By Maggie Koerth

Graphics by Elena Mejía

We all thought we knew what kinds of places to avoid: the ballparks, the Sunday services, the packed train cars. If we didn’t want to catch COVID-19, we should stay away from crowds. That was the mantra. So we skipped the summer street parties and we did virtual church. We had a nice little evening at home, ordering takeout and maybe inviting our closest friends and family over.

But now, with COVID-19 rates on the rise basically everywhere in the U.S., those small gatherings are being blamed for spreading the virus, and experts say they don’t want us to have Thanksgiving celebrations with people outside our household bubbles. But experts are always telling us not to do the fun stuff that nourishes our souls — like eating huge meals or festively increasing our drinking — while the darkness of winter encroaches from every side. Having 10 people around a Thanksgiving table can’t be that much of a risk to society, right? Surely you can’t have a superspreader event without, at least, enough people to field a football team?

Unfortunately, the last month has changed the sacrifices we must make to try to avoid the coronavirus. Across the nation, especially in the Midwest, cases have skyrocketed — with some states seeing more cases in the last six or so weeks than they’d previously had all year up to that point. Small gatherings have gotten more risky. And Thanksgiving now represents a very serious threat.

That’s because no matter how much we try to pretend otherwise, COVID-19 is a disease you get from being around other people. Technically, the size of the group doesn’t matter, said Georges Benjamin, executive director of the American Public Health Association. What matters is the likelihood that one of those people comes to the table infected.

Imagine a Thanksgiving dinner with 10 people. Unless all those people have been in strict quarantine for a couple weeks, you have no way of knowing they’re COVID-19-free. Even getting a pre-dinner test isn’t a great way to ensure you’re not contagious, experts told me, because the results are only a snapshot of a moment in time. “You could test negative today and be infectious tonight, with no symptoms until tomorrow morning,” said Donald Milton, a professor of environmental and occupational health at the University of Maryland.

How likely is it one of those 10 people is infected? That depends on where you are. Some states are estimated to have as much as an 80 percent chance of having someone with COVID-19 attend a 10-person gathering. But even if there’s a far lower chance at your individual dinner, the risk to the community of a bunch of dinners quickly becomes clear.

That is the thing that really changed in recent months. It was a slow process, said Preeti Malani, chief health officer at the University of Michigan. Over the summer, many stores, restaurants and attractions opened back up, which meant people could get together easily outside. As the weather cooled, it seems those gatherings didn’t stop, they just moved indoors. “Things started increasing, and my colleague calls it the rising water,” Malani said.

The more people who are infected in a community, the higher the likelihood that the everyday workings of a social scene will put one of them at someone’s dinner table, or on the porch at a crowded party. The more frequently that happens, the higher the waterline creeps. You can see it in action at Georgia Tech’s COVID-19 Event Risk Assessment Planning Tool, a website that calculates the likelihood that a gathering of a given size includes at least one person infected with COVID-19.

Hawaii, for example, has largely avoided the worst of this current surge. Even if you assume there are 10 times as many cases circulating in the state as have been formally diagnosed — something the folks behind the Georgia Tech recommend because of inconsistent testing and the ability of people to spread the disease without showing symptoms themselves — the risk in Hawaii is still only about 6 percent at a 10-person gathering. North Dakota, on the other hand, is one of the states that’s been hardest-hit by this current wave of outbreaks, with 1 in every 1,000 residents now dead from the virus. There, the risk of encountering a COVID-19-infected person at your small, intimate gathering was about 82 percent, factoring in the same 10x multiplier. “In February or March, when we had very few cases, there was less of a risk,” said Aditya Shah, a consultant in infectious diseases at the Mayo Clinic in Minnesota. “Now it’s so widespread … that’s different.”

The upcoming holiday season is also different, both in the literal sense and in the way Midwesterners like me use it: as a metaphor for “bad.”

Thanksgiving does not exist in isolation. It’s not a thing one family is doing alone. And it will be followed, over the next month and a half, by a series of gathering-friendly events, including Black Friday, Hanukkah, Christmas and New Year’s. Those two factors together explode a personal risk into a community crisis.

“I think about social gatherings and their impact on a community with an analogy to fire,” said Pinar Keskinocak, director of the Center for Health and Humanitarian Systems at Georgia Tech. “If you build a fire in a BBQ or a small brick fire pit, it is contained. That is how we often think about small gatherings. But if you build a fire on the ground in a pine forest which has not seen rain in months, and many other small groups do the same, you can imagine what happens very quickly.”

Risks are multiplied by dozens of dinner parties across town, and then grow over time as those dinner party attendees interact with other people in stores, waiting rooms and other small gatherings in the following weeks. This is how you get exponential growth, and it’s why experts are warning you against gathering a few loved ones at home now, even though throughout the summer all you heard about was the dangers of parties and rallies and protests and festivals, attended by dozens or hundreds or thousands of people instead of just the handful who might come to your dinner table. When there were fewer cases, it took a big gathering to make it likely that someone there was infected. But the water rose and now it’s threatening to drown us.

Again, the basic principles here aren’t new, Benjamin said. The same thing basically happens with the flu every year, he told me. Kids get exposed at school and spend the time between Thanksgiving and New Year’s passing it around from one family gathering to another. As the holidays end, flu season starts to peak.

But COVID-19 is not the flu. It’s far more deadly. It’s far more debilitating in the long term. It’s far easier to spread even if you don’t have symptoms, or don’t have symptoms yet. The virus is common enough now in a lot of places that you can’t really be confident that even a small event doesn’t include someone contagious. And holding many small events on the same day creates an opportunity for COVID-19 to spread exponentially, and disperse from Thanksgiving tables back into the community of each person who sat at them. Which just makes the risk of the next holiday higher.

It might seem unfair to ask people not to see relatives and friends they’ve missed, not to let a college student travel home for Thanksgiving dinner, not to enjoy this small pleasure. It might seem inconsistent to have focused on the dangers of large gatherings all year and begin warning about small gatherings just as they feel the most valuable. But this is a new phase of the pandemic. There’s more virus, in more places, and avoiding it has become harder. Even knowing where you caught it is harder. “The prevalence is so high in the community right now,” Shah said. “You have to see and treat everybody as infected.”