(CNN) A White House official and a senior aide in House Speaker Nancy Pelosi's office, who are both fully vaccinated, have tested positive for Covid-19, CNN has learned.
A White House official confirmed that the White House staffer tested positive off campus.
"In accordance with our rigorous COVID-19 protocols, the official remains off campus as they wait for a confirmatory PCR test. The White House Medical Unit has conducted contact tracing interviews and determined no close contacts among White House principals and staff. The individual has mild symptoms," the official said.
"We know that there will be breakthrough cases, but as this instance shows, cases in vaccinated individuals are typically mild," the official continued. "The White House is prepared for breakthrough cases with regular testing. This is another reminder of the efficacy of the COVID-19 vaccines against severe illness or hospitalization. We wish our colleague a speedy recovery."
The White House official has not had any recent contact with President Joe Biden, another administration official said.
A second administration official told CNN, "If the vaccines are 90-95% effective, you're going to have 5-10% of the vaccinated population who either test positive but are asymptomatic or have mild symptoms. What you won't have are members of the vaccinated population going to the hospital with a severe illness or dying."
Axios was first to report the breakthrough cases.
Pelosi Deputy Chief of Staff Drew Hammill said in a statement to CNN that the speaker has not had contact with the individual in her office who tested positive since exposure, which Hammill said occurred after contact with Texas Democrats last week.
"Yesterday, a fully-vaccinated senior spokesperson in the Speaker's Press Office tested positive for COVID after contact with members of the Texas state legislature last week," Hammill said. "This individual has had no contact with the Speaker since exposure. The entire Press Office is working remotely today with the exception of individuals who have had no exposure to the individual or have had a recent negative test. Our office will continue to follow the guidance of the Office of Attending Physician closely."
White House press secretary Jen Psaki acknowledged that there have been prior breakthrough cases among White House staffers in addition to the fully vaccinated official first reported on Tuesday.
"There have been. I will say that we, according to an agreement we made during the transition to be transparent and make information available, we committed that we would release information proactively if it is commissioned officers," Psaki said when asked if there had been other breakthrough cases among White House staff.
Psaki later clarified the White House official who tested positive was not a commissioned officer but declined to say what office the official worked in, citing privacy concerns. None of the other positive cases were commissioned officers, either, she said, explaining that the White House would have proactively released that information.
Six Texas lawmakers have tested positive for Covid-19 since Friday night. The lawmakers are part of the group that left Texas, flying from Austin to Washington to break the state House's quorum and block Republicans from passing a restrictive new voting law. Officials with the group told CNN that all of the lawmakers participating in the quorum break trip are fully vaccinated, including those who have tested positive for Covid-19.
This story has been updated with additional developments Tuesday.