Jimmy Fallon reveals he tested positive for COVID-19

Jimmy Fallon is opening up about his experience with COVID-19.

The Tonight Show host wrote on Instagram that he tested positive "on the first day of our holiday break" but only experienced "mild symptoms".

Fallon said he is vaccinated and has had a booster.

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"Thank you to the doctors and nurses who work so hard around the clock to get everyone vaxxed," he wrote.

"Thank you to NBC for taking the testing protocols so seriously and doing a great job - and also thanks for putting me in the 'What 'chu talkin' about Willis?' isolation room when they told me the news."

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Celebrities, including Reese Witherspoon, left well wishes for the Tonight Show host in the comment section of his post.

"Hope you had a speedy recovery!" Witherspoon wrote.

"Feel better soon ! We all love you I mean, like … EVERYBODY !!!" singer Debbie Gibson wrote.

Musician Morris Day said: "Feel better soon Brotha Jimmy".

While Broadway and Hollywood star Kristin Chenoweth commented: "Jimmy please rest. Eat. Repeat. Feel better."

The Tonight Show returned Monday night with guests Anthony Anderson and Carly Pearce.