WASHINGTON (Reuters) -President Joe Biden on Friday picked his former COVID-19 policy coordinator, Jeff Zients, to be the next White House chief of staff, citing his expertise in health care and the economy. Zients will replace Biden’s current chief of staff Ron Klain, the statement said. “I’ve seen Jeff Zients tackle some of the toughest issues in government,” Biden said in a statement announcing the move. Klain, a longtime aide and adviser to Democratic presidents and vice presidents, has been chief of staff to Biden since he took office in January 2021. It is not unusual for presidents to r…