Enough with the masks already
There's something from the scientific studies about masks that everyone is studiously not talking about. But the alpacas know.
Over at the Palo Verde Alpaca Ranch and Nuclear Generating Station, the nuclear part of the business has been going well, but the alpaca wool part is not. It turns out the market for fully-irradiated alpaca wool (which, after consultation with Elon Musk, they decided to call HyperWool) isn’t so great, and the investors are not happy.
Elon and the alpacas have a solution: HyperMasks. If humans are going to put cloths on their faces (and be self-righteous about it), alpacas should be able to make a few bucks from this silliness. And Elon is the world’s greatest expert at monetizing moral superiority.
To prepare their marketing campaign, the alpacas did some research into the benefits and risks of their new cash cow (or cash alpaca).
Randomized controlled trials - you know, the way we normally evaluate medical interventions
The alpacas didn’t just do their own searching, they also cataloged all the studies referenced in literature reviews, and government and NGO reports on masks - these studies represent the sum total of what everyone found and referenced.
In total they found 18 randomized controlled trials (RCTs) involving masks published between 2008 and 2019, which is 18 more than Todd the CDC Intern managed to find when he compiled the CDC web page about masks
Alpacas, like the staff at the CDC, need to spell out the big words but they managed to digest (!) the whole list.
However, 18 is a lot to cover in a single Substack post. So they provided us a quick summary of each one - references and links are at the end, and 16 of the 18 are free to download. Apparently “free” is outside the CDC’s budgetary constraints so the alpacas are picking up the slack by copy-pasting the URLs for them.
So what were the outcomes of these studies, if we want to know the difference between people wearing masks and people not wearing masks? Let’s get on with that crazy thing we do here - reading the scientific papers.
(1) Preliminary findings of a randomized trial of non-pharmaceutical interventions to prevent influenza transmission in households (Cowling et al. 20081)
This first one was funded by the CDC - who can fund studies, but can’t be bothered to read them.
The laboratory-based or clinical secondary attack ratios did not significantly differ across the intervention arms.
So no benefit to masks. One down, 17 to go.
(2) Facemasks and hand hygiene to prevent influenza transmission in households: a cluster randomized trial (Cowling et al. 20092)
This is the larger study based on the previous study, and was also funded by the CDC. Again no benefit to masks (the differences were not statistically significant).
Hand hygiene with or without facemasks seemed to reduce influenza transmission, but the differences compared with the control group were not significant.
Let’s keep score: 2 no difference, 0 positive, 0 negative.
The alpacas want to know how they can get some of that sweet, sweet CDC cash - It looks like they can just copy pages from the phone book since the CDC clearly doesn’t read the results of these studies anyway.
(3) Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: a randomized controlled trial (Jacobs et al. 20093)
Face mask use in health care workers has not been demonstrated to provide benefit in terms of cold symptoms or getting colds. A larger study is needed to definitively establish noninferiority of no mask use.
Another big donut: 3 no difference, 0 positive, 0 negative.
(4) Surgical mask vs N95 respirator for preventing influenza among health care workers: a randomized trial (Loeb et al. 20094)
This is called a noninferiority trial - was one intervention worse than the other? No. And there was no unmasked control, so the lack of difference between the two types of masks could just mean they did nothing.
Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza.
3 no difference, 0 positive, 0 negative, 1 no unmasked control.
(5) Face mask use and control of respiratory virus transmission in households (MacIntyre et al. 20095)
The key findings are that <50% of participants were adherent with mask use and that the intention-to-treat analysis showed no difference between arms.
So no benefit again. Less than 50% adherent? No big deal. Alpacas, like the pharma companies, don’t care if you use the product (or if it works), they just care about getting paid.
4 no difference, 0 positive, 0 negative, 1 no control.
(6) Mask use, hand hygiene, and seasonal influenza-like illness among young adults: a randomized intervention trial (Aiello et al. 20106)
Something finally happened! The alpacas are stampeding in joy.
We observed significant reductions in ILI during weeks 4–6 in the mask and hand hygiene group, compared with the control group, ranging from 35% (confidence interval [CI], 9%–53%) to 51% (CI, 13%–73%), after adjusting for vaccination and other covariates. Face mask use alone showed a similar reduction in ILI compared with the control group, but adjusted estimates were not statistically significant. Neither face mask use and hand hygiene nor face mask use alone was associated with a significant reduction in the rate of ILI cumulatively.
Wait a second… over the whole study (cumulatively) there was no significant benefit. But if we look at a specific subset of the time period, mask+hand hygiene resulted in a reduction in infections.
Note: “Not statistically significant” is science talk for “the result could be due to chance.” Alpacas are notorious gambling addicts so they’re familiar with the vagaries of lady chance.
These findings suggest that face masks and hand hygiene may reduce respiratory illnesses in shared living settings and mitigate the impact of the influenza A(H1N1) pandemic.
Not exactly strong language. (“Findings suggest… may reduce…”) But for the whole study, as designed - no benefit. This is “no benefit” based on the design of the study, but we’re going to add a new category to try and capture the fact that there might be something positive here.
4 No difference, 0 positive, 0 negative, 1 may help, 1 no control.
(7) Surgical mask to prevent influenza transmission in households: a cluster randomized trial (Canini et al. 20107)
In various sensitivity analyses, we did not identify any trend in the results suggesting effectiveness of facemasks.
5 No difference, 0 positive, 0 negative, 1 may help, 1 no control.
(8) Use of face masks by non-scrubbed operating room staff: a randomized controlled trial (Webster et al. 20108)
Does everyone in the operating room need to wear a mask? This isn’t as relevant to community mask wearing, but we don’t have a lot of studies anyway.
Surgical site infection rates did not increase when non-scrubbed operating room personnel did not wear a face mask.
This should be taken as good news - if you’re short on masks, don’t put them on the non-scrubbed staff because they don’t do any good.
6 No difference, 0 positive, 0 negative, 1 may help, 1 no control.
(9) Impact of non-pharmaceutical interventions on URIs and influenza in crowded, urban households (Larson et al. 20109)
In this population, there was no detectable additional benefit of hand sanitizer or face masks over targeted education on overall rates of URIs, but mask wearing was associated with reduced secondary transmission and should be encouraged during outbreak situations.
However, the relatively small number of individuals studied to date has not been adequate to provide an estimate of effect size and, overall, there were no differences in infection rates among the intervention groups.
So again, no statistically significant difference. But at least the authors are upbeat about it. “Associated with” means they couldn’t prove a cause and effect relationship.
7 No difference, 0 positive, 0 negative, 1 may help, 1 no control.
(10) Pilot randomised controlled trial to test effectiveness of facemasks in preventing influenza-like illness transmission among Australian Hajj pilgrims in 2011 (Barasheed et al. 201110)
However, laboratory results did not show any difference between the two groups. This pilot study shows that a large trial to assess the effectiveness of facemasks use at Hajj is feasible.
8 No difference, 0 positive, 0 negative, 1 may help, 1 no control.
(11) A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care worker (MacIntyre et al. 201111)
The rates of all outcomes were higher in the convenience no-mask group than in the masks groups. By adjusted intention-to-treat analysis, N95 respirators but not medical masks had significantly lower rates of infection compared to no masks. However, the convenience no-mask group was not a randomized control arm and hospitals in this group were actually selected on the basis that most of their staff did not wear masks (which is not the norm in hospitals in Beijing), suggesting that conditions in those hospitals were different than those in hospitals from the masks groups. As a consequence, it is not possible to make any definitive judgement on the efficacy of masks on this basis.
The no-mask group was not a randomized control arm, so the authors say we can’t draw definitive conclusions. Other things might also be different in those hospitals compared to the masking groups. N95s were better than medical masks, but is this because they prevented infections, or because medical masks caused infections? There’s no way to know without a proper control.
8 No difference, 0 positive, 0 negative, 1 may help, 2 no control.
(12) Findings from a household randomized controlled trial of hand washing and face masks to reduce influenza transmission in Bangkok, Thailand (Simmerman et al. 201112)
The alpacas have pointed out that several studies actually combine masks and hand washing. Can’t someone get a positive result just with masks? They’re starting to get a little suspicious of the mask claims being made by the CDC.
Influenza transmission was not reduced by interventions to promote hand washing and face mask use.
This study is interesting because the researchers saw the opposite of what was expected. The calculated Odds Ratio for both lab confirmed flu and for a clinical diagnosis of flu were worse in the mask group. This was not statistically significant for the lab confirmed results, but it was significant for the clinical diagnosis of illness. That’s the opposite of good.
8 No difference, 0 positive, 1 negative, 1 may help, 2 no control.
(13) Facemasks, hand hygiene, and influenza among young adults: a randomized intervention trial (Aiello et al. 201213)
There were no substantial reductions in ILI or laboratory-confirmed influenza in the face mask only group compared to the control.
Like the previous Aiello study, if they look at a subset of the time period there appears to be a benefit, but not for the study as a whole. This time, the time period is the first few weeks of the study (in the previous Aiello study it was the last few weeks).
But by the end of the study there was no overall benefit. We’ll call this another “may help” for now, and discuss in more detail later.
8 No difference, 0 positive, 1 negative, 2 may help, 2 no control.
(14) The role of facemasks and hand hygiene in the prevention of influenza transmission in households: results from a cluster randomised trial (Suess et al. 201214)
Overall, differences in SAR were not significant, neither for laboratory confirmed secondary cases nor for ILI (Table 2), neither in primary analysis nor after stratification for season, influenza virus (sub)type or timing of the first household visit (Table 2).
9 No difference, 0 positive, 1 negative, 2 may help, 2 no control.
(15) A randomized clinical trial of three options for N95 respirators and medical masks in health workers (MacIntyre et al. 201315)
In a setting of high occupational risk for HCWs, the key observation of this study is significant protective efficacy against clinical infection of continuous use of N95 respirators compared with targeted use and medical masks, despite significantly poorer adherence in the continuous use N95 arm.
Again there is no control group of people without masks, which means we have no way of knowing if the N95s did better because they reduced infection, or the medical masks did worse because they increased infections.
9 No difference, 0 positive, 1 negative, 2 may help, 3 no control.
(16) Efficacy of face masks and respirators in preventing upper respiratory tract bacterial colonization and co-infection in hospital healthcare workers (MacIntyre et al. 201416)
N95 respirators were significantly protective against bacterial colonization, co-colonization and viral-bacterial co-infection. We showed that dual respiratory virus or bacterial-viral co-infections can be reduced
by the use of N95 respirators.
A convenience control group of 481 HCW who did not routinely wear masks
were recruited and prospectively followed up in the same way as the trial participants for the development of symptoms.
The control was a convenience sample, meaning those subjects were not randomly assigned to the unmasked group. They were just people who said they didn’t usually wear masks, but we don’t know if their jobs and behaviors were equivalent to the other groups.
This isn’t an RCT of masks vs. no masks so the authors don’t make firm claims comparing the them, but we’re going to put this one down as a “may help” due to the convenience sample.
9 No difference, 0 positive, 1 negative, 3 may help, 3 no control.
(17) A cluster randomised trial of cloth masks compared with medical masks in healthcare workers (MacIntyre et al. 201517)
We finally get a statistically significant result of a mask group vs. a no mask group. And that result? Cloth masks might be a little dangerous - the alpacas are all in a tizzy.
We have provided the first clinical efficacy data of cloth masks, which suggest HCWs should not use cloth masks as protection against respiratory infection. Cloth masks resulted in significantly higher rates of infection than medical masks, and also performed worse than the control arm.
So in this one the authors specifically say not to put cloth masks on health care workers. That’s a pretty strong negative.
9 No difference, 0 positive, 2 negative, 3 may help, 3 no control.
(18) N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial (Radonovich et al. 201918)
And finally, another trial with no unmasked control. This test was comparing N95s and medical masks.
In this pragmatic, cluster randomized clinical trial involving 2862 health care personnel, there was no significant difference in the incidence of laboratory-confirmed influenza among health care personnel with the use of N95 respirators (8.2%) vs medical masks (7.2%).
The N95s were no better than the medical masks, contradicting the findings from some of the MacIntyre studies.
9 No difference, 0 positive, 2 negative, 3 may help, 4 no control.
Since they clearly can’t read, someone please transmit this verbally to the staff at the CDC:
For the 18 studies, we have:
9 with no statistically significant benefit of masks
4 with no unmasked control
0 with a positive result vs. unmasked control
2 with a negative result vs. unmasked control
3 with “may help” vs. unmasked control (but not a statistically significant result)
Of the 14 studies with a “no mask” control, 9 showed no benefit, 3 showed weak evidence of benefit, and 2 showed strong evidence of harm.
Now, in the largest font Substack has available:
The evidence that masks can be harmful is at least as strong as the evidence they may help.
None of this justifies forcing anyone to do anything.
And now the dirty little secret no one talks about
A lot of studies look for lab confirmed influenza because it’s a common virus and people get infected with it every flu season. Some of the studies also use one or more clinical definitions of influenza, meaning they have doctors diagnose people for illness (a clinical diagnosis of the flu is usually defined as a mild fever plus one other symptom).
Let’s re-review some of the studies, looking at those clinical diagnoses.
Cowling 2008
The Odds Ratio (OR) for the mask group was higher (that’s bad) for lab confirmed influenza. The study used 3 different definitions of clinical illness. The OR was lower for clinical flu per definition 1, but higher for clinical flu per definitions 2 and 3.
Cowling 2009
The OR for lab confirmed influenza was lower, but for the clinical definition it was higher (and by a bigger margin).
MacIntyre 2009
In the intention-to-treat analysis, the surgical masks were slightly worse than no mask (Risk Ratio 1.29 and 1.33), and the P2 masks (like an N95) were very slightly better than no mask (RR 0.91 and 0.95).
Although not extremely strong, this is evidence that surgical masks make things worse.
Simmerman 2011
The Odds Ratio for the hand washing group and hand washing + face mask group were both worse than the control. For clinically diagnosed illness the result was statistically significant. Were the masks making people sick, just not with influenza virus?
Aiello 2010 & 2012
In the first study the Risk Ratios (RR) are about even at the start, but masks had a lower RR at the end. Overall, there was no statistically significant reduction. However, in the second study the RR for masks started lower but climbed every week until it was higher than no masks. The cumulative RR was higher for masks, but again not statistically significant.
Here is the point of this whole post
In several studies, the rate of diagnosed illness is higher in the mask group even though the lab confirmed influenza isn’t. These people aren’t faking it - they really have fevers and sore throats, it’s just not from influenza virus. And it’s often a statistically significant result.
But these studies are testing for lab confirmed influenza virus, so they don’t test for other things. The masks made these people sick but we don’t know why. Was it from other viruses? Bacteria? Fungi? Was it from breathing the chemicals in the masks? We don’t know, but we should be concerned.
Based on these studies, we have good reason to think that wearing masks all day will make more people sick.
And that’s the dirty little mask secret no one talks about.
A while back I wrote a ten-post series about the CDC’s web page on masks, looking at all their references as well as the studies they chose not to reference. If you want to read waaay to much about this subject, click here:
I also sprinkled in some useless commentary about a 90s sitcom to try and make it less boring. In hindsight I failed in that goal - this subject is boring no matter how it’s presented.
Cowling BJ, Fung RO, Cheng CK, et al. Preliminary findings of a randomized trial of non-pharmaceutical interventions to prevent influenza transmission in households. PLoS One. 2008;3(5):e2101. Published 2008 May 7. doi:10.1371/journal.pone.0002101
https://pubmed.ncbi.nlm.nih.gov/18461182/
Cowling BJ, Chan KH, Fang VJ, et al. Facemasks and hand hygiene to prevent influenza transmission in households: a cluster randomized trial. Ann Intern Med. 2009;151(7):437-446. doi:10.7326/0003-4819-151-7-200910060-00142
https://pubmed.ncbi.nlm.nih.gov/19652172/
Jacobs JL, Ohde S, Takahashi O, Tokuda Y, Omata F, Fukui T. Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: a randomized controlled trial. Am J Infect Control. 2009;37(5):417-419. doi:10.1016/j.ajic.2008.11.002
https://pubmed.ncbi.nlm.nih.gov/19216002/
Loeb M, Dafoe N, Mahony J, et al. Surgical mask vs N95 respirator for preventing influenza among health care workers: a randomized trial. JAMA. 2009;302(17):1865-1871. doi:10.1001/jama.2009.1466
https://pubmed.ncbi.nlm.nih.gov/19797474/
MacIntyre CR, Cauchemez S, Dwyer DE, et al. Face mask use and control of respiratory virus transmission in households. Emerg Infect Dis. 2009;15(2):233-241. doi:10.3201/eid1502.081167
https://pubmed.ncbi.nlm.nih.gov/19193267/
Aiello AE, Murray GF, Perez V, et al. Mask use, hand hygiene, and seasonal influenza-like illness among young adults: a randomized intervention trial. J Infect Dis. 2010;201(4):491-498. doi:10.1086/650396
https://pubmed.ncbi.nlm.nih.gov/20088690/
Canini L, Andréoletti L, Ferrari P, et al. Surgical mask to prevent influenza transmission in households: a cluster randomized trial. PLoS One. 2010;5(11):e13998. Published 2010 Nov 17. doi:10.1371/journal.pone.0013998
https://pubmed.ncbi.nlm.nih.gov/21103330/
Webster J, Croger S, Lister C, Doidge M, Terry MJ, Jones I. Use of face masks by non-scrubbed operating room staff: a randomized controlled trial. ANZ J Surg. 2010;80(3):169-173. doi:10.1111/j.1445-2197.2009.05200.x
Larson EL, Ferng YH, Wong-McLoughlin J, Wang S, Haber M, Morse SS. Impact of non-pharmaceutical interventions on URIs and influenza in crowded, urban households. Public Health Rep. 2010;125(2):178-191. doi:10.1177/003335491012500206
https://pubmed.ncbi.nlm.nih.gov/20297744/
Barasheed O, Almasri N, Badahdah AM, Heron L, Taylor J, McPhee K, et al.; Hajj Research Team. Pilot randomised controlled trial to test effectiveness of facemasks in preventing influenza-like illness transmission among Australian Hajj pilgrims in 2011. Infect Disord Drug Targets. 2014;14:110–6. PubMed https://doi.org/10.2174/1871526514666141021112855
https://pubmed.ncbi.nlm.nih.gov/25336079/
MacIntyre CR, Wang Q, Cauchemez S, et al. A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care workers. Influenza Other Respir Viruses. 2011;5(3):170-179. doi:10.1111/j.1750-2659.2011.00198.x
https://pubmed.ncbi.nlm.nih.gov/21477136/
Simmerman JM, Suntarattiwong P, Levy J, et al. Findings from a household randomized controlled trial of hand washing and face masks to reduce influenza transmission in Bangkok, Thailand. Influenza Other Respir Viruses. 2011;5(4):256-267. doi:10.1111/j.1750-2659.2011.00205.x
https://pubmed.ncbi.nlm.nih.gov/21651736/
Aiello AE, Perez V, Coulborn RM, Davis BM, Uddin M, Monto AS. Facemasks, hand hygiene, and influenza among young adults: a randomized intervention trial. PLoS One. 2012;7(1):e29744. doi:10.1371/journal.pone.0029744
https://pubmed.ncbi.nlm.nih.gov/22295066/
Suess T, Remschmidt C, Schink SB, et al. The role of facemasks and hand hygiene in the prevention of influenza transmission in households: results from a cluster randomised trial; Berlin, Germany, 2009-2011. BMC Infect Dis. 2012;12:26. Published 2012 Jan 26. doi:10.1186/1471-2334-12-26
https://pubmed.ncbi.nlm.nih.gov/22280120/
MacIntyre CR, Wang Q, Seale H, et al. A randomized clinical trial of three options for N95 respirators and medical masks in health workers. Am J Respir Crit Care Med. 2013;187(9):960-966. doi:10.1164/rccm.201207-1164OC
https://pubmed.ncbi.nlm.nih.gov/23413265/
MacIntyre CR, Wang Q, Rahman B, Seale H, Ridda I, Gao Z, et al. Efficacy of face masks and respirators in preventing upper respiratory tract bacterial colonization and co-infection in hospital healthcare workers. Prevent Med 2014;62:1-7
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7172205/
MacIntyre CR, Seale H, Dung TC, et al. A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open. 2015;5(4):e006577. Published 2015 Apr 22. doi:10.1136/bmjopen-2014-006577
https://pubmed.ncbi.nlm.nih.gov/25903751/
Radonovich LJ Jr, Simberkoff MS, Bessesen MT, et al. N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial. JAMA. 2019;322(9):824-833. doi:10.1001/jama.2019.11645
https://pubmed.ncbi.nlm.nih.gov/31479137/
BEautiful. Basically this shows that it was BS (at best better than nothing at worst harmful) to wear surgical mask.
The fact N95's are so findable now makes me wonder if the real issue was undersupply of N95 or hoarding by the CCP and scalping stateside. Even then one can't just touch every surface ... then scratch their face.