
Prevent person-to-person transmission of SARS-CoV-2 - doener
https://www.thelancet.com/action/showPdf?pii=S0140-6736%2820%2931142-9
======
dmix
Seeing these studies and NYTimes talk about the widespread use of masks in
1918 makes me angry that in 2020 public health officials thought it was a good
idea to lie to the public for months with vague dismissals of the benefits of
masks - merely to protect supply chains for doctors (both Dr Fauci and
officials here in Canada have admitted they purposefully kept it vague for the
benefit of health care workers).

It set back a really important protocol in western countries that asian
countries had already adopted and clearly had success with. By the time they
switched on the masks-everywhere messaging we were well into the mass spread
of COVID.

This sort of "protecting people" through deception or indirection is the sort
of thing I despise from governments.

The side-effects of not immediately stating their usefulness to the public -
while no doctor would go near a COVID-19 patient without a full face + eye
mask - is still being felt today.

~~~
snowwrestler
This is not exactly what happened. U.S. medical authorities really did not
believe that basic masks, like fabric or paper surgical, offered significant
protection. Thus they believed it was N95 or nothing, and they (correctly)
wanted to save N95s for medical professionals.

They were wrong about basic masks, which is what we're all using now.

~~~
bargl
Sorry I saw an interview where Fauci said that they knew earlier that masks
would help but advised not to use them because hospitals needed the PPE. I
can't find the interview, I did a search to find articles on it though.

[https://www.businessinsider.com/fauci-mask-advice-was-
becaus...](https://www.businessinsider.com/fauci-mask-advice-was-because-
doctors-shortages-from-the-start-2020-6)

He may not have known that regular cloth coverings would help but by
discouraging the use of any masks he undercut his argument later.

Maybe - He was saying, they knew 95 masks would help but didn't know other
masks would. Either way, it feels very dishonest.

~~~
birken
Ok, you have perfect hindsight knowledge of the situation. Understanding that
N95 masks were in short supply, knowing the virus wasn't particularly
widespread, but more widespread than people realized and health care providers
are on the front lines and dealing with it already. And the science on masks
isn't fully understood either in terms of spread or protection.

What would _you_ have done, what would you have said? What would have not been
dishonest?

Also, what are you going to say so you aren't accused of: fear-mongering,
overreacting, or being wishy-washy and providing useless guidance?

~~~
renewiltord
Taiwan CDC had perfect foresight knowledge of the situation, then. Of course,
most US government agencies have massive Not Invented Here syndrome, but the
answer was obvious. And funnily enough, Tech Twitter (the subculture) was full
abuzz with this in March.

The idea that, in a situation encountering a SARS, that you wouldn't call the
guys who beat a SARS is so fundamentally silly. _Especially_ when they're
ridiculously friendly to you. That's part of what I love about startups -
every successful entrepreneur tries his best at learning from everyone else's
successes and failures. It's not enough to learn by yourself, you won't get
there in time.

So, no, I'm not surprised they couldn't do it because they have institutional
cultural failure. I don't think I could do it at the CDC either because of the
cultural failure (NIH, Perfectionism, etc.). It's hard to say, we'd have to
see the nuances of power in CDC vs NIAID, whether it would be politically
viable even for Anthony Fauci to call Chou Jih-Haw, let alone Tsai Ing-Wen
etc., and governments aren't like companies where the CEO can just set up a
team of people to bypass the normal structures and collaborate with Taiwan.
The CDC and gang may be broken beyond repair. I think that's the best defence
you can give them.

------
jcoq
This study talks about 12-16 layer cotton masks as being the most effective.
They say this offhand, as if that's a thing. However, it's very difficult to
find anything with more than 3 layers. None of the citations to that claim
give any hints about how to find 12-16 layer cotton masks (in fact, one of the
citations to that claim is a paper that couldn't determine the efficacy of one
mask-type over another).

~~~
DeRock
I think you interpreted this wrong. N95 were associated with higher reduction
in transmission than others (eg. the 12-16 layer cotton masks you mention).

~~~
jcoq
Yes, that's true, but the 12-16 layer masks were ostensibly superior to single
layer masks. The authors seem to treat "12-16 layer" masks as somewhat
equivalent to surgical masks throughout the article, which might answer my
original question.

"For the general public, evidence shows that physical distancing of more than
1 m is highly effective and that face masks are associated with protection,
even in non-health-care settings, with either disposable surgical masks or
reusable 12–16-layer cotton ones, although much of this evidence was on mask
use within households and among contacts of cases."

In another part, they compare 12-16 layer/surgical masks to single-layered
masks, ranking the single-layered as less effective.

------
xenonite
Regarding aerosols, the authors write that it is not possible to draw
conclusions yet, because they could not find enough supportive data on aerosol
transmission. Please note that they only consider sources before May 3, 2020.

------
blakesterz
Looks like what we've been hearing is backed up by this study:

"Interpretation The findings of this systematic review and meta-analysis
support physical distancing of 1 m or more and provide quantitative estimates
for models and contact tracing to inform policy. Optimum use of face masks,
respirators, and eye protection in public and health-care settings should be
informed by these findings and contextual factors. Robust randomised trials
are needed to better inform the evidence for these interventions, but this
systematic appraisal of currently best available evidence might inform interim
guidance."

I've not seen any recommendations for public use of eye protection, is that
being done anywhere? Are some places recommending wearing some type of goggles
or something?

~~~
mgkimsal
IIRC, some news reports stated Fauci mentioned something about eye-protection
last week. Haven't heard anything more concrete than that. It makes _sense_ ,
but... I doubt most people will do it. I wear glasses half the time, which...
I dunno - may be slightly useful?

~~~
johnchristopher
FWIW, as far as I am concerned, I would wear goggles if made mandatory or
highly recommended (as long as the kind of recommended googles are
sufficiently well described).

On that note I don't see anyone left wearing surgical or latex gloves outside
now (Western Europe).

~~~
thisisnico
Because the gloves are mostly pointless, if not making the problem worse. It's
better to not touch your face and sanitize your hands. All the cashiers here
don't use gloves. They sanitize their hands after every transaction, they wear
face masks, plexiglass shield around their station, and there is a limited
number of people allowed in the store, with a 1m physical distance between
customers enforced. This is the requirement in South-Western Ontario. So far
it's working fantastic over here. All decisions have been informed by
scientists and experts in their fields.

~~~
wolco
"They sanitize their hands after every transaction"

They use soap and water? Handwipes?

That must be killing any skin they have left. Gloves make so much sense for
them. They make sense for everyone.

~~~
thisisnico
They use hand sanitizer. It contains moisturizer as well.

Gloves are scientifically proven not to work unless you replace them after
every transaction, additionally most people do not know how to properly remove
surgical gloves without contamination.

~~~
wolco
That makes sense overall. But they work for the worker who wears them (just
not the public). Longer term healthy workers won't be sick and spread as much.

Taking off gloves shouldn't be an issue. I would think after a 4 hour shift
you would take them off and wash hands because they would be sweaty anyhow and
you would smell of rubber.

------
marcell
I dug through to find a few of the underlying studies on the topic of masks,
which is a controversial topic. I looked at three of the studies they cited
that had high N numbers for enrolled patients:

[1]
[https://www.medrxiv.org/content/10.1101/2020.04.20.20064899v...](https://www.medrxiv.org/content/10.1101/2020.04.20.20064899v1)

[2]
[https://pubmed.ncbi.nlm.nih.gov/12737864/](https://pubmed.ncbi.nlm.nih.gov/12737864/)

[3]
[https://www.medrxiv.org/content/10.1101/2020.04.20.20064899v...](https://www.medrxiv.org/content/10.1101/2020.04.20.20064899v1)

These studies all are focused on the protective aspect of masks: does a mask
prevent you from getting various coronaviruses? Also, they are all focused on
health care workers who interact with sick patients. The studies find that
wearing masks and taking other protective steps reduces the danger to health
care workers.

There is big a leap though, from the conclusions of these studies to global
mask mandates. Some reasons:

(1) If masks protect the individual, then individuals can make their own
decisions about mask use. If you are more concerned about getting covid, you
wear a mask to protect yourself.

(2) Health care workers interact with a lot more sick patients than the
typical person. If interact zero or just a handful of sick patients a day,
your risk calculation is a lot different than if you interact with a dozen
sick people each day.

(3) I haven't seen any studies that look at the benefit of wearing a mask all
the time as oppose to wearing a mask when you have symptoms. This would be
very interesting and relevant, since it's likely that the _most_ contagious
period is when you are sick (coughing, sneezing, sinus congestion)

In all, digging into the data doesn't really support global, 100% mask
mandates. It does support masks to protect yourself, and mask wearing in
certain situations (hospitals, for example).

------
Nuzzerino
I see on page 3 of the paper it says 118 studies were excluded for "Wrong
Outcomes" but I couldn't find any elaboration on what was meant by this. Were
papers tossed out based on arbitrary criteria? This would suggest a bias, no?

~~~
Sebguer
Outcomes in research papers refer to the specific values that were being
measured. In this case, "wrong outcomes" means that the studies that were
discarded were not measuring FOR the values that they're comparing across.

"Outcomes of interest were risk of transmission (ie, WHOdefined confirmed or
probable COVID-19, SARS, or MERS) to people in health-care or non-health-care
settings by those infected; hospitalisation; intensive care unit admission;
death; time to recovery; adverse effects of interventions; and contextual
factors such as acceptability, feasibility, effect on equity, and resource
considerations related to the interventions of interest. However, data were
only available to analyse intervention effects for transmission and contextual
factors. Consistent with WHO, studies generally defined confirmed cases with
laboratory confirmation (with or without symptoms) and probable cases with
clinical evidence of the respective infection (ie, suspected to be infected)
but for whom confirmatory testing either had not yet been done for any reason
or was inconclusive."

------
2rF7OoC47
From the study abstract:

"Our search identified 172 observational studies across 16 countries and six
continents, with no randomised controlled trials"

Don't have a chance to read the full article until later. Does anyone know if
they are controlling for confounding factors (e.g. urban/rural, public/private
settings)?

~~~
irq11
They are not. They freely mix studies from different circumstances.

For example, the “mask” section mixes data for respirators and surgical masks,
and does not differentiate between hospital or community use, source control
or PPE, when they make their top-line conclusions.

If you look at the breakouts, you’ll note that most of the data showing
effectiveness for masks is for respirator use in hospitals.

~~~
2rF7OoC47
Surely that's mentioned in the limitations of the study? In my quick scan of
the abstract, I don't recall seeing anything about it. Could have missed it
though.

~~~
irq11
It is not in the abstract.

------
pmarreck
Something I see not often mentioned (as a long-sufferer of both of them) is
that since COVID is much more highly contagious than either the standard set
of flu virii OR the standard set of rhinovirii (common cold) (what I've read,
IIRC, is that COVID is 3x more contagious than those: the median R0 for COVID
is 5.7 [https://www.healthline.com/health/r-nought-reproduction-
numb...](https://www.healthline.com/health/r-nought-reproduction-
number#covid-19-r-0) and the flu has an R0 of 1.3
[https://www.nytimes.com/interactive/2020/world/asia/china-
co...](https://www.nytimes.com/interactive/2020/world/asia/china-coronavirus-
contain.html) and the cold, 1.5
[https://www.medrxiv.org/content/10.1101/2020.02.04.20020404v...](https://www.medrxiv.org/content/10.1101/2020.02.04.20020404v1.full.pdf),
see table 1), all the work we're doing to stop COVID transmission may be
having an even greater effect on flu and cold transmission.

I talked to a biologist friend about the possibility of those being eradicated
as an unintended positive side effect of our anti-COVID efforts, and he
suggested that the animal kingdom unfortunately can serve as a zoological
reservoir of some of these viruses and could potentially retransmit them back
to humans, so it probably wouldn't entirely eradicate them, but it might
certainly drastically hamper them for years.

I for one will be happy to take "will not experience a cold or flu for the
next... who knows how many years" as a 2020 consolation prize.

Things I did not know while researching this comment:

The common cold costs the US economy $40 billion a year, and Amazon is
secretly working on a cure: [https://www.cnbc.com/2020/03/06/amazon-is-
secretly-working-o...](https://www.cnbc.com/2020/03/06/amazon-is-secretly-
working-on-a-cure-for-the-common-cold.html)

The 2018 flu season cost businesses an estimated $15.4 billion
[https://money.cnn.com/2018/02/02/news/flu-season-business-
co...](https://money.cnn.com/2018/02/02/news/flu-season-business-
cost/index.html) and sufferers $10.4 billion in hospitalizations and
outpatient expenses
[https://www.cdc.gov/flu/pdf/business/Toolkit_Seasonal_Flu_fo...](https://www.cdc.gov/flu/pdf/business/Toolkit_Seasonal_Flu_for_Businesses_and_employers.pdf)

That seems to imply that the combined economic benefit of nearly eradicating
both could result in an economic boon of $65 BILLION a year, and that's just
in the United States! Not to mention all the people who won't die of the flu,
etc...

~~~
tonyedgecombe
_but 1 flu or cold sufferer only infects an average of 1 other person)_

If that was the case then flu or colds wouldn’t spread the way they do.

~~~
francisofascii
There is not just one cold virus, there are many. So the 1-1 average sounds
reasonable.

