Does a whistleblower have to sustain economic damages to bring a claim?

No.  As the ARB held in Dugger v. Union Pacific Railroad Co., ARB No. 16-079, ALJ No. 20156-FRS-36 (ARB Aug. 17, 2017), the “issue of whether a complainant has sustained damages has never been a prerequisite to a finding of retaliation; ‘the absence of a tangible injury goes only to remedy, not to whether the employer committed a violation of the law.'”

Actionable retaliation is not limited to tangible job consequences.  The inquiry is whether a company’s actions well might have dissuaded a reasonable worker from engaging in protected conduct.  Burlington Northern & Santa Fe Railway Co. v. White, 548 U.S. 53 (2006).  Indeed, merely “outing” a confidential whistleblower is actionable retaliation under the Sarbanes-Oxley whistleblower law.