An update on the corona virus and its behavior the past couple months.

An August 12th podcast from Dr. Michael Osterholm warns of the paucity of protection offered by cloth masks, as well as more info about how the delta virus was spreading. The podcast is two months old, so the content about the spreading is dated but still alarming. The content about masks is still valid although it may conflict with what you may have read in the press or social media or heard on TV. Warning: the podcast is nearly 90 minutes long, but well worth the time.

From other sources (sorry, I cannot find the exact place I found these stats; this link is the closest):

  • A cloth mask blocks ~5% of particles and aerosols. Multiple cloth masks do very little better blocking leakage.
    • A well-fitted surgical mask, the kind with pleats at the sides, blocks ~40% of particles and aerosols. Note: “well-fitting” is highly problematic due to leakage around the sides. Men with facial hair cannot get a good fit; they must shave it off for the mask to be really effective. And of course it must be worn over the nose. A video that shows how you can reduce leakage; no info on its effectiveness, but since other sources I have found have said that 90%+ of surgical mask leakage is at the sides, it seems like the knot-and-tuck procedure has to reduce leakage.
    • An N95 facemask blocks ~95% of particles and aerosols. Ditto the comment about facial hair. (This is extremely unwelcome news to Smoke and I. He has only been beardless once or twice during our nearly 47 years of marriage. The one time that I remember him shaving it off, he woke me up to ask what I thought. I said, immediately, “Grow it back.”)

I wore an N95 mask for most of the first year of the pandemic; Smokey had a box of them he had bought back in the day when he was going to be sandblasting or spray painting. But they irritated my [ultrasensitive/snowflake] skin, so I was repeatedly sticking my finger under the mask to relieve itching and irritation. In that circumstance I figured I was ultimately negating the benefit of the N95 mask. Eventually I found a satin mask online and have been wearing it instead. Now that I know about the ineffectiveness of a cloth mask I shall wear an N95 over it for both comfort AND protection. Sadly, I do not remember which if any of the links go to the satin mask I bought, but mine has a nose wire, a pocket for a filter (4 came with the mask) and a small dart to make it hook under the chin.)

From the CIDRAP website:

The spread of COVID-19 is a function of distance, duration, and air circulation. Avoid the three C’s: closed spaces, crowds, and close contact. 

Ventilation is the key to reducing risk, which is why outdoor spaces involve a much lower risk of virus transmission. Outdoors is best, but any barrier such as a tent or awning could theoretically reduce the ventilation and therefore increase the risk of exposure. There are documented outbreaks from crowded outdoor events, so being outdoors is not without any risk. For more information, listen to the Osterholm Update: COVID-19, Episode 56: From Checkers to Chess (38:00).

Double masks are not clearly an improvement over a single mask, because protection is based on fit and filtration (how well viruses are filtered out). Doubling up masks may change the fit and increase leakage. N95 respirators are clearly the best in terms of preventing inward and outward leakage. Three-layer masks and neck gaiters worn properly (always over the nose) offer the most protection for the wearer and those around, but the protection is limited. Three-layer masks and neck gaiters buy the wearer time in acquiring an infectious dose, but they do not offer substantial protection and are not good for long periods. For more information, listen to the Osterholm Update: COVID-19, Episode 42: Calling an Audible (42:45) and the Osterholm Update: COVID-19, Episode 44: Hurricane Warning (37:00). 

Wearing a cloth face covering is not permission to get close to others or go into crowds. It is merely an added layer of protection for both the wearer and others. Cloth masks and face coverings likely do not offer the same degree of protection as physical distancing, isolation, or limiting personal contact time. A cloth mask or face covering does very little to prevent the emission or inhalation of small particles; therefore, the level of protection may not be substantial. For more information, listen to the Osterholm Update: COVID-19, Special Episode: Masks and Science and the Osterholm Update: COVID-19, Episode 56: From Checkers to Chess (30:00).

Clear face shields are not a replacement for cloth face coverings or masks. The CDC states, “It is not known if face shields provide any benefit as source control to protect others from the spray of respiratory particles. CDC does not recommend use of face shields for normal everyday activities or as a substitute for cloth face coverings.” For more information, listen to the Osterholm Update: COVID-19, Episode 19: No Time to Rest (36:35). 

The science is unclear if 6 feet is sufficient to prevent the spread of COVID-19, although evidence suggests that 6 feet is not enough, and 3 feet is certainly not enough. Most published data on aerosol and droplet spread is not specific to SARS-CoV-2, but the science strongly points to longer distances than 6 feet, sometimes substantially more. For more information, see “Short-range airborne route dominates exposure of respiratory infection during close contact,” “Theoretical analysis of the motion and evaporation of exhaled respiratory droplets of mixed composition,” and “Study of SARS transmission via liquid droplets in air.”

More from the CDC:

Methods:

Seven participants first evaluated N95 and KN95 respirators by performing a fit check. Participants then underwent quantitative fit testing wearing five N95 respirators, a KN95 respirator, a surgical mask, and fabric masks.

Results:

N95 respirators offered higher degrees of protection than the other categories of masks tested; however, it should be noted that most N95 respirators failed to fit the participants adequately. Fit check responses had poor correlation with quantitative fit factor scores. KN95, surgical, and fabric masks achieved low fit factor scores, with little protective difference recorded between respiratory protection options. In addition, small facial differences were observed to have a significant impact on quantitative fit.

Conclusion:

Fit is critical to the level of protection offered by respirators. For an N95 respirator to provide the promised protection, it must fit the participant. Performing a fit check via NHS self-assessment guidelines was an unreliable way of determining fit.

* * * * * * * * *

It will be a bit before I get caught of with Dr. Osterholm’s weekly podcasts, but if there are things that I feel that y’all need to know ASAP, I will post them.

::stepping down from my soapbox::

This entry was posted in Coronavirus. Bookmark the permalink.

2 Responses to An update on the corona virus and its behavior the past couple months.

  1. k says:

    October 5th, 2020, was the day sentient yam returned to the White House from his little adventure at Walter Reed – the one where he was posting proof of life videos? And driving around maskless in a sealed car with Secret Service agents? It seems like a decade, not a year.
    We live a pretty sheltered life up here, but I think we’ll up our mask protocol. Daughter “is” Moderna, and only 5 months out; I got a Pfizer booster last week.

  2. k says:

    The first 6 minutes are informational on other vaccines helping to develop your immune response in general –

    The rest of it – eh.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s