Home / news / Even if you test negative for COVID-19, assume you have it, experts say: Conventional diagnostic tests for the novel coronavirus may give false-negative results about 30% of the time

Even if you test negative for COVID-19, assume you have it, experts say: Conventional diagnostic tests for the novel coronavirus may give false-negative results about 30% of the time

Even if you test negative for COVID-19, assume you have it, experts say: Conventional diagnostic tests for the novel coronavirus may give false-negative results about 30% of the time

View Reddit by maxwellhillView Source

35 comments

  1. Sensitivity of 70% sucks for a diagnostic.

    What the hell.

  2. I assume everyone else has it.

  3. if someone tests positive for influenza a… can they ALSO have covid at the same time?

  4. I mean, if you test negative also realize you can still get it, it’s not like millions of people are in the clear, and until we have an antibody test we won’t know for sure how many people are through Covid19, so only positive and recovered numbers mean anything (till we have the antibody test)

  5. Medical technologist here who currently works on the wet bench testing Covid19 cases!

    I don’t know what’s considered “conventional” in this context here.. but the assay my lab is using currently boasts at minimum a 95% sensitivity. The technique we use is a reverse transcriptase real time polymerase chain reaction with CDC primers. Although the validation for the test was done quickly, the team made sure it was a sound method before implementing it in a clinical setting. And any edge cases are always sent for repeat before confirming anything. There is absolutely no way we would consider 70% sensitivity acceptable for our patients/staff.

  6. 70% of the time, it works all the time.

  7. Then wtf are they making them for?

  8. Misleading and not news. Not enough training of staff is one issue for false negatives.
    Also, diagnostics are still about taking swabs from the throat, but the virus may already have moved on to the lungs, making the swab come back negative.

  9. “I get the roundabout coronavirus test. I call up my friend Brian, and say “Brian, do you know anyone with coronavirus? No? Cool. Cause you know me”

  10. Serious question, someone close to me had a fever and some respiratory issues a few days ago. The doctor recommended the she get tested and she agreed. So she got the test and was told to remain home and basically act under the assumption that she has COVID-19. She was told that the results of the test would take about 2 weeks and that she should only come to the ER if her symptoms get to the point where she’s having difficulty breathing.

    She’s a young and healthy person without any complicating pre-existing conditions, so she isn’t freaking out, but what is the point of having the test if she does not get the results for 2 weeks? If you’re acting under the assumption that you tested positive regardless, and the test takes 2 weeks – you essentially are being tested to let you know that you HAD the virus, not that you have it. What benefit does that information actually have at that point?

  11. Wait wait so its not China sending out faulty tests but just the way the virus is? And the ones here could be worse? Why isnt this headline news?

  12. When it takes two weeks to get results you have no choice but to assume you have it.

  13. Someone I know is likely in that 30%. Tested neg for Type A & B influenza. Has symptoms of coronavirus, thankfully not serious though, and recent proximity to someone who did test positive. Doctor told them to behave like they have it.

  14. “I tested negative for Covid-19!” “Where did you get tested?” “In the hospital!” “Erm, I’ve got some news for you.”

  15. Ok, now what? Do I die now?

  16. My wife tested negative but had almost all the symptoms for two weeks. However, no fever, which is seen in 87% of cases, so we’re not very confident that it was indeed covid. On the other hand, she did describe her coughing as the worst ever and that while coughing it felt like she might die. Fortunately she’s back to almost full health. I and our kids have zero symptoms, so either she was really negative, or we are asymptomatic. I kind of wish it was the latter… But at this point, we may never know for sure.

  17. My daughter and I tested negative and I swear we both have it (I have another daughter who got it as well). We’ve been coughing for 4 weeks. Had all the symptoms. Tested negative for flu and 17 other respiratory diseases including whooping cough.

  18. So can anyone tell me if the false positives are happening with the CDC-approved tests, the WHO tests, the “rapid” tests or any of the other tests? Or all of the above?

  19. It’s important to remember that in countries like the US, there is no standard test. Several different kinds are being used and their sensibility and sensitivity vary but also, depending on the stage of the infection, a sample from a patient’s mucus might not yet contain Covid 19. A patient who has a positive test of a bronchial wash, might not have enough viral load yet to be positive in the typical nasal swab.

  20. So everyone has it if we follow this belief….

  21. Something that is never mentioned in connection to this 30% number:

    If a swap is taken, that actually contains the virus’ RNA, the test will almost always be positive. The reason for this drop in accuracy is the amount of virus contained in each sample. Usually samples are taken from a person’s throat, but as the disease progresses, the virus concentration changes in this area. The virus travels downwards and attacks lung tissue and that’s why when people are tested through throat swaps these tests can be negative even though the person itself is infected. The virus simply isn’t in the throat anymore, it’s in the lungs.

    Source: Christian Drosten (German virologist, who developed the test)

    [https://www.youtube.com/watch?v=_WczFgyh1X4](https://www.youtube.com/watch?v=_WczFgyh1X4)

    (it’s in German, if someone can add an English source, I will be grateful. He only mentions this briefly but has expanded on this more broadly in another version of the podcast)

  22. Not only that but the tests are taking 3-5 days to result. If you have been in a clinic or hospital it’s very possible you’ve contracted it after your nasal swab. Almost pointless to test without rapid results

  23. This guy at my wife’s hospital came in with the symptoms. All of them, they just knew it had to be covid. Tests negative, but they were sure it had to be, only positive at 5th!! test.

  24. Why the fuck test at all then.

  25. So what’s the point in the test? Just assume you have it regardless.

  26. Fantastic news as I sit here waiting for results for the third day.

  27. Ok so everyone has it, let’s all jump off a bridge and end this thing once and for all.

  28. This is why the obsession with mass testing and case counts is stupid. Every slightly suspect case should be treated like a positive one. Self isolate, don’t go out and you’ll likely recover. If it gets worse go see a doctor.

  29. This is very strange – PCR Technology is extremely robust.

  30. Caution: Headlines are getting more longer and fucked up by the day.

  31. See, this is why people don’t believe in science. You CANNOT tell people “test, test, test” is the solution and then immediately turn around and proclaim these tests are useless and just assume one has the virus.

    Freakin idiots.

Leave a Reply