COVID-19 Risks: What Does the Latest Study Tell Us?
Is eating out off the table? Are all gyms and hotels a no-go?
A new study of COVID-19 dynamics generated a flurry of scary headlines regarding the risks associated with restaurants, gyms, and hotels.
“Covid Superspreader Risk Is Linked to Restaurants, Gyms, Hotels” Bloomberg News
Should you never eat out, go to the gym, or stay in hotel, until we are all vaccinated?
It pays to dig a little more deeply and see how this study applies to your context.
What was the study?
The study, published in Nature in November 2020, was called: Mobility network models of COVID-19 explain inequities and inform reopening. It describes a model of how COVID-19 spreads that incorporates data on where people spent time. The researchers applied this model to inform risk-mitigation strategies as part of reopening efforts, and to explore the potential reasons for social inequities in the impact of COVID-19.
Thus, the most important thing to note is that this was a modeling study, not a contact tracing study. They didn’t really know where COVID-19 spread happened, but guessed based on a variety of assumptions, and examined how well their predictions matched reality.
For each location, their COVID-19 predictions were rooted in three key risk factors: i) local COVID-19 rates; ii) length of time spent at that location; iii) density of people at that location (ie. people per square foot).
The study focused on specific types of locations (which they call Points of Interest) including restaurants, hotels, gyms, restaurants, grocery stores, gas station, and other stores, but excluded other locations, like hospitals (see methods for rationale).
What did they find?
The researchers found that you could better predict COVID-19 cases over time when you take into account where people spend their time — specifically, how much time they spend in higher risk environments. Not surprising, but useful nonetheless.
They reported that a small fraction of venue types were responsible for the vast majority of new cases during the study period (March through May, 2020), and that restaurants topped the charts by a long shot. This finding is also unsurprising. It simply reflects the fact that during the spring of 2020, restaurants fit the high-risk criteria perfectly: longer visits, lots of people crowded indoors.
What are the implications of this study?
The insights in this study are extremely valuable for policy makers.
It vividly demonstrates the steep toll that cities would face if they re-opened restaurants at full capacity, without precautions, in areas with moderate to high COVID-19 rates (consistent with contract tracing studies). It also demonstrates the dramatic impact of simple risk mitigation measures, like reducing capacity.
For example, they predicted that limiting restaurants at 20% of full capacity would reduce new cases by 80% (compared to full capacity), with a lesser benefit of a lesser restriction.
The study also provided a theory on why COVID-19 has disproportionately impacted certain communities, notably disadvantaged racial and socioeconomic groups. Specifically, they propose that these communities were less able to reduce mobility, especially to higher-risk venues. If true, this insight may help guide risk-reduction strategies.
My Bottom Line
Despite this study’s value for policy makers, it doesn’t tell me or you how risky it is to eat out today at our favourite local restaurant.
In reality, two venues of the same category (e.g. restaurants, gyms, hotels) could have wildly different risk levels depending on the local COVID-19 situation and their risk mitigation strategies.
For me, this study reinforces the value of using basic principles of COVID-19 risk assessment to guide my choices. These are the big questions I always ask:
- What’s the exposure risk? How high is the local COVID-19 rate? Are sick people staying home?
- What’s the transmission risk? How many people are you exposing yourself, particularly at a shorter physical distance? How long are you in that space? What preventative measures are in place (masks, air flow and quality)
Thus, I’d feel safer in well-spaced, well-ventilated restaurant here in Vancouver (moderate COVID-19 rates) than in a small, crowded grocery store in a COVID-19 red zone.
For now, I continue to enjoy a weekly date night with hubby and an occasional dinner out with the kids. We avoid crowded restaurants, ask for an outdoor table (I pack a blanket, a scarf, and a hat!) and don’t linger very long. That said, if our local COVID-19 rates continue to head in the wrong direction, we will be moving to take-out (see Appendix for my local snapshot).
My local numbers (Vancouver, BC)
Our latest regional report showed 88 new cases per 100,000 over 2 weeks — equivalent to 6 new COVID-19 cases per 100,000 people per day (see VAN in map — 572 cases over 2 weeks per 650,000 people, Oct 30-Nov 12, BCCDC).
Unfortunately, this is likely an underestimate because cases have been steadily rising and our test positivity has climbed to 4%.
Restaurants are still open for business but we can only dine with family members (this was what I was doing anyways).
I’m a scientist and mother of three children, living in Vancouver, Canada. I completed my PhD in genetics at Stanford and spent the first decade of my career working in cancer research, drug development, and personalized medicine.
My new career chapter is dedicated to empowering others to make well-informed healthy choices, rooted in facts not fears. I’m also passionate about helping people to fall in love with the plants on their plates.
See more of my work, including articles, videos, podcasts, and healthy recipes at: https://FueledbyScience.com