Andy Larsen: Are you ready for some football? And are you safe at games? Here’s what we know.

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It’s football time. Once again, it’s on.

But just as college football starts up around the country, we’re also experiencing the full effects of the delta variant of the coronavirus in our communities: thousands of sick people, full hospitals, quarantined family members, uncountable hours of work missed.

So at the suggestion of more than a few readers, I thought now would be a good time to look at the intersection of the two:

Are college football games safe to attend?

It’s a tricky question. Our biggest problem is that, frankly, no one in America is doing the kind of contact tracing needed to definitively answer queries like this. Our case numbers got way too big, way too fast for our often underfunded contact tracing efforts to keep up. And certainly, for the colleges themselves, counting the number of cases they were responsible for could only create the worst kind of publicity.

There have been efforts to indirectly answer the question, by looking at how cases grew in places with football games, but they’ve come up with mixed results.

Researchers from Massachusetts looked at the problem in a paper called “The Effect of NFL and NCAA Football Games on the Spread of COVID-19 in the United States: An Empirical Analysis.” Their study was pretty simple in concept. They looked at counties that had football games from both the NFL and NCAA with limited in-person attendance, and compared them to counties that either had no football games or had football games with no attendance. Smartly, they also took into account the various population sizes of the counties, whether or not they had mask mandates, and so on.

Those researchers found a difference of less than five cases per 100,000 residents in the places with fans at football games, a difference so small that it was statistically insignificant.

But a different study from the Southeast had a different conclusion. These researchers looked at the NFL alone, comparing the places where all 269 NFL games last year took place — 117 of them had limited fans, while 152 did not. And their conclusion was the opposite: that there was a statistically significant increase in counties in which games were played with at least 5,000 fans. In counties with games that had over 20,000 fans, they found 2.23 times the number of spikes than the rest of the studied counties.

So what do you do when studies like this come to different conclusions? What can serve as a tiebreaker?

For me, uncertainty makes me hunt for better data. While I appreciate the efforts of the Utah Department of Health and the Centers for Disease Control and Prevention in collecting pandemic-related data — certainly, I couldn’t do my job without them — I also know that other countries are collecting far more data, and being far more revealing with that data, than we have been in the United States.

Frankly, I wish we would have a national reckoning on why, exactly, we’ve been lapped to this degree. Whether it’s vaccination efficacy figures, variant spread, contact tracing, or hospitalization and treatment data, the truth is that you can get far more accurate, detailed, insightful numbers from nearly any other rich country. It’s unfortunate. But I digress.

While these countries don’t play football, the American sport, they do play futbol. And soccer should be quite similar to football from COVID’s perspective: large, open-air stadiums with huge numbers of fans, widespread regional support for teams, fans traveling to games from near and far, and so on. Coincidentally, a big soccer tournament, the European Championship (Euro), just happened in June and July. That’s conveniently (from a statistician’s point of view, anyway) also when the delta variant was spreading. Even vaccination numbers broadly approximated ours: About half of United Kingdom residents were vaccinated with two doses at the time.

These European countries also have incredible contact tracing. In fact, Scotland asked every one of its 63,874 coronavirus cases that occurred from June 11 to July 9 whether or not they had attended a Euro soccer game, or an event related to one. It found that 2,632 of them had.

Where did those cases get COVID? Exactly 997 of them came from people who watched a match at a bar showing the game. An additional 923 were from what the contact tracers called “Euro-related other settings” — notes from the tracers revealed that most of these were from people traveling to and from match-related events in London. Meanwhile, 239 people got their cases from a Euro-match house party, and 84 from the outdoor Euro fan zone in London.

How about at the games themselves? Turns out, 727 of the cases had attended one of the five Euro matches; of those, 452 had traveled to attend the England vs. Scotland game in London, with the other 275 attending one of four matches in Glasgow. Masks were required, though frequently went unworn. Attendance was limited to 22,500 to the game in London; and to 12,000 in Glasgow.

The Scottish contact tracers went a step further. They also found that the Euro-related cases had more secondary contacts than the rest of the population. On average, they had spent significant amount of time within close range of 5.6 people, more than the 3.2 close contacts of everybody else. Even taking into account the larger number of close contacts, those Euro-infectees were more likely to spread the virus to any single close contact, the contact tracers found. In fact, by the middle of the tournament, they found that a full 51% of all of the cases in Scotland had either been to a Euro event or were a close contact of someone who had been.

As the weeks went on, more new cases came from the ripple effects of the Euro-related cases, rather than those who attended the games themselves.

England’s numbers confirmed the spike. There, researchers found that roughly 3,404 people “in and around the stadium” of the Euro tournament’s final — which hosted about 60,000 fans — contracted the virus. And England used another tool to notice the difference: After a pandemic of roughly equal cases between men and women in the U.K., during the Euro tournament, cases spiked among men. It doesn’t take a genius to figure out what happened.

What does this show? What can we conclude from these figures?

• It seems that most of the spread related to the soccer tournament came from auxiliary events related to the games: people watching the games indoors and/or traveling to game-related events. That makes sense, given what we know about the relative risks of indoor vs. outdoor COVID spread. (This also may explain some of the results of the first study that didn’t find a statistical difference — even where stadiums didn’t allow fans in, they still likely gathered to watch the games, and probably indoors.)

• However, those who went to games certainly had elevated risks of being infected. About 1 in 200 of attendees of the Glasgow matches got COVID, while 1 in 50 of those at the England vs. Scotland match in London got COVID.

• These sports-related cases unquestionably led to an increase in coronavirus cases in their countries as a whole, first for those who attended a sports-related event, then for those who came in close contact with the sports fans, then for people who came in contact with the people who came in contact with the sports fans.

Given this data, you can understand the measures instituted by leaders at Oregon, Oregon State, Louisiana State, Tulane and a sparse number of NFL teams: Get vaccinated, show a negative test, or you’re not allowed to enter the stadium.

So what’s my advice? As always, it depends on your risk profile.

If you’re someone who has one or multiple COVID comorbidities, or are in a high-risk age group, I’d stay away from Rice-Eccles Stadium or the like this fall, with over 50,000 in attendance. I’d also stay away from the indoor environments, like bars, that would also likely result in spread.

Vaccination certainly reduces your risks significantly, especially against hospitalization, but even the vaccinated shouldn’t consider it carte blanche to participate in risky behaviors that could have huge consequences. Meanwhile, I congratulate the unvaccinated on reading their first data-oriented COVID column — and warn that you’re likely to catch the disease and face tough outcomes, if you haven’t already.

The hard bit comes for those in between: Is a risk of breakthrough infection high enough to avoid the unquestionably high fun of football? That’s something I can’t answer for your particular situation, unfortunately. You’ll want to take into account the costs of getting sick, the relatively low risk of hospitalization, and the health status of those around you before making the final call.

Andy Larsen is a Tribune data columnist. You can reach him at alarsen@sltrib.com.