4 ms·

Presumably both people in this noted illustration also touched the door handle, possibly the door itself, and any number of other surfaces while entering the bu

by donatj 6y ago

Presumably both people in this noted illustration also touched the door handle, possibly the door itself, and any number of other surfaces while entering the building? I feel like drawing the link exclusively to air flow is tenuous at best. Saying with any level certainty that they didn't contract it _elsewhere_ seems dishonest.

red0point 6y ago
Well this is clearly stated in the paper. * Only the visitors (cases A and C) sitting in the air flow path of case B were infected with COVID-19, while other visitors (V2, V3) closer to the infector for a longer period of time but in the absence of direct air flow did not become infected. In addition, the visitors sitting at tables with cases A and C (V1, V6, and V7) were not infected with COVID-19 because they faced away from the infector’s face. These findings strongly suggest that this outbreak occurred by droplet transmission exceeding a 2 m distance and excluded contact and fomite transmission. This transmission pattern is similar with the outbreak of a restaurant with air conditioning in Guangzhou, China.21 In this article, the authors concluded that the most likely transmission was done by droplet and also emphasized the direction of air flow.* Also they analyzed the RNA to confirm linkage.
- donatj 6y ago
  That quote does nothing to disprove surface based infection though. Some people are better at not touching their faces than others.
  - red0point 6y ago
    True, however it makes sense if you look at the figure they provide, which shows airflow and infections: https://jkms.org/ViewImage.php?Type=F&aid=694440&id=F3&afn=63_JKMS_35_46_e415&fn=jkms-35-e415-g003_0063JKMS https://jkms.org/ViewImage.php?Type=F&aid=694440&id=F3&afn=6... If it were contact based, this would mean that at least one other in the restaurant must have contracted it that was outside of the airflow path. Since this not the case, the most likely thing is that transmission was with the airflow. Why is it that you are so certain about this being surface based transmission?
- zaroth 6y ago
  This lines up with other studies I’ve seen which show that contact and fomite transmission do not significantly drive transmission (that means hand washing and surface disinfecting won’t make much difference). Why would indoor dining be “safe”? Indoor anything is “unsafe”, as aerosolized transmission has been proven. Anything under a properly worn N95 doesn’t stop aerosols, and if anything will promote aerosols. The idea that wearing a mask from the time you walk in the door to the time you sit down is somehow affecting outcomes is insane. People should know that walking into a restaurant carries some risk of infection and a mask isn’t going to change that. 1. https://www.acpjournals.org/doi/full/10.7326/M20-5008 https://www.acpjournals.org/doi/full/10.7326/M20-5008
  - red0point 6y ago
    Do you have evidence to back up your claim that properly worn EN14683 IIR masks are not sufficient?
    - zaroth 6y ago
      How about because it says so on the label? > Type I, I R, II and II R face masks are medical masks tested in the direction of exhalation (inside to outside) and take into account the efficiency of bacterial filtration. Surgical masks of this type stop the wearer from infecting the surrounding environment. They are not effective at protecting the wearer from airbourne diseases such as coronavirus. > Type IIR face masks EN14683 are medical face masks made up of a 4 ply construction that prevents large particles from reaching the patient or working surfaces. Type IIR Face masks include a splash resistant layer to protect against blood and other bodily fluids. Type IIR face masks are tested in the direction of exhalation (inside to outside) and take into account the efficiency of bacterial filtration. They are not designed or tested to stop inhaling large droplets, nor exhaling small droplets. There is no scientific evidence they prevent the transmission of COVID and they specifically disclaim as much. However, properly worn FFP2, FFP3, N95 and other respirator masks are effective at protecting the wearer from viral transmission. That’s just not what most people are wearing outside a health care environment. And you can’t simply take them off when you sit down. First hit on Google: 1. https://www.dental-nursing.co.uk/news/covid-19-a-guide-to-face-masks https://www.dental-nursing.co.uk/news/covid-19-a-guide-to-fa...
djent 6y ago
Look at the time of arrival/departure for the customers. Case A arrived before Case B and Case A left before Case B left. On both sides of the door (or any other surface), Case A would have touched it before Case B. Despite this, Case B spread it to Case A.
- donatj 6y ago
  Is there evidence though that asymptomatic Case C didn't leave before A and B arrived and gave it to both via a surface?
  - cfmcdonald 6y ago
    Yes, they tested everyone else in the restaurant and no one else was infected. If you are going to make specific critiques like this, you really need to read the article first.

by donatj 6y ago

red0point 6y ago

Well this is clearly stated in the paper. * Only the visitors (cases A and C) sitting in the air flow path of case B were infected with COVID-19, while other visitors (V2, V3) closer to the infector for a longer period of time but in the absence of direct air flow did not become infected. In addition, the visitors sitting at tables with cases A and C (V1, V6, and V7) were not infected with COVID-19 because they faced away from the infector’s face. These findings strongly suggest that this outbreak occurred by droplet transmission exceeding a 2 m distance and excluded contact and fomite transmission. This transmission pattern is similar with the outbreak of a restaurant with air conditioning in Guangzhou, China.21 In this article, the authors concluded that the most likely transmission was done by droplet and also emphasized the direction of air flow.* Also they analyzed the RNA to confirm linkage.

donatj 6y ago
That quote does nothing to disprove surface based infection though. Some people are better at not touching their faces than others.
- red0point 6y ago
  True, however it makes sense if you look at the figure they provide, which shows airflow and infections: https://jkms.org/ViewImage.php?Type=F&aid=694440&id=F3&afn=63_JKMS_35_46_e415&fn=jkms-35-e415-g003_0063JKMS https://jkms.org/ViewImage.php?Type=F&aid=694440&id=F3&afn=6... If it were contact based, this would mean that at least one other in the restaurant must have contracted it that was outside of the airflow path. Since this not the case, the most likely thing is that transmission was with the airflow. Why is it that you are so certain about this being surface based transmission?
zaroth 6y ago
This lines up with other studies I’ve seen which show that contact and fomite transmission do not significantly drive transmission (that means hand washing and surface disinfecting won’t make much difference). Why would indoor dining be “safe”? Indoor anything is “unsafe”, as aerosolized transmission has been proven. Anything under a properly worn N95 doesn’t stop aerosols, and if anything will promote aerosols. The idea that wearing a mask from the time you walk in the door to the time you sit down is somehow affecting outcomes is insane. People should know that walking into a restaurant carries some risk of infection and a mask isn’t going to change that. 1. https://www.acpjournals.org/doi/full/10.7326/M20-5008 https://www.acpjournals.org/doi/full/10.7326/M20-5008
- red0point 6y ago
  Do you have evidence to back up your claim that properly worn EN14683 IIR masks are not sufficient?
  - zaroth 6y ago
    How about because it says so on the label? > Type I, I R, II and II R face masks are medical masks tested in the direction of exhalation (inside to outside) and take into account the efficiency of bacterial filtration. Surgical masks of this type stop the wearer from infecting the surrounding environment. They are not effective at protecting the wearer from airbourne diseases such as coronavirus. > Type IIR face masks EN14683 are medical face masks made up of a 4 ply construction that prevents large particles from reaching the patient or working surfaces. Type IIR Face masks include a splash resistant layer to protect against blood and other bodily fluids. Type IIR face masks are tested in the direction of exhalation (inside to outside) and take into account the efficiency of bacterial filtration. They are not designed or tested to stop inhaling large droplets, nor exhaling small droplets. There is no scientific evidence they prevent the transmission of COVID and they specifically disclaim as much. However, properly worn FFP2, FFP3, N95 and other respirator masks are effective at protecting the wearer from viral transmission. That’s just not what most people are wearing outside a health care environment. And you can’t simply take them off when you sit down. First hit on Google: 1. https://www.dental-nursing.co.uk/news/covid-19-a-guide-to-face-masks https://www.dental-nursing.co.uk/news/covid-19-a-guide-to-fa...

djent 6y ago

Look at the time of arrival/departure for the customers. Case A arrived before Case B and Case A left before Case B left. On both sides of the door (or any other surface), Case A would have touched it before Case B. Despite this, Case B spread it to Case A.

donatj 6y ago
Is there evidence though that asymptomatic Case C didn't leave before A and B arrived and gave it to both via a surface?
- cfmcdonald 6y ago
  Yes, they tested everyone else in the restaurant and no one else was infected. If you are going to make specific critiques like this, you really need to read the article first.