WASHINGTON (AP) — Two U.S. senators and a third lawmaker say they have tested positive for COVID-19 after having been vaccinated, as the nation deals with another surge in cases and the emergence of the omicron variant.

U.S. Rep. Jason Crow is the latest to announce he has tested positive. In a tweet on Sunday, the Colorado Democrat said he is fully vaccinated and got a booster shot and is experiencing only mild symptoms.

Also on Sunday, Democratic Sens. Elizabeth Warren of Massachusetts and Cory Booker of New Jersey said they have tested positive for COVID-19.

Congress was on recess Monday for the holidays, but many lawmakers were in Washington last week meeting with colleagues and others on Capitol Hill.

Crow said he tested positive after returning from an official congressional delegation visit to Ukraine.

Crow encouraged everyone eligible to get vaccinated and boosted "to help prevent major illness and protect our community." He also said he would continue to push for affordable access to rapid and reliable testing for all Americans.

In separate statements Sunday, Warren and Booker said they had been fully vaccinated with two doses and a booster and their symptoms were mild. They also encouraged others to get the trio of shots if eligible.

Warren tweeted: "Thankfully, I am only experiencing mild symptoms & am grateful for the protection provided against serious illness that comes from being vaccinated & boosted."

She didn't elaborate on where she might have contracted the virus but said she's regularly tested and turned up negative for COVID-19 earlier this past week. Spokespeople for her office didn't respond to an email seeking comment Sunday.

Warren was at the U.S. Capitol this week along with other senators as Democrats seek to pass President Joe Biden's $2 trillion social and environmental bill.

Booker, in a statement from his office, said: "I'm beyond grateful to have received two doses of vaccine and, more recently, a booster — I'm certain that without them I would be doing much worse."