Irene Hartmann
07/03/2020 - 15:54
- Clarín.com
- Society
A few days ago it was learned that the Buenos Aires Government had withdrawn 20,000 serological tests of antibodies against the coronavirus due to alleged failures that "jumped" after eight false positives were detected at the Muñiz Hospital. Then, the Buenos Aires Ministry of Health explained that the tests of the questioned lot made up a batch of 100,000 identical tests, of which only 20% had been distributed, and that they had been purchased from the SD Biosensor company . Clarín contacted that Korean company, from where they explained that the reagents have a " perfect performance " and that the inconvenience was due to improper use of these serological tests, something that was also confirmed from the environment of Minister Fernán Quirós.
The questioning that led to the return of 20,000 tests that had been distributed to Buenos Aires hospitals and that put in check the use of another 80,000 of the same game, had arisen due to an inconsistency in the results of eight of those tests (which determine the presence of two antibodies against Covid-19: Igm and Igg ), when compared with the PCRs subsequently made to these people.
As Clarín explained at the time, high levels of Igm indicate that the infection is supposedly ongoing. However, while in that case a PCR (swab) molecular test should be positive, they gave the opposite result.
What happened? Roxana Jung, regional manager of SD Biosensor, responded through a dedicated email that, after "asking for evidence, talking to the technicians and starting an investigation", it was concluded that the performance of these kits is "perfect", and that In reality, " users were not following the recommendation ."
The "users" is the Hospital Muñiz. Jung explained it like this: “Our tests are supplied with a protective film , to standardize environmental conditions such as humidity and temperature; and we concluded that users were not following the recommendation and used the test without the corresponding film. "
Basically, the cold or the evident humidity these days caused that the blood taken from the prick in the finger with which these tests are done "did not migrate well to the cassette " , clarifies Jung, referring to the reactive "band aid" (who some Once you've seen a pregnancy test you'll understand this analogy.)
In the detailed email written in English, Jung clarifies that this "was also publicly confirmed by the Minister of Health of the City of Buenos Aires, Dr. Fernán Quirós." This Friday, from Salud de la Ciudad they confirmed that, clarified the error, the other 80,000 tests of the indicated game are being distributed normally .
Points of view
The SD Biosensor email also offers an explanation of the misuse that, from the company's point of view, made the concept of "false positive" in the Argentine media and on the part of the health experts who warned of the batch " failed. "
The Buenos Aires Minister of Health, Fernán Quirós, agreed that the failures of the serological tests against Covid-19 were due to a misuse of these diagnostic tests.
“Regarding false positive calls, please note that after selling our product in more than 60 countries, we had no complaints about that problem. Our Q DUO COVID standard detects, qualitatively, two types of antibodies, IgM and IgG; proteins produced by our immune system, as a protective response to Covid-19 infection (…) PCR detects the genomic material of the virus, so these methods take different 'photos' and cannot be compared, ”he clarified.
Thus, he continued, "the results with a single diagnostic method - only PCR or only antibodies - would lead to misunderstandings in the interpretation for the diagnosis of coronavirus, if there is no start date for the patient's symptoms." Jung assured that to have an accurate diagnosis, both tests must be performed at the same time, since the levels of IgM and IgG in the human body "change continuously every day, depending on the date of onset of the symptom."
What is Coronavirus? How is it spread and what are its symptoms?
Watch the special"What if these eight patient samples had been collected after three weeks from the symptom onset date? Would the PCR results have negative results and would our Duo IgM / IgG have positive results? ”Asked Jung. However, those tested had not had any symptoms: they had been tested as part of the Buenos Aires strategy of finding " seroconversion " with weekly check-ups on health personnel.
Hence the importance of having tests in good condition that are also used properly. As Minister Quirós explained in a press conference this week, "looking for seroconversion is central because when someone who was negative becomes positive, we can arrive early to isolate him and quickly detect an outbreak."
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