Category: Health

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Health

Tackling coronavirus vaccine hesitancy

With coronavirus vaccines coming online, I thought it about time I put a vaccine video up on the Risk Bites channel on YouTube — after all, this is exactly the type of complex yet important risk and risk communication that the channel was established to address.

I’m expecting plenty of push-back on the video from the anti-vax community, but hopefully there’ll be a greater push-forward from pro-vax, pro-science and pro-public health viewers!

I took a but of a risk here (pun intended) in addressing vaccine hesitancy. But from experience, and drawing on what’s known about effective risk/health communication, this type of approach can be helpful if you’re more interested in reaching people who are seriously interested in useful information, rather than simply preaching to the choir.

This isn’t the first vaccine video to appear on Risk Bites — in the past we’ve addressed HPV vaccines, flu shots, and MMR. But it is especially relevant to the current state of things in the world.

Hopefully this gets some traction — it’s important!

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Health

How long do aerosols stay airborne?

Just how long do SAR CoV-2 containing aerosols stay airborne once released into the air?

It’s an increasingly important question as the relevance of airborne transmission of novel coronavirus becomes apparent. Yet despite the science of aerosol dynamics being very well established, it’s surprising just how hard it is to find clear and understandable information on the settling rate of airborne particles.

This became very apparent to me when searching for a simple plot of settling velocity versus particle size that indicates just how slow or fast exhaled COVID-containing aerosols might stick around. I may be missing something but, apart from a bunch of old and quite technical plots and diagrams, there was pretty much nothing.

So I dug into my old aerosol files and created some!

Continue reading “How long do aerosols stay airborne?”
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Health Risk

Notes on estimating personal risk of contracting COVID19 while attending class (updated)

NOTE: This article was originally posted on June 28, but has since been substantially modified as I realized the initial analysis underestimated personal risk substantially. This version provides more information on the risk calculation approach taken — please treat with caution though, and let me know if you come across anything that doesn’t look right!

If you’re a student or instructor facing the prospect of in-person classes in the fall, and worrying about what the risks are of being infected by COVID19 as a result, you’re not alone.

Like many, I’ve been grappling with the potential risks of in-person teaching in the light of COVID119, and wondering just how effective measures being discussed are going to be.

Most universities are working hard to reduce the risks through measures like temperature screening, mask-usage, reduced occupancy and hybrid in-person/online teaching models. Yet without a clear sense of where these measures are backed up by evidence, I find myself finding it hard to get a good feel for what the personal risks might be.

And that’s speaking as a person who studies risk for a living!

Paying attention to ventilation in classrooms

One factor in particular that has been bothering me, coming in part from many years studying and leading research on aerosol exposure, is the rate at which potentially contaminated air in enclosed spaces is replaced with clean air, and how this in turn impacts potential risk. And as a result, I’ve been pleased to see a growing body of preliminary research looking at just this — including a recent pre-print on medRxiv from Dr.Shelly Miller at the University of Colorado, Boulder, and her colleagues, on COVID19 transmission associated with the Skagit Valley Chorale superspreading event.

Continue reading “Notes on estimating personal risk of contracting COVID19 while attending class (updated)”
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Health

How do face masks work?

Over the past few weeks, advice on using face masks and respirators to slow the spread of COVID-19 has shifted from general use being discouraged, to a growing push for widespread use–including the use of DIY face masks.

The move makes sense: reducing the potential for infected users to spread the virus through coughs, sneezes, or simply breathing, is important. Yet just because something looks like a mask, doesn’t mean that it works like one.

This is where it’s helpful to have an idea of the science behind how face masks and respirators work, and it’s why we created this short Risk Bites primer:

The primer doesn’t go as far as providing advice on how to make a DIY face mask. But it does give some insights into the science behind making a DIY face mask that is more effective. These include:

  • Recognizing that, apart from the largest particles, face masks don’t act like a sieve;
  • Using non-woven textiles if possible such as swiffer cloths or blue shop towel (as in this great article); And
  • Realizing that air–and the particles it carries–follow the path of least resistance, meaning that if there’s a leak or a gap around the edge of a face mask, that’s where the particles will go.

Of course, masks made out of whatever fabric is available are probably better than nothing (as long as they don’t make it hard to breathe, or don’t end up saturated with infectious droplets), especially where they capture or deflect large droplets from coughs and sneezes.

Yet if you know something about what makes masks work better, it’s easier to make one that’s more likely to protect the user and others, and not just look like it does.