The 72-year-old Massachusetts Democrat said in a tweet that she received her positive test result on Sunday, Dec. 19 after testing negative earlier last week.
Warren said she has been vaccinated against COVID-19 and received her booster shot.
"Thankfully, I am only experiencing mild symptoms & am grateful for the protection provided against serious illness that comes from being vaccinated & boosted," Warren tweeted.
Warren urged others to get vaccinated and receive a booster shot if they haven't done so already.
"As cases increase across the country, I urge everyone who has not already done so to get the vaccine and the booster as soon as possible - together, we can save lives," she said.
During her run for the 2020 Democratic presidential nomination, Warren often spent hours posing for photos with supporters after rallies.
After dropping out of the race, she endorsed the eventual nominee, President Joe Biden.
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