WASHINGTON — “I’m sorry to be so frustrated,” Sen. Bill Cassidy told the nation’s top public health experts, who had come to Capitol Hill to discuss the coronavirus pandemic. A practicing physician, Cassidy, R-La., was one of several Republicans who used a contentious Tuesday hearing of the Senate Health Committee to argue that the nation was moving too cautiously to reopen, in good part because caution continued to be the message from the Biden administration.

To illustrate his point, Cassidy asked one of the witnesses, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, if people “can go back to work, if they’ve been vaccinated, and not