Rep. Kay Granger (Texas), the top Republican on the House Appropriations Committee, announced on Monday that she tested positive for COVID-19 after arriving in Washington for the start of the new session of Congress.

Granger's positive test came after she received her first dose of the Pfizer-BioNTech COVID-19 vaccine that the Capitol physician began distributing to members of Congress last month.

Granger was tested for COVID-19 on Sunday and is not feeling symptoms, according to her spokesperson.

“When she arrived in DC for the beginning of the 117th Congress, Congresswoman Kay Granger was tested for coronavirus in accordance with the Attending Physician’s guidance for Members when traveling from their home state. She was later notified that she tested positive and immediately quarantined. Having received the vaccine in December, she is asymptomatic and feeling great! She will remain under the care of her doctor," Granger spokesperson Sarah Flaim said in a statement.

Before learning of her positive test, Granger participated in House floor votes on Sunday, including the Speaker election.

Members of Congress are advised to be tested for COVID-19 upon arrival in Washington, but can still go about their regular business while awaiting their results if they don't have symptoms or any known exposure to the virus. The Capitol's testing system provides results within one day at the most, although often in a matter of hours.

The Pfizer-BioNTech vaccine is shown to provide some protection against COVID-19 about 10 days after receiving the first dose, but the second dose provides a longer-term boost.

Pfizer has said that the vaccine efficacy after the first dose is about 52 percent, but it goes up to 95 percent after the second dose — which is administered three weeks later.

House Democrats implemented proxy voting last May to allow lawmakers to authorize a colleague to cast votes on their behalf if they are sick or must quarantine. But those rules changes expired with the end of the previous session of Congress and won't be renewed until the House adopts a new rules package for the new session later Monday.

Most Republicans, including Granger, have not utilized proxy voting during the pandemic.

In the meantime, the Capitol physician approved the installation of a Plexiglass box in the visitors' gallery overlooking the House floor so that lawmakers who have tested negative but are supposed to be quarantining from possible COVID-19 exposure could cast votes. And for the last several months, House members have been asked to vote in groups while quickly exiting and entering the chamber to limit the number of people in the room at a time.

Nevertheless, many members in both parties crowded on the House floor during an unexpected floor vote on Sunday evening. That prompted Speaker Nancy Pelosi (D-Calif.) to issue a stern reminder to lawmakers on Monday morning to adhere to social distancing measures and wear masks while the pandemic is ongoing.

"When staff urge you to leave the floor, it is not a suggestion. It is a direction, in the interest of keeping the Congress healthy and intact," Pelosi wrote.

Granger previously had to quarantine in July after she sat next to Rep. Louie Gohmert (R-Texas) on a flight from their home state days before he tested positive for COVID-19.

Two other House Republicans also tested positive for COVID-19 in recent days: Reps.-elect Maria Salazar (Fla.) and David Valadao (Calif.). Both missed the opening day of the new session on Sunday and will have to be sworn in at a later date once they are cleared to travel.

Rep. Gwen Moore (D-Wis.) also announced last week that she had tested positive for COVID-19, but said she received medical clearance to travel after quarantining for two weeks and participated in votes on Sunday.

At least 49 members of Congress or lawmakers-elect have tested positive for COVID-19 since March, while several others have tested positive for antibodies or had presumed cases.

Rep.-elect Luke Letlow (R-La.) died last week from COVID-19 complications at the age of 41, days before he was set to take office on Sunday.