By Mariam Sunny and Michael Erman

(Reuters) -Merck ( MRK ) said on Monday it expects a commercial opportunity exceeding $5 billion from Cidara Therapeutics' ( CDTX ) experimental flu drug, and does not anticipate it to require a review by the U.S. CDC's vaccine advisory panel before launch.

The U.S. drugmaker announced a nearly $9.2 billion deal last week to acquire Cidara, aiming to gain access to its long-acting antiviral, CD388, currently in late-stage trial.

CD388 is not a vaccine and is designed to be effective regardless of a person's immune status and could offer single-dose, universal protection against all flu strains.

Vaccine policy in the United States has been undergoing a shift under Health Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic, who has revamped the Centers for Disease Control and Prevention's panel of outside advisers and prompted the ouster of its director.

"I would not say that our view of what is happening around vaccinations has in any way affected either our view of vaccinations or what drove us to this (drug)," Merck ( MRK ) CEO Robert Davis said during a call with analysts.

Merck ( MRK ) expects about 110 million Americans to be eligible to receive CD388, including 85 million considered at high risk for influenza. It plans to manufacture the drug long-term at one of its U.S. facilities.

The company said it expects Cidara's acquisition to reduce earnings by about 30 cents per share over the first 12 months from the deal's closing, reflecting investments to advance CD388 and the assumed cost of financing.

The deal is expected to close in the first quarter of 2026.