U.S. Rep. Jason Crow announced Sunday night that he tested positive for a breakthrough case of COVID-19 following his return from a trip to Ukraine.

The Colorado Democrat, who is fully vaccinated and has received a booster shot, said he’s experiencing minor symptoms.

Crow’s announcement came the same day as two other Democratic lawmakers who are also fully vaccinated and boosted, U.S. Sens. Elizabeth Warren of Massachusetts and Cory Booker of New Jersey, said they tested positive for breakthrough cases of the virus amid a nationwide spike in cases as the omicron variant surges.

“I just returned from an official congressional delegation visit to Ukraine and tested positive for a breakthrough COVID infection,” Crow said in a statement. “I’m thankful to be fully vaccinated and boosted and experiencing only mild symptoms (the vaccine is safe and effective).”

Crow encouraged everyone who is eligible to “get vaccinated and boosted to help prevent major illness and protect the wider community.” He added that he plans to “continue to push for affordable access to rapid, reliable testing for all Americans.”

Crow, a member of the House Armed Services Committee, led a bipartisan congressional delegation to Ukraine this weekend, according to a tweet from the U.S. embassy. The lawmakers discussed Russian aggression “and underscored bipartisan support for Ukraine’s sovereignty and territorial integrity and its Euro-Atlantic trajectory.”

Crow is the fourth member of Colorado’s congressional delegation to report positive test results for the virus. Last year, before vaccines were available, U.S. Reps. Ed Perlmutter and Doug Lamborn said tests showed they had COVID-19. U.S. Sen. John Hickenlooper, who was fully vaccinated, said in August that he had tested positive for a breakthrough case. All three said they were experiencing mild symptoms.

Colorado last week surpassed 10,000 deaths due to COVID-19 as the pandemic continues to spread. Since spring, health officials say, most of the deaths and serious hospitalizations are among the unvaccinated.

First elected in 2018, Crow is serving his second term representing the suburban 6th Congressional District, which covers Aurora and parts of Adams, Arapahoe and Douglas counties.