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Comment by wojcikstefan | Hacker News Reader

If I'm reading this right, the RNA of SARS-CoV-2 can be found in the upper respiratory tract for a very long time (even 83 days in the extreme case), but the live virus (capable of infecting others) was not discovered by any study beyond day 9.

Self-isolating/quarantining for 10 days after a positive test result, which many regions enforce, seems consistent with these findings (again, if I'm interpreting the results correctly).

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I agree but the key is to get test results quickly. A five day delay in getting test results (which is common) seems to imply that an infectious patient may have already done their worst spreading by the time they start quarantining.

In the UK, if you have a test, you are required to quarantine until you get the results. Is it not the case elsewhere??

In the US we don't really have "rules" so much as "suggestions"

It's probably the rules everywhere, but I imagine that compliance is a lot lower for people waiting for a test result than it is for people that received a positive test (especially those with mild symptoms)

In Australia that's the standard response too - if you're symptomatic (of anything vaguely resembling the wide range of COVID19 symptoms) then you a) isolate, and b) get a test, and c) isolate at least until the test results come back.

Not in .il, because of mass-testing efforts and people needing to show a negative result before travel and having no reason to believe they are positive.

Quarantine is mandatory if you had exposure or returned from abroad.

I'd hesitate to make it a rule because some people take them proactively, or even routinely. But yeah if someone has symptoms, or think they were exposed, that would make sense.

Not here in Poland.

Though, it would very logical as a precaution.

YES in Poland.

I know people in Poland who avoided getting a COVID19 test because they knew they would have to quarantine if they took the test, and would not have to quarantine if they didn't. That's perverse incentives for ya'.

It's very hard to enforce, of course, but if you get caught, there are (in abstract) severe fines.

In the US it sometimes takes up to two weeks to get a result, in which case the test is pointless.

Lest readers assume this is typical, where I live at present (middle of the US) testing is efficient. Our kids' school runs their own rapid tests also. You can in addition buy saliva PCR tests from many vendors including Costco. These take 3 days max from purchase to result.

Right. I had to get a Covid-19 test in October as part of groundwork for another procedure. I could've gotten a rapid test that gave results same day, or the PCR test. I got the PCR test (because more accurate) and had results back within 2 days.

In my town, if a child receives a positive test result, the whole classroom is under quarantine.

So it's not pointless in that sense. You know who might have been exposed.

It's also not pointless for monitoring spread.

Unless they quarantine preemptively from the time they're tested.

I agree accessibility and speed of testing is critical.

So help me understand. What about cases where somebody gets covid, goes to the hospital on day 15, respirator day 20, dies day 25.

Was somebody in that profile only contagious up until day 9?

Correct. Most of the “long Covid” effects appear to be more related to immune dysregulation as a response to the virus, causing the so-called cytokine storm and leading to damage in the lungs, heart, vasculature, etc. (Lots of support to this, I’ll look for a good review and update this post with an edit.)

Edit: https://www.medrxiv.org/content/10.1101/2020.05.27.20115238v...

Check out Figure 1 and the Discussion section for a good overview.

I think that everything you said regarding the "Long Covid" is correct, but I don't think that it necessarily follows that patients dying of covid ARDS have ended viral replication and are no longer contagious.

From what I understand the actual 'viral' phase of the disease isn't usually that long so potentially they were only contagious up to day 9. After that their immune system has usually wiped out the active virus.

Everyone is different but by the time people are in the hospital on respirators they're usually suffering from the follow on effects of either direct viral damage or their own immune system going nuts.

So why don't they put covid patients on a bucket of immunosuppressants after day 9?

They say yes.

I don't get this - if you're symptomatic beyond day 9, how can you not be contagious? A dry cough, for example, should be caused by the virus still being alive in the upper respiratory tract, i.e. you still should be able to infect others. Did they test aerosols, too?

What you feel as symptoms are your immune responses, you can not "feel" the actual virus. The immune reponse should go on for longer than the virus is functional.

Also, there has to be above a certain viral load to be contagious. I am however far from qualified to even guess what the thresholds are and I would think that it is mostly a matter of definition.

Are also the loss of smell and messed up taste effects of the immune system? I caught Covid at the end of October, and those symptoms lasted well beyond the final negative molecular swab test, so it seems the case.

Coughing is a taxing activity - it wastes energy, and causes discomfort. We cough for a reason - I doubt it's from the solidarity to infect others. Of course we can sense the virus, but the irritation it causes. Do all viruses, which replicate in the nasopharyngeal tract, trigger coughs? Maybe some viruses evolve to cause irritation similar to air passage obstruction, which triggers the instrict to clear your throat up?

Our bodies are not perfect or omniscient. We cough because it is evolutionarilly favored as a way to dislodge irritants, and viruses are evolutionarily favored to cause that coughing response strongly in order to spread. Coughing too long seems like a very possible consequence of those.

Live virus doesn't really cause symptoms as such, although they evolve to take advantage of it. The virus is basically re-purposing then melting a bunch of cells. The body's immune response is killing the viral structures and turning whole areas into the cellular equivalent of a battleground, killing off anything that is or is likely to be controlled by the virus.

Many of the worst symptoms aren't related to the presence or absence of the virus itself. If someone is turning blue from lack of oxygen, it isn't that the virus is doing anything here and now. It is that their lungs are non-functional from damage that the virus already did (note: past tense). You could remove every trace of active coronavirus from them and while they'd probably not get worse they also wouldn't get better very quickly. New lungs don't grow overnight.

This is not true. Viruses can directly kill the cells, by interfering with biological processes, necessary for cellular survival.

The clarification is helpful, but everything said was in fact true. Omitting this clarification doesn't negate everything else they said.

What the poster said above is incorrect. Covid does produce damage directly to the lung and neural cells, which especially evident as loss of smell and taste. The severe, deadly reaction is indeed of the immune system.

That's what I saw in many explainer videos, too.

The irritation still persists from the damaged tissue after the virus is eliminated. It takes time to rebuild.

So, senescent cells are just left for days to build up damage? We have mechanisms to clear up dead cells, many of them which actually killed themselves via apoptosis and were not directly killed by the virus.

PCR tests for RNA fragments. After 9 days it's likely you are surveying the battle field remains not actual live virus.

Naive guess: the damage was already done. Cough is a response to the damage caused by the virus, not to the virus itself.

If you get shot, you still have a bullet wound when the bullet comes out.

Damaged cells are cleaned up pretty fast. Of course, it's the virus causing damage, but we cough for the purpose to clear up the passages. In addition, the respiratory viruses probably trigger the cough as a vehicle to spread to other people.

> A dry cough, for example, should be caused by the virus still being alive in the upper respiratory tract

Why? I thought the body’s (potentially delayed) reaction caused the cough, not the virus

We have the instinct to cough to clear our air passages even without pathogens in certain cases. The virus is triggering these thru some irritation in order to spread to other people.

Right, but whatever process causes the coughing could well outlive the virus itself

Bother to provide any proof?

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