A person in a mask working in a commercial kitchen area.

Taking risks with COVID-19?

biology, mathLaurie Fink, Chair of Science at the Science Museum of MinnesotaMay 23, 2020

If you’re like me, you’ve been thinking about the risks you’re willing to take for yourself and your family. Questions I ponder include:

  • How often can or should we be going to the grocery store?

  • Is it OK for my teenage children to see friends if they stay outside and promise to physically distance? Can you even trust teenagers?

  • Can my parents visit if we stay outside? What if they want a glass of water? Or if they need to use the restroom?

  • And what is the risk vs. the benefit of some of these risky behaviors?

Then last weekend I read an eye-opening blog post by Erin Bromage, PhD. Dr. Bromage is a Comparative Immunologist and Professor of Biology (specializing in immunology) at the University of Massachusetts Dartmouth. And he is a talented science communicator.

His post, The Risks - Know Them - Avoid Them, has gone viral—and for good reason. I encourage you to take the 12 minutes to read the whole thing, but I’ll outline his main points here:

The number of people getting sick is still increasing, but things are starting to open up anyway. That’s like adding fuel to the fire. I’ve checked the Minnesota numbers, and this is also true here.

A successful infection = exposure to the virus X time.
This means that quickly passing someone while walking or running outside is much less risky than a 15-minute conversation with someone in an enclosed space. A single breath releases 50–5000 droplets, likely containing 3–20 SARS-CoV2 viral particles (the viruses that cause COVID-19). Most of these droplets are low velocity and fall to the ground quickly. But a cough or sneeze releases 200,000,000 viral particles and thoroughly spreads them. The research results are still developing, but some scientists estimate that as few as 1000 SARS-CoV2 viral particles are needed for an infection to take hold.

And this is a sobering statement from the post:

“We know that at least 44% of all infections—and the majority of community-acquired transmissions—occur from people without any symptoms (asymptomatic or pre-symptomatic people). You can be shedding the virus into the environment up to 5 days before symptoms begin.”

That tells me that I don’t want to be in any closed spaces with other people.

Dr. Bromage goes on to talk about a variety of real examples of infections in different settings. My friend, a music teacher, was most upset by the example of a choir being infected by a single asymptomatic member (singing or yelling releases more droplets and viral particles than talking or breathing).

The bottom line is, the smaller the space you're in with an infected person, the more you'll be exposed to viral particles. And the longer you're exposed to viral particles, the greater your chance of becoming infected yourself.

Again, a successful infection = exposure to the virus X time

In the coming weeks, as more things open up again and we are no longer under a shelter-in-place restriction, we will all need to start making more decisions about the risks we are willing to take for ourselves, our families, and potentially our co-workers. As more people get sick, the chance of encountering someone who is infected increases as well.

Fortunately, we will also learn more about the virus, treatments, and testing, because that’s how science works. For now, be informed, weigh the risks, and consider the people around you. Wear a mask so that you don’t unknowingly spread the virus to others. Don’t be Bob (you’ll have to read the blog post to learn about Bob).