Sen. Elizabeth Warren tests positive for COVID-19

Sen. Elizabeth Warren has tested positive for COVID-19.

The Massachusetts Democrat announced her positive test on Twitter Sunday afternoon. Warren is fully vaccinated, meaning she has contracted a breakthrough infection.

"I regularly test for COVID & while I tested negative earlier this week, today I tested positive with a breakthrough case," Warren tweeted. "Thankfully, I am only experiencing mild symptoms & am grateful for the protection provided against serious illness that comes from being vaccinated & boosted."

COVID-19 cases across the globe have started to rise again in recent weeks. And the arrival of the highly-infectious omicron variant threatens to push case numbers even higher.

Experts have routinely called vaccinations the best weapon at combating the spread of the virus and keeping hospitals from becoming overwhelmed. Warren encouraged Americans who have not been vaccinated or received a booster dose to schedule an appointment to do so.

Sen. Elizabeth Warren, a Democrat from Massachusetts, speaks during a Senate Banking, Housing and Urban Affairs Committee hearing in Washington, D.C., U.S., on Tuesday, Nov. 30, 2021. (Photographer: Al Drago/Bloomberg via Getty Images)

"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," Warren said.

This story was reported from Atlanta.