CNN anchor Don Lemon tweeted out a photo Monday evening that generated immediate backlash online.

"My #measles shot scar from childhood. Do we still need it?" he asked on Twitter.

My #measles shot scar from childhood. Do we still need it? Doctor answers on @CnnTonight 10pET. Use #VaccineQspic.twitter.com/gjoXbRflFx

— Don Lemon (@donlemon) February 3, 2015

The problem? The scar Lemon tweeted was likely not caused by a Measles shot, but rather from Smallpox vaccine — and Twitter users were quick to point that out.

"That's smallpox vaccine," one individual tweeted to him.

@thegrandfinalle@donlemon That’s no #measles vaccine. That’s smallpox vaccine.

— Xavier Tello (@StratCons) February 3, 2015

@donlemon@CNNTonight sir that's smallpox and we don't even get those anymore (in the US)

— Brianna Leigh (@raininblack) February 3, 2015

"Once in a while could you do some research before you say something?" another chimed in.

@donlemon@CNNTonight once in a while could you do some research before you say something?

— John Ratnaswamy (@JohnRSports) February 3, 2015

"[P]ut a shirt on," yet another told Lemon.

@someofmybest@donlemon@CNNTonight additionally, put a shirt on

— harriet (@lqpharriet)

February 3, 2015

The CNN anchor ultimately issued a correction shortly thereafter.

"It's a smallpox scar but all given in the sane cluster," he wrote.

It's a smallpox scar but all given in the sane cluster. #VaccineQs

— Don Lemon (@donlemon) February 3, 2015

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