Sen. Lindsey Graham says he has breakthrough COVID-19

South Carolina GOP Sen. Lindsey Graham said Monday he has a case of the breakthrough coronavirus.

"I was just informed by the House physician I have tested positive for #COVID19 even after being vaccinated," Graham tweeted at about 3:15 p.m. ET. "I started having flu-like symptoms Saturday night and went to the doctor this morning."

In consecutive tweets, he also said: "I feel like I have a sinus infection and at present time I have mild symptoms. I will be quarantining for ten days. I am very glad I was vaccinated because without vaccination I am certain I would not feel as well as I do now. My symptoms would be far worse."