Thread by @phillyrich1

I'm going to try to save some lives today. Here's a timeline of the science behind wearing masks. I believe the messaging about "wear a mask" may be the problem. There is no scientific basis to believe CLOTH masks prevent the spread of COVID.

1/23: NYT "Many in China Wear Them, but do Masks Block Coronavirus?" The chairperson
of the public health committee for the Infectious Disease Society of America: "surgical masks are really
the last line of defense."

“...we worry about people feeling they're getting more protection from the mask than they really are. Bc surgical masks aren't fitted or sealed, they
leave gaps around the mouth so you're not filtering all the air that comes in.” This comment was about surgical, not cloth masks.

2/29: Surgeon Gen'l J. Adams tweeted: “Seriously People Stop Buying Masks. They are NOT effective in preventing general public from catching
#Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them &
our communities at risk!”

Dr. Adams was referring to surgical masks, not cloth masks.

3/3: The Cochrane Clinical- “Can Physical Interventions Help Reduce the Spread of a Respiratory Virus?"
They concluded that the evidence suggests that
some physical interventions may reduce the spread of respiratory viruses, particularly hand washing, wearing of masks, gowns,...

and/or gloves, but most evidence is of very low certainty.
Again, the masks assessed here were surgical, not cloth masks. The Cochrane reviewers
went on to say that the results are not consistent across all studies and reviewers classified the
evidence as very low certainty.

So, at that point, their review results did not provide strong
evidence to support that you should use surgical masks to reduce the spread of respiratory
viruses.

4/1: The National Academy of Medicine- “While the current SARS-CoV-2 research is limited, the results of available studies are consistent with the aerosolization of viruses from normal breathing.” This becomes critical wrt effectiveness of cloth masks with COVID transmission.

4/3: CDC published "Recommendation regarding the use of cloth face coverings, especially
in areas of significant community-based transmission," stated that “In light of this new evidence,
CDC recommends wearing cloth face coverings in public settings...

where other social distancing
measures are difficult to maintain especially in areas of
significant community-based transmission.” The new evidence the document was referring to
was investigation reports and studies demonstrating presymptomatic or asymptomatic
transmission.

The recommendation was published without a single scientific paper or other information provided to support that cloth masks actually provide any respiratory protection.

Shortly after CDC published their recommendation U.S. Surgeon General Dr. Jerome
Adams changed his “do not use surgical masks recommendation” to one supporting the CDC
cloth mask recommendation. Again with no new data on how cloth mask use reduces the risk of
virus transmission.

4/6: WHO came out with their interim
guidance on the use of masks in the context of COVID-19. "There is limited evidence that
wearing a medical mask by healthy individuals in households, or among contacts of sick patients,
or among attendees of mass gatherings,

may be beneficial as a preventative measure. However,
there is currently no evidence that wearing a mask, whether medical or other types, by healthy
persons at a wider community setting, including universal community masking can prevent them from infection with respiratory

viruses including COVID-19.” This recommendation is not just about surgical masks, which they're calling medical masks, but also cloth masks.

4/8: National Academy of Sciences- “There are no studies of individuals wearing homemade fabric masks in the course of their typical activities, therefore we have only limited and indirect evidence regarding the
effectiveness of such masks protecting others when made or worn

by the general public on a regular basis. The evidence comes primarily from laboratory studies testing the effectiveness of different materials at capturing particles of different sizes. The evidence from these laboratory
filtration studies suggest that such fabric masks may

reduce the transmission of larger respiratory
droplets, but there is little evidence regarding the transmission of small aerosolized particulates
of the size potentially exhaled by asymptomatic or presymptomatic individuals with COVID-19.

4/19: UNCOVER- "Does the
use of face masks by the general population make a difference to the spread of infection?"

"Mask wearing alone, in the absence of other
preventative measures, is unlikely to be effective, yet most studies do not take this into account.”

4/21: Statistical model was made public with great fanfare by a group of five researchers, none of whom have expertise in aerosol science or respiratory protection concluding
that universal masking should be made mandatory to significantly reduce SARS-CoV-2
transmission.

They determined in their model that if 80% of the population used cloth masks COVID-19 incidence could be reduced to one twelfth of what it is today. The lead author is De
Kai, a computer science expert.The results of this modeling study has been the basis for people making major

policy decisions about requiring the use of cloth masks despite all the other cloth face mask reviews that have been conducted. Unfortunately to criticize, De Kai’s group’s efforts has meant being on the receiving end
of the wrath of people who believe its findings.

5/14: USF Jeremey Howard published The Conversation and formed a group called MASKS4ALL.
Howard stated in The Conversation article that based on the findings from the model by De Kai, mandatory masking with cloth masks could be amongst the most powerful tools
to stop COVID.

This statement was not supported by any peer reviewed data. He has also stated publicly that he has identified 34 papers showing the effectiveness of cloth masks and none that show otherwise. Such a statement is totally baseless and reckless.

5/24: NYT- “The Most Patriotic Thing You Can Do Right Now.” There is a link in the editorial to support the science statement, and it is a 5/8 article in Vanity Fair, for which the article cites as its primary expert source the data from the yet unpublished De Kai model.

Finally, there is the fact that only one study has been conducted that was a randomized trial of cloth masks compared with surgical masks. It was carried out in healthcare workers, not the general public.

In short, the study found that those that wore the cloth masks had 13 times more infection outcomes than those that wore surgical masks. The filtration testing for the cloth mask was 97%. Only 3% of the particles in that test were stopped by the cloth material.

We owe the public much more. The preponderance of scientific evidence supports that aerosols play a critical role in the transmission of COVID. Any respiratory
protection respirator/mask must provide a high level of filtration & fit to effectively prevent transmission of COVID.

Public message on cloth mask effectiveness that is provided to the medical
community, public policy leaders and the general public must be based on sound scientific data
and currently it is not.

Many in the general public are currently using cloth masks in public to protect themselves and others. They should be made aware that these masks may provide some benefit in reducing the risk of virus transmission, but at best it can only be anticipated to be limited.

SOURCE: Michael Osterholm, COVID 19 Advisor to Joe BIden.

cidrap.umn.edu/sites/default/…

MY COMMENT: If people are wearing CLOTH masks bc they were told that would stop the spread, they may be putting themselves and others in risky situations and thereby actually causing the spread, not preventing it.