RICHMOND — State Sen. Bryce E. Reeves said Tuesday that he has tested positive for the novel coronavirus, making him the first state legislator confirmed to have the virus since the state Senate began meeting in person days ago for its special session.

Reeves (R-Spotsylvania) had met with Virginia’s other 39 state senators for three days last week as the session got underway. He said his first symptoms appeared the evening of Aug. 19. Reeves and most senators wore masks while in session, although they removed them at times to eat, drink and speak.

“Out of an abundance of caution, for some very mild cold symptoms I felt last week that started on Wednesday, I got tested yesterday and tested positive for Covid,” Reeves, 53, said in an email Tuesday. “As of yesterday I’m in self quarantine.”

Senate Clerk Susan Clarke Schaar alerted other senators about Reeves’s positive test in a message Tuesday, encouraging them to “seek medical attention immediately” if they experience symptoms.

“He had very mild symptoms — sore throat, coughing and sneezing,” she wrote. “If you have these symptoms or other Covid symptoms please do NOT come to Richmond!”

Reeves, who participated in an online Senate committee meeting Monday, will miss the Senate floor session while quarantined.

Schaar’s office has gone to great lengths to try to prevent senators from spreading the virus during the special session, which began Aug. 18.

Instead of meeting in the Senate chambers in the Capitol, senators have convened a few miles away in a sprawling meeting room at the Science Museum of Virginia. Their desks are spread far apart, and senators are required to wear masks.

Schaar and a staffer built a three-sided plexiglass box before the Senate’s one-day session in April to provide extra protection for Sen. George L. Barker (D-Fairfax), who had open-heart surgery and pneumonia last year.

A second box appeared last week for Sen. Amanda F. Chase (R-Chesterfield), who has worn a mask in the past but lately has said she has a medical condition that prevents her from wearing one. She has declined to discuss the condition.

Senators plan to reconvene Wednesday for the session, which Gov. Ralph Northam (D) called to address budget, policing and criminal justice issues raised by the pandemic and the killing of George Floyd while in Minneapolis police custody.

“I cannot imagine that Anthony Fauci himself could walk through the Chamber and not approve,” said Jeff Ryer, spokesman for the Senate GOP caucus, referring to the director of the National Institute of Allergy and Infectious Diseases. “The clerk’s office has scrupulously and strictly and stringently followed every guideline that the CDC offers.”

House Speaker Eileen Filler-Corn (D-Fairfax) has taken a different course to try to keep the state’s 100 delegates safe. The House tipped off the special session in a basketball arena at Virginia Commonwealth University, but after that Democrats muscled through a vote to allow the House to convene online.

After Reeves’s condition became known, Filler-Corn tweeted that the House wishes him “a full recovery. We hope that all Senators and staff are in good health and remain safe as the General Assembly handles the important business of this Special Session.”

Reeves, who sought the GOP nomination for lieutenant governor in 2017, said he thinks he may have picked up the virus by touching “a gas nozzle or a door somewhere.”

“I have zero symptoms of a fever, chills, or anything,” he said in a text message. “Literally I thought it was my seasonal allergies or a light cold. . . . I don’t feel sick.”

Gregory S. Schneider contributed to this report.