Sen. Lindsey Graham (R-S.C.) contracted the Chinese Communist Party (CCP) virus on Aug. 2. He became infected despite already being fully immunized against the deadly disease.

“I was just informed by the House physician I have tested positive for COVID-19 (CCP virus) even after being vaccinated,” he said on Twitter.

The first fully vaccinated U.S. lawmaker to test positive revealed he began feeling unwell on July 31.

“I started having flu-like symptoms Saturday night and went to the doctor this morning,” he said on Twitter.

Graham described his symptoms as “mild” and promised to isolate himself for more than a week. 

“I feel like I have a sinus infection,” he said on Twitter. “I will be quarantining for 10 days.”

The Republican was happy to immunized against the CCP virus, and believes he would feel much worse if he did not take the jab.

“I am very glad I was vaccinated because, without vaccination, I am certain I would not feel as well as I do now,” he said. “My symptoms would be far worse.”

The congressman suspects he fell ill at a night party he attended on July 31 aboard a houseboat owned by Sen. Joe Manchin (D-W.V.).

Graham’s office confirmed the Democrat was also completely immunized, the party was outdoors, and every guest was jabbed.

“Sen. Manchin is fully vaccinated and following the Centers for Disease Control and Prevention (CDC) guidelines for those exposed to a COVID (CCP virus) positive individual,” a representative said according to Fox News.

At least seven other senators also attended the party. They include Sens. Maria Cantwell (D-Wash.), Chris Coons (D-Del.), Catherine Cortez Masto (D-Nev.), Mark Kelly (D-Ariz.), Jacky Rosen (D-Nev.), and John Thune (R-S.D.) according to CNBC.

Graham is one of 17 GOP senators who voted in favor of advancing the infrastructure bill. If a final vote is held soon, his absence–and possible quarantine of other senators–could hinder the bill’s passage through the Senate.

Graham is the Budget Committee’s ranking member, which puts him in charge of debating the $3.5 trillion spending plan. 

Since he is quarantined Politico speculates Senate Minority Whip John Thune (R-S.D.) will take over the key role.

CDC reversed its face mask guideline due to the Delta variant. Although breakthrough cases are rare and vaccines can protect people from severe illness, vaccinated people can still spread the virus to others. Masks are now required even if lawmakers are fully immunized.

The White House wished Graham a short journey to recovery.

“We certainly do hope that Sen. Graham has a speedy recovery and experiences mild symptoms, and we wish him the best of health through that,” Press Secretary Jen Psaki said in a statement. “Every single piece of available evidence shows that breakthrough infections are rare and mild.”