13 ms·

Covid patients breathe out large amounts of virus early on

89 points by belltaco 3y ago

francisofascii 3y ago
> COVID patients exhale high numbers of virus during the first eight days after symptoms start...then drop steeply." Eek. Eight days is longer than I expected.
- steve1977 3y ago
  Here in Switzerland you’re considered infectious 10 days after symptoms start (for mild cases)
  - eitally 3y ago
    That's what it used to be in the US, too, but it was reduced to 5 days about a year ago (which dramatically reduced school truancy, whether covid positive kids were still sick or not).
- GloriousKoji 3y ago
  Seems like the CDC reducing the suggested isolation time from 10 days to 5 was a mistake.
  - bugglebeetle 3y ago
    Not when the intent behind the decision was to keep people at work, consequences be damned.
    - JambalayaJim 3y ago
      Yes, it was only a mistake if you consider that control of the spread of the virus was of utmost importance. The real mistake was letting controlling spread take precedence over literally everything.
      - deleted 3y ago
        [deleted]
  - in_cahoots 3y ago
    My family (2 adults, 2 kids) was all vaccinated and the adults boosted when we got Covid for the first time. We all tested positive for 7+ days, and the baby was positive on Day 10 via a PCR test. Just one data point but 5 days has never seemed like long enough to me.
    - Scoundreller 3y ago
      I kinda wonder if the test is really good at catching more sinus-nasal infections and not so much lung-driven infections where there’s a lot more surface area to shed virus from. Or am I to assume if you’re infected, it’s caked along the entire respiratory tract.
    - myko 3y ago
      You can test positive after no longer being contagious: https://www.health.com/condition/infectious-diseases/coronavirus/how-long-can-you-test-positive-for-covid-19 https://www.health.com/condition/infectious-diseases/coronav... "You may test positive for as long as three months after having COVID-19" That said, yes 10 days seems much safer as a rule!
  - belltaco 3y ago
    That happened when Omicron initially hit the US and there were millions of cases a day during the 2021 holiday season. Airlines were running out of staff to run flights. It always felt more of a convenience decision than a medical one.
xnx 3y ago
I'm surprised this is news after 3+ years. I would've figured this would've been one of the first things to figure out. I'm sure many would've volunteered to be infected and closely studied early on to collect this information.
- histriosum 3y ago
  Intentionally infecting people for study isn't something that really fits with our medical ethics, at least as I understand them.
  - ch4s3 3y ago
    IIRC it can be done when there is little risk of serious adverse effects, or there is a known treatment that works well and mitigates risk of adverse effects.
  - Retric 3y ago
    It’s common practice for diseases where healthy people are unlikely to have severe issues, even if they may be deadly for some segment of the population. https://youtu.be/1v8u3ua6BPk?si=lzAQcZlmnBc1xvj1 https://youtu.be/1v8u3ua6BPk?si=lzAQcZlmnBc1xvj1
  - xnx 3y ago
    It can be controversial, but is done: https://en.wikipedia.org/wiki/Human_challenge_study https://en.wikipedia.org/wiki/Human_challenge_study
  - nradov 3y ago
    Imperial College London conducted a COVID-19 human challenge clinical trial. The risk to healthy subjects without comorbid conditions is extremely low. https://www.imperial.ac.uk/infectious-disease/research/human-challenge/ https://www.imperial.ac.uk/infectious-disease/research/human...
  - BurningFrog 3y ago
    Yeah, the medical "ethics" field is full of really weird and damaging decisions. Someone needs to do the work exposing what the hell is going on there.
mcpackieh 3y ago
I know a guy who still wears a half-face respirator every time he's in public even for just a second. I think at this rate he'll be wearing it for the rest of his life, unable to accept a new level of risk and move on with his life. I'd like to help him but I see no possible way, he's convinced that I and 99% of the rest of the public are suicidally insane like people who play literal russian roulette.
- thesaintlives 3y ago
  [flagged]
  - wait_what 3y ago
    [flagged]
- babblingdweeb 3y ago
  This is an odd hot-take for an active globally invasive and life altering virus. That person has assessed their risk level and determined that their community's disregard for their personal risk, negatively impacts their personal model. Therefore they have to use a different device to mitigate their risk. Seems pretty logical, matches with known science, with a minor exception that the half face respirator may not offer greater protection vs a well fitting* N95/KN95 * well-fitting being the crucial note there.
- steve1977 3y ago
  What if he’s right?
  - dingnuts 3y ago
    when almost everyone has already had the disease and was able to observe what it did to them -- which is the state we're at -- it's pretty hard to say that everyone needs to protect themselves. I know what COVID will do to me, because I had it already. He's not right. I was vaccinated, and the vaccine didn't work (it didn't prevent me from getting ill, get out of here with the 'better outcomes' bullshit, I'm healthy and COVID was still a flu-like illness for me, and I'm convinced the vaccine I was promised was 'safe and effective' did little or nothing) and masks didn't matter. It's like asking why we don't go around with masks on 24/7/365 to protect ourselves from the flu. Well, I've had the flu, and it's unpleasant, but it isn't worth the many downsides of proper N95 masking, and anything less than proper N95 masking is pointless. Most of the people I see wearing masks in public now are wearing completely ineffective cloth masks and a large number of them STILL wear them under their noses. These people are not thinking critically or looking at data. They're still just trapped in the media fear cycle from 2020.
kazinator 3y ago
"People coming out of a pool drip a lot of water early on. While that may seem obvious, did you know that the water is wet?" Infected people shed viruses. Someone with the common cold can be contagious for up to two weeks.
- thesaintlives 3y ago
  Go figure..
dekhn 3y ago
This PR purports to answer a question I had since the beginning of the epidemic when it was clear that transmission was through-air. """“For example, if we assume the infectious dose for COVID is 300 copies, then a person who is exhaling 1,000 viral copies per minute would exhale an infectious dose in 20 seconds (highly risky in an elevator), whereas a person who is exhaling two viral copies per minute would exhale an infectious dose in about two hours (probably safe in an elevator),” Lane said. """
- CoastalCoder 3y ago
  Can someone clarify the concept of "infectious dose"? My layman's understanding is that even one virion can potentially infect someone. It's just that the odds of infection generally increase with the number of virions. (Modulo many other factors like where the virions reside, immune response, etc.) But the concept of "an infectious dose" sounds much more binary to me. EDIT:s/viron/virion/g
  - dekhn 3y ago
    I'm not speaking as an authortiative individual here, but likely it's defined probabilistically in that 50% of people given a dosage show signs of infection later. See more here: https://en.wikipedia.org/wiki/Minimal_infective_dose https://en.wikipedia.org/wiki/Minimal_infective_dose
    - at_a_remove 3y ago
      It would be nice to find some charts of what that would be for various virii.
  - rolph 3y ago
    not all virions are equal. the viral assembly process, and the RNA replication process is error prone. many copies, of the covid virion, are incapable of cell entry or reproductive infection, due to defects in manufacture.
- PaulKeeble 3y ago
SoftTalker 3y ago
I wonder how this compares to other respiratory viruses, such as various flu strains? Shedding a lot of virus early, before the immune system has had a chance to develop and mount an attack, seems like what one would expect. But not sure if all viruses are like this?
- palata 3y ago
  Disclaimer: that is not my domain, consider it may be all wrong. One big difference in my understanding is the symptoms. For SARS-1 and MERS, people get symptoms earlier on, so they can be quarantine earlier and infect fewer people. I would guess that parts of the symptoms are triggered when the immune system starts reacting, and hence maybe for those two, it would just happen earlier? > Shedding a lot of virus early, before the immune system has had a chance to develop and mount an attack, seems like what one would expect. But yeah, that's generally what I would expect too.
taeric 3y ago
"We further found that levels of exhaled viral RNA increased with self-rated symptom-severity, though individual variation was high." I was curious on how high the variation was, so checked that out. There is a fairly wide swing in measurements. Not clear what that means on things. Would love to see more conversation on that. Most concerning on this, though, is "Levels of exhaled viral RNA did not differ across age, sex, time of day, vaccination status or viral variant." I think the data was clear enough that the vaccines are worth getting. However, this seems to shatter any thoughts folks may have that they are safer to others when they are vaccinated? I know that was at least a hope? (Question as I am not sure that was correct.) I seem to remember a previous study that showed super spreaders exist out there. In that some individuals shed substantially more virus than others. In ways that we don't understand, yet.
- op00to 3y ago
  If you don’t get Covid because you got the vaccine, that’s a benefit to others.
  - omginternets 3y ago
    And if the vaccine makes you an asymptomatic carrier, that's a harm to others. I think it's more useful to start with the question of what is actually happening, and examine the consequences from there. Otherwise, we find ourselves arguing in favor of our priors, which helps no one.
    - mint2 3y ago
      This PR article doesn’t do a good job explaining but it seems the severity was treated as an independent variable and controlled for, so with that assumption the article actually does imply vaccinated individuals shed less - yes the same amount when controlled for severity - but the cases are less severe. Why I say that is because of the two paragraphs: “”“ Mild and moderately symptomatic patients with COVID still exhale large amounts of virus, though severely symptomatic cases exhale higher levels on average, the study reports. Vaccinated and unvaccinated patients exhale similar levels of virus over the course of infection, the research shows.””” Edit: the actual preprint states “ We further found that levels of exhaled viral RNA increased with self-rated symptom-severity” so some of these statements in the PR article and article aren’t all squaring together.
LastCovidWave 3y ago
cOvId is AiRbOrNe, isn't over, and never went away. It doesn't matter how fast its spreading, it continues to spread, be highly contagious, with unknown long term effects. It makes all spaces unsafe and we need to work to live without it. Take measures to stop the spread and protect yourself and others. Stop getting infected. 3.5+ years into this if you're not helping, you just choosing to prolong the pandemic.
disambiguation 3y ago
The concept of measuring "viral copies" in breath is pretty cool, seems like a brand new technique? I can see it being invaluable in studying respitory viruses going forward. The only shortcoming of this study is the lack of data points _prior_ to symptoms. One of the hotly contested points of hygiene policy during the pandemic was about how the virus spreads before symptoms show up. I'm unsure if there's a study that already settles this, but this new method seems like a sure fire way.

89 points by belltaco 3y ago

> COVID patients exhale high numbers of virus during the first eight days after symptoms start...then drop steeply." Eek. Eight days is longer than I expected.

steve1977 3y ago
Here in Switzerland you’re considered infectious 10 days after symptoms start (for mild cases)
- eitally 3y ago
  That's what it used to be in the US, too, but it was reduced to 5 days about a year ago (which dramatically reduced school truancy, whether covid positive kids were still sick or not).
GloriousKoji 3y ago
Seems like the CDC reducing the suggested isolation time from 10 days to 5 was a mistake.
- bugglebeetle 3y ago
  Not when the intent behind the decision was to keep people at work, consequences be damned.
  - JambalayaJim 3y ago
    Yes, it was only a mistake if you consider that control of the spread of the virus was of utmost importance. The real mistake was letting controlling spread take precedence over literally everything.
    - deleted 3y ago
      [deleted]
- in_cahoots 3y ago
  My family (2 adults, 2 kids) was all vaccinated and the adults boosted when we got Covid for the first time. We all tested positive for 7+ days, and the baby was positive on Day 10 via a PCR test. Just one data point but 5 days has never seemed like long enough to me.
  - Scoundreller 3y ago
    I kinda wonder if the test is really good at catching more sinus-nasal infections and not so much lung-driven infections where there’s a lot more surface area to shed virus from. Or am I to assume if you’re infected, it’s caked along the entire respiratory tract.
  - myko 3y ago
    You can test positive after no longer being contagious: https://www.health.com/condition/infectious-diseases/coronavirus/how-long-can-you-test-positive-for-covid-19 https://www.health.com/condition/infectious-diseases/coronav... "You may test positive for as long as three months after having COVID-19" That said, yes 10 days seems much safer as a rule!
- belltaco 3y ago
  That happened when Omicron initially hit the US and there were millions of cases a day during the 2021 holiday season. Airlines were running out of staff to run flights. It always felt more of a convenience decision than a medical one.

xnx 3y ago

I'm surprised this is news after 3+ years. I would've figured this would've been one of the first things to figure out. I'm sure many would've volunteered to be infected and closely studied early on to collect this information.

histriosum 3y ago
Intentionally infecting people for study isn't something that really fits with our medical ethics, at least as I understand them.
- ch4s3 3y ago
  IIRC it can be done when there is little risk of serious adverse effects, or there is a known treatment that works well and mitigates risk of adverse effects.
- Retric 3y ago
  It’s common practice for diseases where healthy people are unlikely to have severe issues, even if they may be deadly for some segment of the population. https://youtu.be/1v8u3ua6BPk?si=lzAQcZlmnBc1xvj1 https://youtu.be/1v8u3ua6BPk?si=lzAQcZlmnBc1xvj1
- xnx 3y ago
  It can be controversial, but is done: https://en.wikipedia.org/wiki/Human_challenge_study https://en.wikipedia.org/wiki/Human_challenge_study
- nradov 3y ago
  Imperial College London conducted a COVID-19 human challenge clinical trial. The risk to healthy subjects without comorbid conditions is extremely low. https://www.imperial.ac.uk/infectious-disease/research/human-challenge/ https://www.imperial.ac.uk/infectious-disease/research/human...
- BurningFrog 3y ago
  Yeah, the medical "ethics" field is full of really weird and damaging decisions. Someone needs to do the work exposing what the hell is going on there.

mcpackieh 3y ago

I know a guy who still wears a half-face respirator every time he's in public even for just a second. I think at this rate he'll be wearing it for the rest of his life, unable to accept a new level of risk and move on with his life. I'd like to help him but I see no possible way, he's convinced that I and 99% of the rest of the public are suicidally insane like people who play literal russian roulette.

thesaintlives 3y ago
[flagged]
- wait_what 3y ago
  [flagged]
babblingdweeb 3y ago
This is an odd hot-take for an active globally invasive and life altering virus. That person has assessed their risk level and determined that their community's disregard for their personal risk, negatively impacts their personal model. Therefore they have to use a different device to mitigate their risk. Seems pretty logical, matches with known science, with a minor exception that the half face respirator may not offer greater protection vs a well fitting* N95/KN95 * well-fitting being the crucial note there.
steve1977 3y ago
What if he’s right?
- dingnuts 3y ago
  when almost everyone has already had the disease and was able to observe what it did to them -- which is the state we're at -- it's pretty hard to say that everyone needs to protect themselves. I know what COVID will do to me, because I had it already. He's not right. I was vaccinated, and the vaccine didn't work (it didn't prevent me from getting ill, get out of here with the 'better outcomes' bullshit, I'm healthy and COVID was still a flu-like illness for me, and I'm convinced the vaccine I was promised was 'safe and effective' did little or nothing) and masks didn't matter. It's like asking why we don't go around with masks on 24/7/365 to protect ourselves from the flu. Well, I've had the flu, and it's unpleasant, but it isn't worth the many downsides of proper N95 masking, and anything less than proper N95 masking is pointless. Most of the people I see wearing masks in public now are wearing completely ineffective cloth masks and a large number of them STILL wear them under their noses. These people are not thinking critically or looking at data. They're still just trapped in the media fear cycle from 2020.

kazinator 3y ago

"People coming out of a pool drip a lot of water early on. While that may seem obvious, did you know that the water is wet?" Infected people shed viruses. Someone with the common cold can be contagious for up to two weeks.

thesaintlives 3y ago
Go figure..

dekhn 3y ago

This PR purports to answer a question I had since the beginning of the epidemic when it was clear that transmission was through-air. """“For example, if we assume the infectious dose for COVID is 300 copies, then a person who is exhaling 1,000 viral copies per minute would exhale an infectious dose in 20 seconds (highly risky in an elevator), whereas a person who is exhaling two viral copies per minute would exhale an infectious dose in about two hours (probably safe in an elevator),” Lane said. """

CoastalCoder 3y ago
Can someone clarify the concept of "infectious dose"? My layman's understanding is that even one virion can potentially infect someone. It's just that the odds of infection generally increase with the number of virions. (Modulo many other factors like where the virions reside, immune response, etc.) But the concept of "an infectious dose" sounds much more binary to me. EDIT:s/viron/virion/g
- dekhn 3y ago
  I'm not speaking as an authortiative individual here, but likely it's defined probabilistically in that 50% of people given a dosage show signs of infection later. See more here: https://en.wikipedia.org/wiki/Minimal_infective_dose https://en.wikipedia.org/wiki/Minimal_infective_dose
  - at_a_remove 3y ago
    It would be nice to find some charts of what that would be for various virii.
- rolph 3y ago
  not all virions are equal. the viral assembly process, and the RNA replication process is error prone. many copies, of the covid virion, are incapable of cell entry or reproductive infection, due to defects in manufacture.
PaulKeeble 3y ago

SoftTalker 3y ago

I wonder how this compares to other respiratory viruses, such as various flu strains? Shedding a lot of virus early, before the immune system has had a chance to develop and mount an attack, seems like what one would expect. But not sure if all viruses are like this?

palata 3y ago
Disclaimer: that is not my domain, consider it may be all wrong. One big difference in my understanding is the symptoms. For SARS-1 and MERS, people get symptoms earlier on, so they can be quarantine earlier and infect fewer people. I would guess that parts of the symptoms are triggered when the immune system starts reacting, and hence maybe for those two, it would just happen earlier? > Shedding a lot of virus early, before the immune system has had a chance to develop and mount an attack, seems like what one would expect. But yeah, that's generally what I would expect too.

taeric 3y ago

"We further found that levels of exhaled viral RNA increased with self-rated symptom-severity, though individual variation was high." I was curious on how high the variation was, so checked that out. There is a fairly wide swing in measurements. Not clear what that means on things. Would love to see more conversation on that. Most concerning on this, though, is "Levels of exhaled viral RNA did not differ across age, sex, time of day, vaccination status or viral variant." I think the data was clear enough that the vaccines are worth getting. However, this seems to shatter any thoughts folks may have that they are safer to others when they are vaccinated? I know that was at least a hope? (Question as I am not sure that was correct.) I seem to remember a previous study that showed super spreaders exist out there. In that some individuals shed substantially more virus than others. In ways that we don't understand, yet.

op00to 3y ago
If you don’t get Covid because you got the vaccine, that’s a benefit to others.
- omginternets 3y ago
  And if the vaccine makes you an asymptomatic carrier, that's a harm to others. I think it's more useful to start with the question of what is actually happening, and examine the consequences from there. Otherwise, we find ourselves arguing in favor of our priors, which helps no one.
  - mint2 3y ago
    This PR article doesn’t do a good job explaining but it seems the severity was treated as an independent variable and controlled for, so with that assumption the article actually does imply vaccinated individuals shed less - yes the same amount when controlled for severity - but the cases are less severe. Why I say that is because of the two paragraphs: “”“ Mild and moderately symptomatic patients with COVID still exhale large amounts of virus, though severely symptomatic cases exhale higher levels on average, the study reports. Vaccinated and unvaccinated patients exhale similar levels of virus over the course of infection, the research shows.””” Edit: the actual preprint states “ We further found that levels of exhaled viral RNA increased with self-rated symptom-severity” so some of these statements in the PR article and article aren’t all squaring together.

LastCovidWave 3y ago

cOvId is AiRbOrNe, isn't over, and never went away. It doesn't matter how fast its spreading, it continues to spread, be highly contagious, with unknown long term effects. It makes all spaces unsafe and we need to work to live without it. Take measures to stop the spread and protect yourself and others. Stop getting infected. 3.5+ years into this if you're not helping, you just choosing to prolong the pandemic.

disambiguation 3y ago

The concept of measuring "viral copies" in breath is pretty cool, seems like a brand new technique? I can see it being invaluable in studying respitory viruses going forward. The only shortcoming of this study is the lack of data points _prior_ to symptoms. One of the hotly contested points of hygiene policy during the pandemic was about how the virus spreads before symptoms show up. I'm unsure if there's a study that already settles this, but this new method seems like a sure fire way.