Doctor Claire Poche, a senior health adviser for the Oregon Health Authority, donned white and red clown makeup and a red tie with a polka dot shirt in the sombre clip.
In the bizarre video, Dr Poche announces statistics on recorded cases of the virus and deaths while wearing the costume and maintaining a straight face.
“As of today, there have been 38,160 cases of Covid-19 in Oregon, with 390 new cases being reported today,” she said.
She then goes on to discuss the state's death toll, adding: “Sadly, we are also reporting three deaths today, bringing the statewide total for Covid-19-related deaths to 608.”
The costume was actually part of a discussion on celebrating Halloween safely during the pandemic.
Another senior adviser Shimi Sharief later appears in the announcement dressed in a cuddly animal onesie from the film My Neighbor Totoro.
The clip, which aired on 14 October, went viral on Twitter after Oregonian journalist Samantha Swindler called the production choice an “absolute nightmare”.
“I'm sorry but who at the Oregon Health Authority thought this was a good idea?”, she wrote on Twitter.
The post has gained significant attraction since Tuesday, receiving more than 7,800 likes and 3,300 retweets.
“I get they were going for a ‘fun’ Halloween Covid update and they have a very hard job but this … this does not work,” she added.
“One of the great things about this video (and there are many great things) is they never acknowledge or address the costumes. The clown is just THERE and she dives right into the numbers. AMAZING STUFF.”
She then urged people to wear masks and social distance so that doctors do not have to repeat videos such as these.
Some users interpreted the appearance more harshly and applied it as a negative reflection of Oregon officials' handling of the pandemic.
“Oregon. Literally run by clowns,” Douglas Murray, associate editor at The Spectator, wrote.
“Federal Covid response: metaphorical clown show. Oregon Covid response: literal clown show,” one user said.
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