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Online Discussion: Tracking new emerging diseases and the next pandemic since 2005; Coronavirus COVID-19 Pandemic Discussion Forum.

SARS-CoV-2, Masks and Fomites

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Tabitha111 View Drop Down
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    Posted: July 06 2020 at 9:09am

By Scott Weese on July 6, 2020


As we continue to work our way through the COVID-19 pandemic, balancing protection and practicality continues to be a challenge.

The desire to return to “normal(ish)” is completely understandable. However, “normal” is a long way away. It’s more a matter of what degree of “abnormal” we’re willing to tolerate (and for how long), and what degree of disease risk we’re willing to tolerate – the two are generally inversely related.


SARS-CoV-2 is a respiratory virus, and it’s becoming clearer and clearer that respiratory droplets are the main risk for transmission.

Yet, as more businesses and facilities look to re-open, the focus still tends to be on sanitization of surfaces. Yes, cleaning and disinfection is important; however, it’s not the only (or even most important) preventative measure.

Enhancing surface cleaning without taking precautions to prevent droplet spread (i.e. mask policy) is of limited benefit, and is more along the lines of “look, we’re doing something” versus actually doing something effective.


One challenge we face in designing control programs for this (and many other) pathogens is limited definitive information about the source of infections (aka source attribution).

It’s impossible to say X% of infections come from this source or that source. What we can say is based on the biology of the virus, lab testing and the patterns of spread, fomites (inanimate objects) don’t seem to be a major concern.

 A recent commentary in The Lancet entitled “Exaggerated risk of transmission of COVID-19 by fomites” (Goldman 2020) provides a nice synopsis of the issues. The first paragraph sets the scene: “A clinically significant risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission by fomites (inanimate surfaces or objects) has been assumed on the basis of studies that have little resemblance to real-life scenarios.” The article’s a commentary, not a research study, so it’s personal opinion, but it’s a good read. https://www.thelancet.com/action/showPdf?pii=S1473-3099(20)30561-2 


What’s the downside of excessive concern about fomites?


The concern is making sure people are focused on the right priorities. Cleaning and disinfection is useful. Cleaning and disinfection as the sole or main preventive approach is not good. It’s like saying I won’t worry about wearing a seatbelt, being sober or using headlights when driving at night because I make sure to check my tires before I leave. Yes, the latter is important, but it’s only going to offer a small degree of protection compared to the other items.


Yes, wash your hands regularly.


Yes, clean and disinfect common touch surfaces.


But no, you can’t stop there. Wear a mask.


Businesses that focus on sanitizing surfaces over physical distancing and mask use are doing little to stop the spread of this virus. Customers will like it because it doesn’t require them to do anything and things will feel normal, but it’s increasingly clear that masks are the key to controlling this virus.


For those of you interested in a more detailed read about masks and protection, there’s a recent modelling study of their potential effect (Fisman et al. 2020, Infectious Disease Modelling). Don’t let the equations in the methods scare you off, it’s an interesting and important paper. Here are some highlights:  https://www.sciencedirect.com/science/article/pii/S2468042720300191 


Even if masks don’t offer complete protection, widespread use can reduce the SARS-CoV-2 transmission rate. Importantly, in reasonable scenarios, it can reduce the reproduction rate (R0) to below 1, at which point the virus starts to die out, since the average infected person infects less than 1 other person.

Mask use alone doesn’t replace other efforts. There’s no single magic bullet. However, masks are a cheap, easy and effective control tool (now that they are more widely available than they were at the beginning of the pandemic, when there were severe supply shortages).

The lower the reproduction rate (R0) in the community, the less effective masks are, and less widespread use of masks can still be enough. However, if transmission in the community is not well controlled (e.g. lots of cases but no distancing or other restrictions) masks will not be enough.

As the percentage of the population that uses masks drops, the overall protective effect drops. It can drop to the point that cases continue to increase. So, mask use has to be widespread (typically through mandatory masking), particularly when disease rates are high.


Their somewhat understated but important conclusion is:


In the absence of evidence of harms done by masking, and with even preliminary evidence that they could influence epidemic growth, we suggest that their more widespread use be considered by jurisdictions which have not yet advocated this intervention.


Normalizing mask use is the key.  Mandatory masking does that.

In Wellington-Dufferin-Guelph, (Canada) it’s required. Compliance is pretty much 100%. People don’t have to feel conspicuous wearing a mask, and there’s no drama about who is or isn’t wearing a mask. It feels normal very quickly.

I think I’ve seen one person in a grocery store in Guelph without a mask in the past few weeks. In contrast, I was at a grocery store out of town this weekend in an area where masking isn’t mandatory. No staff and probably <5% of customers wore masks.

Mandatory masking rules are not meant to focus on penalties and enforcement. They’re meant to encourage everyone to act and to make wearing a mask the socially accepted approach. You don’t need a bylaw officer standing on the corner to enforce compliance – you need to make it feel normal to wear a mask.





'A man who does not think and plan long ahead will find trouble right at his door.'
--Confucius

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dutch Josh Quote  Post ReplyReply Direct Link To This Post Posted: July 06 2020 at 9:50am

DJ-Just over the border in Germany masks in supermarkets are mandatory-in NL they are not. If I would wear a mask in a Dutch supermarket I could face agression-am I spreading the virus ?

[url]https://nltimes.nl/2020/07/06/proper-ventilation-essential-fight-coronavirus-restrictions-ease-experts[/url] ;

A group of Dutch experts are calling on the government to pay more attention to proper ventilation in buildings now that people are allowed to gather in larger groups again. They do not understand why the government does not err on the side of caution on this front, a number of experts in the field of indoor climate said to AD.

At the start of this month, coronavirus restrictions were relaxed to the extent that there is no more limits to the number of people gathered inside a room, as long as they keep 1.5 meters apart. Public health institute RIVM also advised building owners to comply with the building requirements of the Building Decree.

But the importance of ventilation was given no prominence in government communication - something that experts in the field find incomprehensible, according to AD. "In other areas, they did opt for better safe than sorry. Why not here?" Francisco Franchimon, a scientist who specializes in the relationship between public health and indoor climate said to the newspaper. Philo Bluyssen, professor of indoor environment at TU Delft, and indoor climate expert Atze Boerstra agree. "Encouraging people to actively ventilate as much as possible, what could be the harm in that? Who knows how many infections you can prevent with that," Boerstra said.


The three experts AD spoke to teamed up with 236 other international scientists n a letter to the World Health Organization (WHO) and national health institutions calling on them to take the spread of the coronavirus via aerosols seriously. WHO, RIVM and the Dutch government's Outbreak Management Team (OMT) continue to insist that the role of aerosols - tiny floating droplets - in coronavirus infections is unclear, unlike the larger droplets released during coughing and sneezing. But more and more scientists are worried that these smaller droplets, which can stay in the air in an unventilated room for minutes, play a much bigger role in spreading the virus than estimated.

The risk posed by aerosols is increasingly worrisome with autumn and winter approaching - seasons when more people spend more time indoors with their windows closed against the cold. OMT expert Aura Timen warned NRC that the fall will bring a second wave of the coronavirus for that very reason.  "I don't see any reason why that shouldn't happen. This type of respiratory virus, including other coronaviruses, thrives in the winter season," she said to NRC. "In the autumn and winter we are indoors more, on top of one another."

We cannot solve our problems with the same thinking we used when we created them.
~Albert Einstein
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