Tuesday afternoon’s state coronavirus data report contained a bombshell.

Abruptly, and with only a sketchy explanation, the state reported more than 8,000 new — and negative — coronavirus test results.

Here’s what we now know, 24 hours later:

Where did the results come from? Mostly from hospital tests, performed over the past two weeks. Until Tuesday, the daily state reports focused almost entirely on test results from the state’s lab and commercial labs.

Why didn’t the state report these hospital tests in the first place? The Department of Health and Welfare says it needed to weed out duplicate tests. The hospitals have been receiving test results from the state and commercial labs too. Health and Welfare needed to go through the hospitals’ reports to make sure the same negative test results weren’t counted twice.

Why were all of these new test results negative? Because the state has already included all positive results — from all sources — in its daily reports.

When it comes to preventing the spread of coronavirus, positive test results are crucial. Those are the results that help public health officials do contact tracing, identifying other people who may been exposed to the virus. That’s why all labs and hospitals are required to report all positive test results, but they’re not required to report negative results, Health and Welfare spokeswoman Niki Forbing-Orr said Wednesday.

How does all of this affect the numbers? Throwing another 8,000 negative test results in the mix has a significant impact on the percentages.

On Monday, the state reported 1,924 confirmed or probable coronavirus cases, based on 20,052 tests. In rough terms, that means about 9.6 percent of Idahoans tested are infected with coronavirus. (That isn’t precise, since some people are tested more than once.)

On Tuesday, the state reported 1,954 coronavirus cases, based on 28,240 tests. That drops the rough percentage of positive test results to 6.9 percent.

So, why the big change Tuesday? It’s no secret that Thursday will be a big news day on the coronavirus front. Gov. Brad Little will hold a news conference — and he’s likely to launch his plan to reopen most Idaho businesses over the next two months.

A spike in negative cases certainly doesn’t hurt his argument for rolling back restrictions that have closed many Idaho businesses, and all Idaho schools.

But Health and Welfare has been working since last week to clean up the data from the hospitals, and make sure the same tests weren’t counted twice, Forbing-Orr said.