Rep. Tim Ryan, D-Ohio, on Monday said he had tested positive for COVID-19 and that his symptoms would likely be much worse if he hadn’t been vaccinated, The Hill reports.

“While I’m currently experiencing mild symptoms, I’m grateful to have the protection of a safe and effective vaccine — and I know without it, this illness could be much, much worse,” said Ryan, who is currently running for Senate in Ohio.

Ryan, 48, said he will self-isolate and cast his congressional votes from home. His office noted that he tested negative for the virus three times in less than two weeks before he got a positive result.

Ten other fully vaccinated members of Congress have tested positive for COVID-19: Republican Reps. Vern Buchanan of Florida, Ralph Norman of South Carolina, Troy Nehls of Texas, Democratic Reps. Sharice Davids of Kansas, Mike Doyle of Pennsylvania and Darren Soto of Florida, as well as Republican Sens. Lindsey Graham of South Carolina, Roger Wicker of Mississippi, Democratic Sen. John Hickenlooper of Colorado and independent Sen. Angus King of Maine.

Masks are required on the House of Representatives side of the Capitol complex, with a $500 penalty for those who break the rule on the House floor. Although most legislators have complied with the safety guideline, seven House Republicans have been fined for refusing to wear masks, and many House Republicans and their staff have reportedly ignored the mask mandate in other parts of the building. The Senate does not currently have a mask mandate.