By Margaret Sullivan / The Washington Post

Some corrections are epic; like the one in The Washington Post last year that, at nearly 600 words dealing with more than a dozen errors, seemed almost as lengthy as the story itself.

Some are lame; like the “editor’s note” apology in Newsweek a few days ago that didn’t begin to embrace the magnitude of the screw-up behind the publication of a misinformed opinion piece that basically invited a revival of birtherism by stoking false, ugly theorizing about Kamala Harris’s citizenship. Newsweek’s pseudo-correction “pretends the problem was how people ‘interpreted’ or ‘distorted’ its meaning,” journalist Joshua Benton wrote. “No, the problem was the op-ed.”

Some corrections are almost laughable. A Maureen Dowd column in the New York Times erroneously implied there had been no Democratic presidential ticket with a man and a woman on it for 36 years; Hillary Clinton and Tim Kaine, some may recall, ran together in 2016. But then a Times tweet intended to point to the correction of that mistake (suggesting it had been that long since any man, regardless of party, picked a woman for his running mate) had to be corrected as well (remember Sarah Palin?).

And some corrections are almost pointless, like the one that caused Rep. Alexandria Ocasio-Cortez to light into NBC on Wednesday morning.

“You waited several hours to correct your obvious and blatantly misleading tweet,” the New York Democrat tweeted. At issue was NBC’s wording that suggested she was opposed to Joe Biden’s nomination because she submitted the routine procedural motion Tuesday night seconding the nomination of Sen. Bernie Sanders, I-Vt., during the Democratic National Convention. “It sparked an enormous amount of hatred and vitriol,” she added, and “now the misinfo you created is circulating on other networks.”

Her complaint identifies one of the problems with corrections by news organizations: They rarely — and maybe never — can undo the damage caused by the original error.

Corrections and their cousins, “clarifications” and editor’s notes, are at once utterly necessary, far too rare, and frequently useless. Once the mistake is out there, there’s no pulling it back.

In Ocasio-Cortez’s case, that original incorrect framing may have influenced the viciously unfair treatment she got on the New York Post’s front page Wednesday morning, with the huge headline about her supposed dissing of the former vice president: “AOCYA, JOE!” followed by a sub-headline of “Left hook: Socialist firebrand doesn’t even mention Biden in speech.”

In fact, Ocasio-Cortez said weeks ago that she would support Biden, despite her initial backing of Sanders. She spoke about Sanders on Tuesday night as part of the technical process of acknowledging the delegates he had earned and supplying a nomination for the convention’s roll call.

But the damage was done.

Brian Kilmeade falsely characterized her speech on “Fox & Friends”: “One of the biggest stories has to be AOC coming out and endorsing Bernie Sanders,” he said Wednesday morning. It’s impossible to know where Kilmeade got the original nugget of inspiration for this less-than-brilliant analysis, but NBC’s tweet may well have bolstered it.

And with that, NBC’s mistake and correction join the annals of corrections that — necessary as they are — don’t really get the job done.

Take, for example, another high-profile correction, one appeared tucked underneath a dubious argument by Trump campaign official Mercedes Schlapp in RealClearPolitics taking aim at CNN’s Brianna Keilar. The two had previously sparred on-air, with Keilar challenging Schlapp’s assertion that vote-by-mail is plagued by fraud.

In her piece, Schlapp charged that Keilar had “lied” while fact-checking her claims about Nevada’s new vote-by-mail statute. More egregiously, she alleged that Keilar’s husband was “a ferocious opponent of the president,” implying that the entire family must be aligned against Trumpworld. As the awkward correction later acknowledged, Schlapp’s description of Keilar’s husband was “based on the author’s misidentification of a Twitter account by a man with the same name.”

That’s a pretty big “oops,” and Carl Cannon, RealClearPolitics’ Washington bureau chief, acknowledged as much in a lengthy editor’s note in which he also states that describing Keilar’s fact-check as a lie was unwarranted. Calling Keilar a liar is not addressed in the correction itself, though.

And how many people will see such a note, anyway?

That’s another part of the problem. A faulty story may appear on a printed section front or an online home page or a prime-time network program. A correction will be hidden on an inside page or at the bottom of the online version of a story, or will be mentioned in passing at the end of a show. (Some publications put important corrections at the top of online articles, not the bottom, as with The Washington Post article mentioned earlier.)

And of course the even more troubling truth about corrections is that small errors are easy to correct. Big sweeping misconceptions — false narratives, misleading framing of global situations — far less so.

As inadequate as corrections often are, news outlets that publish them are trying to do the right thing, or at least fend off endless rounds of criticism. Still, most of these efforts end up in the inglorious category best described as “better than nothing.”

Margaret Sullivan is The Washington Post’s media columnist. Previously, she was the New York Times public editor, and the chief editor of the Buffalo News, her hometown paper.