On Wednesday, Gov. Tim Walz is expected to lift some restrictions on dining indoors and other settings that were put in place to blunt a spike in COVID-19 cases, hospitalizations and deaths that started in November but has now started to subside.

Walz announced the four week “pause”on many activities that bring people together before Thanksgiving, citing the need to keep hospitals — near full capacity at the time — from overflowing. The affected activities included dining in bars or restaurants, organized sports, gyms, wedding receptions, indoor entertainment, organized sports and social gatherings with people from different households. Some of the restrictions were extended in mid-December.

For bar, restaurant and gym owners the closures have meant significant lost revenue and some have complained about being unfairly targeted. They claim their businesses are not significant sources of viral transmission. But what do the data say?

Imperfect data

Minnesota Department of Health data through Dec. 30 show 578 outbreaks involving 8,116 COVID-19 cases believed to have originated from restaurants and bars since June, when they were first allowed to open for dining on-site, first outdoors and later, indoors.

To anyone paying attention to the COVID-19 count in Minnesota, that would seem like a very small fraction of the total number of confirmed cases in the state, which stood at 425,261 as of publication. But those numbers don’t represent the true count of outbreaks related to gathering at restaurants and bars.

First, the data come from case interviews. Case interviews depend on people answering the phone or otherwise cooperating with public health contact tracing efforts. Not everyone who tests positive is forthcoming with information about where they may have been exposed. Not only that, but it’s just the people who test positive for COVID-19 in the first place are interviewed, and many cases of COVID-19 go undetected because people, particularly younger people, are often infected but asymptomatic.

Second, an event or location has to meet an often very specific set of criteria that tell MDH with some certainty it is the origin of an outbreak to be counted.

“[The number of cases tied to restaurants and bars] just seems like a drop in the bucket when you’ve got 420,000 cases, but that doesn’t mean that it’s all the cases that were ever associated with those types of venues,” said MDH Infectious Disease Director Kris Ehresmann. “Those are a limited number of cases that meet some very specific criteria.”

That threshold for determining an outbreak has occurred is different for different types of settings. For restaurants and bars, the threshold is five people from five households testing positive within a month.  The bar or restaurant in question also has to be the only establishment the case interviewee mentions within that timeframe. For sports, it’s two or more cases in different households within a 14-day period. For other social settings and events, like weddings or funerals, it’s three cases from three different households who all attended an event, a lower bar than a restaurant outbreak since the time and location are specific.

“We’re looking for kind of those tell-tale signs of an issue, and when we do that, we see it pointing to bars and restaurants, to gyms, to different activities,” Ehresmann said. “What ends up being problematic with the public is when we describe we’ve had this many outbreaks and this many cases associated with them, in the public’s mind, that is the sum total.”

The threshold defining an outbreak in a bar or restaurant was changed from seven or more cases from different households that mentioned visiting only one bar or restaurant within a month to five in mid-November to free up staff to work on more cases, MDH spokesperson Scott Smith said in an email.

There was a spike in bar and restaurant outbreaks in November, but it’s unclear how much of that is due to the change in definition versus higher transmission, since there was also a lot of COVID-19 going around at that time compared to months prior. The elevated number of outbreaks in December, a time when bars and restaurants were closed to indoor dining, is due to delays that stem from the process of testing, reporting and interviews, per MDH.

Most of the restaurant-related outbreaks identified by MDH involved patrons, while a smaller number involved only staff. MDH conducted 84 investigations of bars and restaurants where patrons were affected that did not meet the outbreak threshold.

Making decisions

So how big a role do these outbreak numbers play in MDH’s recommendations about what should be closed and what should be open amid the pandemic?

Ehresmann said MDH uses the outbreak data as one piece of information shared with the governor designed to help guide the state’s COVID-19 response.

“We don’t have the precision we would like, but it definitely lets us know where hotspots are, because when you consider the large number of cases that we’re looking at, when you start seeing commonalities within those cases, that’s telling you that there’s something,” she said.

But outbreak data isn’t the only factor at play. Understanding how COVID-19 transmits is important as well.

“Bars and restaurants, that’s a social setting in which you have to take your masks off in order to participate in the main activity, which is eating or drinking,” Ehresmann said.  “Gyms are a setting where people are exercising, breathing deeply. The potential for spread is much greater. It’s both the data as well as what we know about these settings.”

And when it comes to decisions about what’s open and what’s closed, which fall to the governor’s office, Ehresmann acknowledged that considerations go beyond public health.

“There’s the economy, there’s those kinds of things that have to be weighed in. With the most recent opening up of gyms, there’s sort of the mental health component, there’s multiple considerations that go into these things beyond just the public health viewpoints,” she said.

Other social settings

As of Dec. 17, MDH had identified 655 outbreaks that included 4,517 cases attached to other social settings since June.

Data show sports with the most identified outbreaks, at 328 and a total of 1,290 cases. The number of outbreaks increased throughout the fall before spiking in November.

Weddings (again, threshold of three cases from three households who all attended the same event) saw a considerable number of identified outbreaks, too: 118, or a total of 1,032 cases, and peaking in October.

Gyms (outbreak threshold of seven cases from seven households within a month) have seen a total of 54 outbreaks, with 797 total cases. Gym outbreaks are no longer being tracked.