Entering week two of keeping healthy kids home because of positive Covid cases (they are vaccinated but school does asymptomatic surveillance testing). Current positive one is in tears that she isn't sick (she isn't) and wants to go to school this week. I'm ready to browse Zillow in Plano at this point.
Pretty good article with respect to individual behavior, but it did not cover society-wide behavior as well. I am mostly disappointed to see no discussion of air circulation and filtration in public buildings. This is an area where we can reduce the need for masking indoors at minimal expense and inconvenience, as long as we do not "grandfather" existing facilities, at least not for long. This is also an area where some public support for air handling system upgrades would be appropriate.
The part I find most surprising about the opinion poll is that the share of people who are undecided about mask mandates is so tiny. Rationally, with so much conflicting data and confounding variables, one would expect a lot more people to be in the undecided camp than 4%.
For what it's worth, I am one of those 4%. While I definitely believe that masks, themselves, work, when the right kind of mask is worn properly, I believe the case for mask mandates is much less clear cut. Are the differences in case counts between areas with and without mask mandates really caused by the mask mandates, or is it other factors, such as increased COVID-consciousness of the population at large, irrespective of the mandates, or higher vaccination rates? How many of the people that wear masks in areas with mandates are wearing them properly, and how many would be masking up anyway, even without a mandate? And, of course, how much COVID does a mask mandate have to prevent for the mandate to become justifiable in the first place? Is 10% enough? 30%? 40%? The answers to none of these questions are particularly clear.
A really clear example of the relative effectiveness of mask mandates (pre-Omicron) comes from Colorado: Larimer County, CO, largest city = college town Fort Collins; and Weld County, CO, largest city = college town Greeley. The two counties are side by side with similar population distributions (old vs young, etc.). Larimer County had a mask mandate and Weld County did not (there was no state-wide mandate at that time). The rate of disease spread and hospitalizations was about 30% greater in Weld County. It is hard to say whether masking alone is the sole cause of the difference. Other studies have shown that when mask mandates are in place people change other behavior as well (i.e.: ordering takeout rather than dining in, etc.). Right now, with Omicron, the two counties are pretty similar in case rates but Weld County still has a larger case total overall than Larimer County.
When checking in for an airplane trip, one question I recall is something like, "Have you had close contact with someone with Covid in the last 5 days?"
I wonder how many people click "Yes" and cancel their flight?
Thanks for this clear round-up. One thing I would have liked to see discussed here is ventilation. We can't control people's behavior but we do have some control over indoor ventilation in many spaces, and this does seem to have a real effect on transmission. I'd love to know more about what I should be doing at home with guests (e.g., is it worth it to invest in a HEPA air filter system)?
Many commenters here seem animated by the resentment towards local covid-hawks / mask snobs. Do you all live in SF / NYC? Come and live in east tennessee! All your burdens will be lifted.
There's a big difference between whether masks 'work' in the technical sense of reducing exposure to the virus in individuals vs whether mask mandates 'work' in the sense that such a policy reduces caseload across the population. I think it's fairly clear the mandates aren't doing much more at this point. They may have been somewhat effective early on, but once we brought back bars and restaurants at full capacity, it really stopped making sense to me. The frustrating thing is the Left used to understand this distinction. Case in point, abstinence is extremely effective at preventing pregnancy and STDs, abstinence only sex ed is not. This was a common thing for liberals to point out during the GWB years.
I'm going to push back on the mask data you presented. The study you cited that showed >50% reduction was a meta analysis, but the underlying data range from biased to severely biased. One of the biggest sources of data for that analysis is an internet survey. A study like this would probably not have been published if it were not covid times and it had not come to the conclusion that masking is effective.
The best data we do have is the Bangladesh study. The cloth masks had no effect, and the surgical masks had about a 10% reduction that is barely significant. However, there are concerns that in this study, the people in the mask villages responded at a different rate compared to the people in the non-mask villages, so even the 10% reduction may be due to other factors. We're also still waiting for the result of one of the endpoints: a random sampling of antibodies, which is the outcome that would give us the most accurate assessment of the effectiveness of masks. The authors have argued that the intervention villages only increased masking by 30% over the non-mask villages, so that's a floor. They only measured complaince going into mosques and tea shops. It's great that they tried to measure compliance, but it's not clear whether they are representative of the situations where transmission occurs. In rich countries, people are most likely to get infected at home or at work. It's fantastic that someone did conduct a randomized trial and it's great that the authors made their raw data available for others to pick apart (this is actually how science is supposed to work). There is another randomized trial in Burkina Faso, which should report its results soon. It does not reflect well on the state of science today that it took so long to get a randomized trial.
The Danemask study found a non-significant 20% reduction in infection in people assigned to wear surgical masks. The small effect size combined with it not being significant means we can rule out large effects. We probably should have conducted a larger trial afterwards. Interestingly, it appear that the authors of the Danemask study had trouble getting it published, likely because it came to the "wrong" conclusions. The journal that published it accompanied it with an editorial that basically said "ignore this". The Cochrane library, which is probably one of the most important sources of biomedical information reviewed the evidence on masks and respiratory illnesses and found little to no effect https://www.cochrane.org/CD006207/ARI_do-physical-measures-such-hand-washing-or-wearing-masks-stop-or-slow-down-spread-respiratory-viruses . The Cato institute also published (https://www.cato.org/sites/cato.org/files/2021-11/working-paper-64.pdf ) a review on cloth masks (I'm assuming it was published by a think tank because no journal wanted to touch something like this) that found little to no evidence for their effectiveness.
We do have a number of observational studies showing a benefit, but these studies are subject to bias and it's hard to control for some confounding variables. You can try to control for confounding factors, but it's hard and it's pretty much impossible to control for confounding factors that you don't know about.
The best example of how observational evidence can mislead is the question of hormone replacement in women. The observational data found that hormone replacement in post-menopausal women lowered the rate of heart disease. The women's health initiative randomized women to HRT or no HRT. In women who started HRT after they went through menopause, combined HRT actually raised the risk of heart disease. The estrogen only HRT group did lower the risk of heart attacks, but it can cause uterine cancer, so it's only used in women who've had a hysterectomy. This is why so many scientists push for randomized studies.
Mechanistic studies are helpful mainly in demonstrating that an intervention is likely to be ineffecitve. This is especially so in mannequin studies. Mannequins don't move their faces. Humans do all the time. We also need to take into account whether we are measuring large droplets or aerosols. SARS-cov2 is transmitted primarily by aerosols so decreasing the number of large droplets someone is exposed to is unlikely to have much of an effect.
Anyway, I would say that for at least the past 6 months, the quiet scientific consensus has been that cloth and surgical masks have little to no effect (which explains why you have to work really hard to show mask mandates have an effect), but that a properly fitted N95 mask provides excellent protection. This means that we could have prevented many of the early infections in healthcare settings by having healthcare workers wear N95s instead of surgical masks. That's soemthing that a post-covid commission really should investigate: how it happened and why we did not move faster to get them N95s.
Fortunately, we have three highly effective vaccines currently approved and Novavax is on its way to approval. If the goal is to prevent human suffering, the most important thing is to encourage vaccination. And it's important to stress that vaccine is the most effective way to protect yourself. Back in September, a large survey found that about 2/3 of people who were unvaccinated were wearing masks https://osf.io/4cr7a/ . They were likely not getting vaccinated because they didn't trust the safety of vaccines and believed that their masks were protecting them. The former CDC director's claim that masks were more effective than vaccines probably reinforced this belief. Some of those people likely died of Covid and those were preventable deaths.
I think we would all benefit from recognizing that in general humans react very poorly to having their airways covered and "then we'll force them to" is probably not a very good strategy.
End of rant. It's been a tough pandemic for those of us from the infectious disease world.
As if written by the CDC itself. If only we can find the right group of erudite celebrities we can convince people. Isn't it time to move on to therapeutics.
The term social distancing has done a lot of walking here. When the term was coined by pandemic planners it meant reducing social interactions, in other words close schools and reduce how often you meet people at work or socially. It didn't actually mean physical distancing in the same room. That is also important based on how this virus spreads, but I think we need to stop combining the terms so we don't confuse people (probably too late I guess).
We are always learning lessons from the last war and I'm worried that during the next flu pandemic we will experience enormous pushback to closing schools, which will actually be the number one intervention we can take for any virus that isn't a coronavirus.
Yep, the misuse of the term is maddening. If you haven't read Michael Lewis's "The Premonition", which is a good read, the surprisingly-recent history of social distancing comes up.
FYI, that Wall street Journal masking data is bogus. it was widely mocked by experts when that article came out
Entering week two of keeping healthy kids home because of positive Covid cases (they are vaccinated but school does asymptomatic surveillance testing). Current positive one is in tears that she isn't sick (she isn't) and wants to go to school this week. I'm ready to browse Zillow in Plano at this point.
Pretty good article with respect to individual behavior, but it did not cover society-wide behavior as well. I am mostly disappointed to see no discussion of air circulation and filtration in public buildings. This is an area where we can reduce the need for masking indoors at minimal expense and inconvenience, as long as we do not "grandfather" existing facilities, at least not for long. This is also an area where some public support for air handling system upgrades would be appropriate.
South Korean mask mandates are not enforced indoors at all. It’s for show. The quarantines and contact tracing are for real though.
What does NPI mean in this case? National Provider Identification number?
Non-pharmaceutical intervention.
Thanks!
The part I find most surprising about the opinion poll is that the share of people who are undecided about mask mandates is so tiny. Rationally, with so much conflicting data and confounding variables, one would expect a lot more people to be in the undecided camp than 4%.
For what it's worth, I am one of those 4%. While I definitely believe that masks, themselves, work, when the right kind of mask is worn properly, I believe the case for mask mandates is much less clear cut. Are the differences in case counts between areas with and without mask mandates really caused by the mask mandates, or is it other factors, such as increased COVID-consciousness of the population at large, irrespective of the mandates, or higher vaccination rates? How many of the people that wear masks in areas with mandates are wearing them properly, and how many would be masking up anyway, even without a mandate? And, of course, how much COVID does a mask mandate have to prevent for the mandate to become justifiable in the first place? Is 10% enough? 30%? 40%? The answers to none of these questions are particularly clear.
A really clear example of the relative effectiveness of mask mandates (pre-Omicron) comes from Colorado: Larimer County, CO, largest city = college town Fort Collins; and Weld County, CO, largest city = college town Greeley. The two counties are side by side with similar population distributions (old vs young, etc.). Larimer County had a mask mandate and Weld County did not (there was no state-wide mandate at that time). The rate of disease spread and hospitalizations was about 30% greater in Weld County. It is hard to say whether masking alone is the sole cause of the difference. Other studies have shown that when mask mandates are in place people change other behavior as well (i.e.: ordering takeout rather than dining in, etc.). Right now, with Omicron, the two counties are pretty similar in case rates but Weld County still has a larger case total overall than Larimer County.
https://www.mayoclinic.org/coronavirus-covid-19/map/colorado
When checking in for an airplane trip, one question I recall is something like, "Have you had close contact with someone with Covid in the last 5 days?"
I wonder how many people click "Yes" and cancel their flight?
Thanks for this clear round-up. One thing I would have liked to see discussed here is ventilation. We can't control people's behavior but we do have some control over indoor ventilation in many spaces, and this does seem to have a real effect on transmission. I'd love to know more about what I should be doing at home with guests (e.g., is it worth it to invest in a HEPA air filter system)?
I think the HEPA is worth it even if covid disappeared tomorrow.
This was a good piece. Nice work, Milan
Taiwan continues its zero COVID strategy with effectiveness, it seems — for now.
Many commenters here seem animated by the resentment towards local covid-hawks / mask snobs. Do you all live in SF / NYC? Come and live in east tennessee! All your burdens will be lifted.
There's a big difference between whether masks 'work' in the technical sense of reducing exposure to the virus in individuals vs whether mask mandates 'work' in the sense that such a policy reduces caseload across the population. I think it's fairly clear the mandates aren't doing much more at this point. They may have been somewhat effective early on, but once we brought back bars and restaurants at full capacity, it really stopped making sense to me. The frustrating thing is the Left used to understand this distinction. Case in point, abstinence is extremely effective at preventing pregnancy and STDs, abstinence only sex ed is not. This was a common thing for liberals to point out during the GWB years.
I'm going to push back on the mask data you presented. The study you cited that showed >50% reduction was a meta analysis, but the underlying data range from biased to severely biased. One of the biggest sources of data for that analysis is an internet survey. A study like this would probably not have been published if it were not covid times and it had not come to the conclusion that masking is effective.
The best data we do have is the Bangladesh study. The cloth masks had no effect, and the surgical masks had about a 10% reduction that is barely significant. However, there are concerns that in this study, the people in the mask villages responded at a different rate compared to the people in the non-mask villages, so even the 10% reduction may be due to other factors. We're also still waiting for the result of one of the endpoints: a random sampling of antibodies, which is the outcome that would give us the most accurate assessment of the effectiveness of masks. The authors have argued that the intervention villages only increased masking by 30% over the non-mask villages, so that's a floor. They only measured complaince going into mosques and tea shops. It's great that they tried to measure compliance, but it's not clear whether they are representative of the situations where transmission occurs. In rich countries, people are most likely to get infected at home or at work. It's fantastic that someone did conduct a randomized trial and it's great that the authors made their raw data available for others to pick apart (this is actually how science is supposed to work). There is another randomized trial in Burkina Faso, which should report its results soon. It does not reflect well on the state of science today that it took so long to get a randomized trial.
The Danemask study found a non-significant 20% reduction in infection in people assigned to wear surgical masks. The small effect size combined with it not being significant means we can rule out large effects. We probably should have conducted a larger trial afterwards. Interestingly, it appear that the authors of the Danemask study had trouble getting it published, likely because it came to the "wrong" conclusions. The journal that published it accompanied it with an editorial that basically said "ignore this". The Cochrane library, which is probably one of the most important sources of biomedical information reviewed the evidence on masks and respiratory illnesses and found little to no effect https://www.cochrane.org/CD006207/ARI_do-physical-measures-such-hand-washing-or-wearing-masks-stop-or-slow-down-spread-respiratory-viruses . The Cato institute also published (https://www.cato.org/sites/cato.org/files/2021-11/working-paper-64.pdf ) a review on cloth masks (I'm assuming it was published by a think tank because no journal wanted to touch something like this) that found little to no evidence for their effectiveness.
We do have a number of observational studies showing a benefit, but these studies are subject to bias and it's hard to control for some confounding variables. You can try to control for confounding factors, but it's hard and it's pretty much impossible to control for confounding factors that you don't know about.
The best example of how observational evidence can mislead is the question of hormone replacement in women. The observational data found that hormone replacement in post-menopausal women lowered the rate of heart disease. The women's health initiative randomized women to HRT or no HRT. In women who started HRT after they went through menopause, combined HRT actually raised the risk of heart disease. The estrogen only HRT group did lower the risk of heart attacks, but it can cause uterine cancer, so it's only used in women who've had a hysterectomy. This is why so many scientists push for randomized studies.
Mechanistic studies are helpful mainly in demonstrating that an intervention is likely to be ineffecitve. This is especially so in mannequin studies. Mannequins don't move their faces. Humans do all the time. We also need to take into account whether we are measuring large droplets or aerosols. SARS-cov2 is transmitted primarily by aerosols so decreasing the number of large droplets someone is exposed to is unlikely to have much of an effect.
Anyway, I would say that for at least the past 6 months, the quiet scientific consensus has been that cloth and surgical masks have little to no effect (which explains why you have to work really hard to show mask mandates have an effect), but that a properly fitted N95 mask provides excellent protection. This means that we could have prevented many of the early infections in healthcare settings by having healthcare workers wear N95s instead of surgical masks. That's soemthing that a post-covid commission really should investigate: how it happened and why we did not move faster to get them N95s.
Fortunately, we have three highly effective vaccines currently approved and Novavax is on its way to approval. If the goal is to prevent human suffering, the most important thing is to encourage vaccination. And it's important to stress that vaccine is the most effective way to protect yourself. Back in September, a large survey found that about 2/3 of people who were unvaccinated were wearing masks https://osf.io/4cr7a/ . They were likely not getting vaccinated because they didn't trust the safety of vaccines and believed that their masks were protecting them. The former CDC director's claim that masks were more effective than vaccines probably reinforced this belief. Some of those people likely died of Covid and those were preventable deaths.
I think we would all benefit from recognizing that in general humans react very poorly to having their airways covered and "then we'll force them to" is probably not a very good strategy.
End of rant. It's been a tough pandemic for those of us from the infectious disease world.
As if written by the CDC itself. If only we can find the right group of erudite celebrities we can convince people. Isn't it time to move on to therapeutics.
The term social distancing has done a lot of walking here. When the term was coined by pandemic planners it meant reducing social interactions, in other words close schools and reduce how often you meet people at work or socially. It didn't actually mean physical distancing in the same room. That is also important based on how this virus spreads, but I think we need to stop combining the terms so we don't confuse people (probably too late I guess).
We are always learning lessons from the last war and I'm worried that during the next flu pandemic we will experience enormous pushback to closing schools, which will actually be the number one intervention we can take for any virus that isn't a coronavirus.
Yep, the misuse of the term is maddening. If you haven't read Michael Lewis's "The Premonition", which is a good read, the surprisingly-recent history of social distancing comes up.