Washington Post fact-checker Glenn Kessler corrected himself after botching the facts in a viral Twitter thread meant to fact check President Donald Trump.

Trump took issue with a Department of Health and Human Services (HHS) inspector general (IG) report that found hospitals faced a shortage of the equipment necessary to fight coronavirus. In an April 7 tweet, Trump questioned whether the IG commissioned a report “on the failed H1N1 Swine Flu debacle where 17,000 people died?”

“Guess what, the HHS IG did do a lengthy examination of the government’s response to the swine flu in 2009. Let’s tweet out a few key findings ….” Kessler wrote on Twitter on April 7, proceeding to tweet out selections from a glowing report on the Obama administration’s handling of the swine flu.

Kessler’s thread went viral on Twitter, with the original tweet receiving nearly 6,000 retweets and more than 14,000 likes. His subsequent tweets similarly received thousands of engagements.

But the fact-checker got it wrong.

The HHS IG, a watchdog independent from the rest of the department, didn’t commission the report Kessler cited.

“The report was not an [IG] product,” IG spokeswoman Melissa Rumley told the Daily Caller News Foundation.

Kessler acknowledged the error following an email from the DCNF. He deleted the inaccurate thread and tweeted a correction.

“Rule #1: never try to do an instant fact check on Twitter. I tweeted from a government report, incorrectly saying it was an IG report, when in fact it was not,” Kessler wrote in his correction. “Dumb mistake, and I am glad it was brought to my attention. I have deleted the tweet, shown below, mea culpa.”