Three senators said Thursday they have tested positive for COVID-19 despite being vaccinated, a high-profile collection of breakthrough cases that comes as the highly infectious delta variant spreads rapidly across the United States.

Sens. Angus King, I-Maine, Roger Wicker, R-Miss., and John Hickenlooper, D-Colo., all said they have tested positive for the virus. Almost every member of the Senate spent long hours together on the chamber�s floor last week in an all-night session of budget votes before leaving town for August recess.

King said he began feeling feverish Wednesday and took a COVID test at his doctor�s suggestion. �While I am not feeling great, I�m definitely feeling much better than I would have without the vaccine,� King said.

Wicker�s office said he tested positive for the virus Thursday morning.

�Senator Wicker is fully vaccinated against COVID-19, is in good health, and is being treated by his Tupelo-based physician,� a statement from his staff read. �He is isolating, and everyone with whom Senator Wicker has come in close contact recently has been notified.�

Hickenlooper announced his positive test a few hours later.

�I feel good but will isolate per docs instructions. I�m grateful for the vaccine (& the scientists behind it!) for limiting my symptoms,� Hickenlooper tweeted. �If you haven�t gotten your shot�get it today! And a booster when it�s available too!�

The breakthrough cases emerged the day after U.S. health officials announced plans to dispense COVID-19 booster shots to Americans. They said the shots are needed to shore up their protection against the delta variant amid signs that the vaccines� effectiveness is waning over time.

Sen. Lindsey Graham, R-S.C. had announced Aug. 2 that he had tested positive for COVID-19 despite being vaccinated. �Sending best wishes for a speedy recovery to my good friends and colleagues,� he tweeted Thursday.

�If you have not already done so please #GetVaccinated,� Graham added.

Dozens of members of Congress have reported testing positive for COVID-19. Rep. Ron Wright, R-Texas, 67, died from the disease early this year while Rep.-elect Luke Letlow, R-La., 41, died in December before being sworn into office.

(AP)