, and people might vary in how long they emit the virus, whether it be one month or six weeks.’
But a clinical expert panel on Wednesday concluded that recovered coronavirus patients who later test positive for the virus again were not ‘reactivated’ or reinfected, but were false positives.
Oh Myoung-don, who leads The Central Clinical Committee for Emerging Disease Control, said he and colleagues found little reason to believe cases could be COVID-19 reinfections or reactivations.
The head of the committee said the false positives were due to technical limits of PCR testing.
PCR testing is considered the gold standard due to its high accuracy levels but there are varying levels of sensitivity
‘The tests detected the ribonucleic acid of the dead virus,’ Dr Oh, a Seoul National University hospital doctor, told a press conference held at the National Medical Center on Wednesday.
The panel noted that the Covid-19 infection and the viral proliferation occur in respiratory epithelial cells, which line surfaces in the lungs.
Viral fragments may exist in epithelial cells even after the virus is inactivated, according to the panel.
These cells have a half-life of up to three months, and RNA virus in the cell can be detected with PCR testing one to two months after the ‘elimination of the cell,’ Dr Oh said.
The PCR tests cannot distinguish whether the virus is alive or dead, and this can lead to false positives.
‘PCR testing that amplifies genetics of the virus is used in Korea to test COVID-19, and relapse cases are due to technical limits of the PCR testing,’ Dr Oh claimed.
Dr Oh said the coronavirus does not linger inside the nucleus of human cells.
In this respect the virus that causes COVID-19 is different from the HIV and hepatitis B viruses, which can remain dormant in cells and awaken later.
Dr Oh went on to say that it is highly unlikely someone would be reinfected again because evidence suggests immunity is maintained for one year after the first infection.
He said: ‘If we look at the results of the coronavirus (HCoV-229E) study on humans or the current Covid-19 virus (SARS-CoV2) study on animals, the immunity in vivo is maintained for more than one year after the first virus infection.
‘Thus, it is improbable that a person could contract another coronavirus.’
A clinical expert has now said the flurry of ‘reinfected’ people was due to a testing fault. The infectious disease expert said dead virus fragments that remain the body, possible for ‘weeks’, may cause a positive result, even if the person is not sick of infectious anymore.
The infectious disease expert said dead virus fragments that remain the body, possible for ‘weeks’, may cause a positive result, even if the person is not sick of infectious anymore. Pictured: A Buddhist believer wearing a faces mask during a service to pray for overcoming the COVID-19 outbreak at the Chogyesa temple in South Korea, April 30
The health authorities concluded no local transmission occurred from a parliamentary election this month, where authorities took safety measures, including requiring voters to wear masks and plastic gloves when casting ballots. Pictured: Buddhist believers at a service, April 30
Reinfections would have made global efforts to contain the virus much more daunting.
Although the news from South Korea today is hopeful that reinfections don’t exist, it cannot be ruled out completely.
Officials have been relying on hopes that once a person has had the coronavirus, they are protected from getting it again because their body has built up antibodies.
The idea of ‘immunity passports’, which certify a person has already had the bug, were at one point considered the key to getting out of worldwide lockdown.
But the World Health Organisation has warned against the idea because there is currently no evidence that people who have recovered from Covid-19 are free from the risk of a second infection.
The WHO added that tests for antibodies of the new coronavirus ‘need further validation’ to understand how long immunity lasts for.
South Korea today reported no new domestic coronavirus cases – a win for the country which has been battling the virus since February.
KCDC reported four new infections, all imported cases. Of the total, 1,065 have been imported cases, where more than 90 per cent were Koreans, according to a KCDC statement.
The health authorities also concluded no local transmission occurred from a parliamentary election this month, where authorities took safety measures, including requiring voters to wear masks and plastic gloves when casting ballots.
‘Twenty-nine million voters participated in the April 15 parliamentary election,’ Yoon Tae-ho, director general for public health policy, told a briefing.
‘Not one case related to the election has been reported during the 14 days of incubation period.’
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