Pakistan, Jan. 23 -- When the US walks out of the World Health Organisation this week, the paperwork will look tidy, and the politics will look triumphant. After all, a year's advance notice was provided, and the move feeds well into the America First banter often peddled by President Donald Trump. The consequences will, however, be neither. Washington's departure lands with a bill still unpaid-about $260 million in arrears, and with legal questions at home over whether the exit complied with Congress's conditions of notice and payment. Global health is not a club you storm out of without splashing everyone nearby.

WHO is flawed, and the pandemic exposed it. Yet the argument that reform requires abandonment is an expensive distraction fr...