Maybe it is all about airflow and some about masks. In this context I would like to make the following comment : In the early days of the pandemic dental offices ( dentists and hygienists ) were named as very high risk professions in the famous NY Times article https://www.nytimes.com/interactive/2020/03/15/business/economy/coronavirus-worker-risk.html. More than 9 months into the pandemic this high risk has not shown to be true as per this recent study published in Journal of American Dental Association https://medicalxpress.com/news/2020-10-covid-dentists-percent.html. I think what may have largely mitigated this risk is use of adequate mask wear ( which was a 100% compliant practice amongst dental workers even before the pandemic unlike various other medical and allied professions) and the ubiquitous use of high vacuum evacuation systems chair side during typical dental procedures
Indeed. Dental offices are another excellent example of a dog that did not bark, showing us that infection control is possible. One caveat though: dental offices have trained personnel so they are adhering to masking protocols and have high quality masks.
In the April 2019 The Atlantic article you had presciently advocated for mask wear by general public. I wish this was adopted immediately countrywide. Clear and effective messaging by our media, health experts and government officials would have changed the course of this pandemic.
Hi Zeynep - Wanted to say that I'm a huge fan of your work since the pandemic started. I work for an air filtration company in the CA Bay Area and advise a lot of local hospitals on how to best protect against airborne spread. I wanted to know if the recent Insight article you had regarding the South Korea study talked about the effect of recirculated air. From what I can tell from the diagram, the area in question only had supply vents with no exhaust vent re-circulation present. Is that accurate or am I missing something?
Did the study mention the rating of the air filters present in these airhandlers if they were recirculating air? It doesn't appear the virus survived air recirculation if that's the case, something worth looking at for the customers I advise. Also curious as to the rate of air changes per hour they were getting in this space.
Looking over the study myself, it does state this was a poorly ventilated space that only had two ceiling type air conditioners. Curious if there's another similarly detailed study that has more precise data about the type of air conditioners / filters / flow rates present in the room. Appreciate all the help your articles have provided!
Curious as to if this could be applied to residence halls and college dining rooms, as most are scheduled to return to campus in January/February, and as it appears from tracing the deaths, in the Midwest, backward, the timing lines up with the colleges reopening, helping to elevate the trains of transmission (as 20k in people moved to 2-3 sq. miles). Wondering if we will see a replay of what happened, if ventilation issues haven't been/weren't addressed, and now with colder weather, more people indoors, less windows open, etc. I know we will have vaccines for the LTCFs, almost in tandem, which would stave off some of the deaths/hospitalizations, that we have been seeing, but wondering if more mitigation measures, with regard to colleges/universities would be appropriate.
Indeed. I think it's practically impossible to stop spread among a bunch of young people in congregate living situations. On the one hand, they tend not to suffer terrible consequences, on average compared to baseline risk—meningitis or flu outbreak in dorms etc. On the other hand, if they then go home, that's like a country-wide superspreading event. With colleges, I think if we bring them on campus, we have duty to keep them there.
In the same "small data" vein, there is a very clean study of transmission on a Chinese bus. Ye Shen et al, Community Outbreak Investigation of SARS-CoV-2 Transmission Among Bus Riders in Eastern China, JAMA Internal Medicine, doi:10.1001/jamainternmed.2020.5225
Fantastic writing, insights, and sleuthing as always - thanks! One question I had - sorry if I missed it in the article - was there detailed work done on people who did not get it beyond a simple PCA test? Antibody or more complex T Cell testing? Thanks again, I so want to go to see movies on a big screen.. seems like it can happen *ESP* if there are no refreshments and masks are required?
Not that I can see in the article. For this purposes though, PCR is more accurate than antibody testing (since they got to people quickly). On the movie theaters: I agree! I think once vaccinations start and hospitals are no longer so overloaded, movie theaters could plausibly be one of the quicker activities to return.
You make me excited to go to the cinema again! When I told my partner about your article, he said, “Good—another reason people should be quit during the movie.”
Reading your analysis makes me wonder if if it was mandated that in a movie theatre you would have to be sitting with your masks on all the time and there be no food consumption allowed, that would make it safe enough to allow for general use. This might help bring back so many jobs and give a safe way for families to get out of the house and still be safe. ....I wonder...?
Maybe this is not the time to encourage movie theaters, but I would not feel at very high risk in the scenario you described. I'd still avoid it because it's not essential, but it seems like one of the activities that could return relatively quickly with some safeguards.
Thanks for sharing this. It's an illuminating study. Given the impact the virus has had on our health and livelihoods, I do wish there were more analyses similar to this one, but of particular activities - especially as we contemplate shutting down some things that may not be spreading the virus at all. I wish someone could have gone back to B and followed him around eating outside and seeing what effect he might have had on people. That might help us determine whether shutting down outdoor dining as we're about to do in CA is worthwhile, especially since restaurants have gone to great expense to make it doable in winter.
It would be wonderful if this kind of information became more widely known. So much of the standard news that people receive is in such small, bite sized forms that our natural capacity to strain out gnats while gleefully swallowing camels at unmasked parties is helpful to this plucky little virus. Thank you for this thoughtful piece!
The B-to-A transmission looks a bit like an outlier -- I trust the authors of the study have done *some* due diligence about the possibility of the transmission chain being incorrectly reconstructed, but from what I understand there is a base level of uncertainty that just cannot be effaced with phylogenetics. Parallel evolution happens.
Alternatively, could B and A have met at the counter or at the entrance, with B paying or leaving and A waiting to be seated)
Ooh, nice, they did rule out meeting at the entrance or at the counter. Air conditioning seems to be the major culprit here, or at least a massive contributor.
This is fascinating, thank you!
Maybe it is all about airflow and some about masks. In this context I would like to make the following comment : In the early days of the pandemic dental offices ( dentists and hygienists ) were named as very high risk professions in the famous NY Times article https://www.nytimes.com/interactive/2020/03/15/business/economy/coronavirus-worker-risk.html. More than 9 months into the pandemic this high risk has not shown to be true as per this recent study published in Journal of American Dental Association https://medicalxpress.com/news/2020-10-covid-dentists-percent.html. I think what may have largely mitigated this risk is use of adequate mask wear ( which was a 100% compliant practice amongst dental workers even before the pandemic unlike various other medical and allied professions) and the ubiquitous use of high vacuum evacuation systems chair side during typical dental procedures
Indeed. Dental offices are another excellent example of a dog that did not bark, showing us that infection control is possible. One caveat though: dental offices have trained personnel so they are adhering to masking protocols and have high quality masks.
In the April 2019 The Atlantic article you had presciently advocated for mask wear by general public. I wish this was adopted immediately countrywide. Clear and effective messaging by our media, health experts and government officials would have changed the course of this pandemic.
This is some of the most important/interesting COVID info I've come across lately. Thanks so much for breaking it down Zeynep.
I'm glad you found it useful!
Hi Zeynep - Wanted to say that I'm a huge fan of your work since the pandemic started. I work for an air filtration company in the CA Bay Area and advise a lot of local hospitals on how to best protect against airborne spread. I wanted to know if the recent Insight article you had regarding the South Korea study talked about the effect of recirculated air. From what I can tell from the diagram, the area in question only had supply vents with no exhaust vent re-circulation present. Is that accurate or am I missing something?
Did the study mention the rating of the air filters present in these airhandlers if they were recirculating air? It doesn't appear the virus survived air recirculation if that's the case, something worth looking at for the customers I advise. Also curious as to the rate of air changes per hour they were getting in this space.
I don't know details beyond the study itself, but the authors may have that information!
Looking over the study myself, it does state this was a poorly ventilated space that only had two ceiling type air conditioners. Curious if there's another similarly detailed study that has more precise data about the type of air conditioners / filters / flow rates present in the room. Appreciate all the help your articles have provided!
Curious as to if this could be applied to residence halls and college dining rooms, as most are scheduled to return to campus in January/February, and as it appears from tracing the deaths, in the Midwest, backward, the timing lines up with the colleges reopening, helping to elevate the trains of transmission (as 20k in people moved to 2-3 sq. miles). Wondering if we will see a replay of what happened, if ventilation issues haven't been/weren't addressed, and now with colder weather, more people indoors, less windows open, etc. I know we will have vaccines for the LTCFs, almost in tandem, which would stave off some of the deaths/hospitalizations, that we have been seeing, but wondering if more mitigation measures, with regard to colleges/universities would be appropriate.
Indeed. I think it's practically impossible to stop spread among a bunch of young people in congregate living situations. On the one hand, they tend not to suffer terrible consequences, on average compared to baseline risk—meningitis or flu outbreak in dorms etc. On the other hand, if they then go home, that's like a country-wide superspreading event. With colleges, I think if we bring them on campus, we have duty to keep them there.
In the same "small data" vein, there is a very clean study of transmission on a Chinese bus. Ye Shen et al, Community Outbreak Investigation of SARS-CoV-2 Transmission Among Bus Riders in Eastern China, JAMA Internal Medicine, doi:10.1001/jamainternmed.2020.5225
Yes, that's another excellent study!
Fantastic writing, insights, and sleuthing as always - thanks! One question I had - sorry if I missed it in the article - was there detailed work done on people who did not get it beyond a simple PCA test? Antibody or more complex T Cell testing? Thanks again, I so want to go to see movies on a big screen.. seems like it can happen *ESP* if there are no refreshments and masks are required?
Not that I can see in the article. For this purposes though, PCR is more accurate than antibody testing (since they got to people quickly). On the movie theaters: I agree! I think once vaccinations start and hospitals are no longer so overloaded, movie theaters could plausibly be one of the quicker activities to return.
You make me excited to go to the cinema again! When I told my partner about your article, he said, “Good—another reason people should be quit during the movie.”
Hah! I'm not rushing back myself but I think we will find that the quiet and masked activities are safer than we thought!
Reading your analysis makes me wonder if if it was mandated that in a movie theatre you would have to be sitting with your masks on all the time and there be no food consumption allowed, that would make it safe enough to allow for general use. This might help bring back so many jobs and give a safe way for families to get out of the house and still be safe. ....I wonder...?
Maybe this is not the time to encourage movie theaters, but I would not feel at very high risk in the scenario you described. I'd still avoid it because it's not essential, but it seems like one of the activities that could return relatively quickly with some safeguards.
Thanks for sharing this. It's an illuminating study. Given the impact the virus has had on our health and livelihoods, I do wish there were more analyses similar to this one, but of particular activities - especially as we contemplate shutting down some things that may not be spreading the virus at all. I wish someone could have gone back to B and followed him around eating outside and seeing what effect he might have had on people. That might help us determine whether shutting down outdoor dining as we're about to do in CA is worthwhile, especially since restaurants have gone to great expense to make it doable in winter.
Thank you! This kind of going deep can help us figure out not just what's riskier, but also what we can feel more comfortable and how.
It would be wonderful if this kind of information became more widely known. So much of the standard news that people receive is in such small, bite sized forms that our natural capacity to strain out gnats while gleefully swallowing camels at unmasked parties is helpful to this plucky little virus. Thank you for this thoughtful piece!
Thank you!
The B-to-A transmission looks a bit like an outlier -- I trust the authors of the study have done *some* due diligence about the possibility of the transmission chain being incorrectly reconstructed, but from what I understand there is a base level of uncertainty that just cannot be effaced with phylogenetics. Parallel evolution happens.
Alternatively, could B and A have met at the counter or at the entrance, with B paying or leaving and A waiting to be seated)
They do have CCTV footage which they watched to rule all those out. If you read the study, they really went to great lengths.
Ooh, nice, they did rule out meeting at the entrance or at the counter. Air conditioning seems to be the major culprit here, or at least a massive contributor.