Want proof of how well COVID-19 vaccines work? Just look at when they don’t.

State compiles terrific stats that show why we should be supporting more inoculations instead of fighting them.

(Francisco Kjolseth | The Salt Lake Tribune) David McCray administers a COVID-19 shot as Salt Lake City’s west-side residents get the opportunity to get vaccinated while also picking up a new winter coat and shoes for their children, thanks to a partnership among Salt Lake City, Salt Lake Education Foundation, Salt Lake City School District, Salt Lake County Health, Operation Warm and Intermountain Healthcare at Rose Park Elementary on Wednesday, Sept. 22, 2021.

During this pandemic, I’ve truly appreciated is how well the Utah Department of Health compiles and displays coronavirus data. Utah’s dashboard really is one of the better ones in the nation, and it shows information that a lot of states don’t — and I’ll leave it up to you to decide whether those states are intentionally hiding their data or just ineffectually managing it.

For example, half the states, 25, compile data on breakthrough coronavirus cases. Only 15 update that data on at least a weekly basis. And Utah, fortunately, is one of those 15.

Oddly enough, counting the number of breakthrough cases, hospitalizations and deaths — times the vaccine didn’t work — is a really effective way of telling the story of just how well the vaccine does its job. When negative outcomes are so widely happening in one group vs. another, it becomes really, really obvious just how effective being vaccinated is.

Let me show you what’s going on in our state.

We’ll start simply. Here’s the number of cases, hospitalizations and deaths per million person-days since Feb 1. (What’s a person-day? Well, it’s just the number of people times the number of days, which allows you to calculate the rate at which something happens to people. That makes sense as a method of comparison, because different people were vaccinated at different times.)

In other words, unvaccinated people in Utah have been between 4.4 times and 5.1 times more likely to get COVID-19, be hospitalized, or die because of it than vaccinated people in the past eight months.

OK, pretty straightforward. But that’s obviously been changing, right? After all, you’ve heard a lot recently (including from me, by the way) about vaccine efficacy declining as time passes. Given that the majority of those vaccinated got their shots in March, April and May, five to seven months ago, aren’t we likely to see that gap shrink?

Not so fast! It turns out that the gap has actually been growing. In other words, we’re seeing the multiplier — the ratio of coronavirus cases among the unvaccinated when compared to the vaccinated — increase over the past month.

Why is that? Well, coronavirus spread happens exponentially. Because the vaccine prevents most cases and makes other cases more mild, the contagion coefficient is higher in mostly unvaccinated communities compared to mostly vaccinated ones.

OK, slow down. What’s the contagion coefficient? you ask.

Consider the delta variant. It has a contagion coefficient of between five and nine, meaning that, without an intervention, the average infected person would share their sickness with five to nine people. Now, let’s look at some localized data.

Utah’s most vaccinated health district, by far, is Summit County’s. Impressively, 82.5% of people there have received at least one dose. Meanwhile, the two least-vaccinated health districts are Central Utah (covering Juab, Millard, Piute, Sanpete, Sevier and Wayne counties), in which 39.6% of people have received one dose; and TriCounty (covering Daggett, Duchesne and Uintah counties), in which 36.4% of people have received one dose.

If a coronavirus case happens in Central Utah, about 40% of the people around the infected person will have received at least one dose of the vaccine, leaving three to five completely susceptible people. But in Summit County, 83% of the people around the initially infected person will have been vaccinated, eliminating most of the targets of spread and resulting in nearly linear case growth.

When you compare the seven-day case rates in each health district, you can see the differences:

You can see how the cases just quickly spiked in the Central Utah and TriCounty areas, while staying much flatter in Summit County. That’s because, with a much larger pool of unvaccinated targets to potentially infect, the virus spreads from one sick person to many others much more quickly.

But each area of Utah has an impact on the others, especially when it comes to coronavirus hospitalizations. As rural hospitals fill up, they’ll often transfer patients to hospitals in more populated (and more vaccinated) parts of the state, hospitals called “referral centers.” In fact, patients are even transferred from St. George all the way to Salt Lake County, as my colleagues Erin Alberty and Scott Pierce wrote. As a result, even those in very vaccinated locations of the state may have their medical care impacted, postponed or denied by those who remained unvaccinated and made themselves susceptible to COVID-19.

Right now, our referral center hospitals are at 93.9% capacity, well above the 85% capacity limit in which intensive care units still can guarantee admission. That’s especially taxing, given a nurse and doctor shortage, as many have grown frustrated by ... well, see the above statistics ... and left the profession to seek other jobs.

While my frustration doesn’t compare to that of the medical professionals, I feel it, too. For months, I’ve been explaining to folks how the vaccine works. I’ve shown the data, comparing the risk of bad outcomes from the virus to the minuscule risk of side effects. For those who had a choice of which vaccine to get, perhaps paralysis by analysis, I created a guide to the pros and cons of each. I answered the frequently asked questions of those in my inbox who hadn’t received the vaccine. Still, I hope and work for progress. Maybe that’s irrational, but what else can I do?

It is absolutely critical that more of our state become vaccinated — critical enough that essentially any policy action on the table that leads to more vaccinations is a good one. Instead of fighting progress on vaccinations, our state should support them, however possible.

Andy Larsen is The Salt Lake Tribune’s data columnist. You can reach him at alarsen@sltrib.com.