Will Lower Gardasil Sales Hurt MRK's Vaccines Sales in Q1 Earnings?

Merck’s Gardasil sales fell 39% year over year to $5.2 billion in 2025, pressured by weak demand in China and Japan and a temporary shipment halt in China to reduce inventory at partner Zhifei. The article also flags declining sales across several legacy vaccines, while newer products like Capvaxive and Enflonsia are still early in their growth curves. The Zacks Consensus Estimate for first-quarter Gardasil sales is $1.18 billion, and 2026 EPS estimates have been revised down to $4.93 from $5.18 over the past 60 days.

Analysis

The market is still underappreciating how much of MRK’s vaccine optionality is now hostage to channel normalization rather than end-user demand. The temporary China shipment pause is a classic distribution reset: near-term reported sales can look worse before they get better, but the real risk is that destocking extends into multiple quarters and resets the base for 2026 estimates lower. That makes the next two earnings prints more about inventory commentary than absolute prescription trends.

The bigger second-order effect is competitive leakage. When a dominant franchise loses momentum in a market like China/Japan, competing HPV and pediatric vaccine players gain not just volume but negotiating leverage with distributors and public-health buyers. Even if MRK eventually reaccelerates ex-China, the lost shelf space and purchasing cadence can persist, especially if local partners prefer to reduce working capital exposure in a slower macro backdrop.

Enflonsia is the key offset, but the setup is still fragile because it is entering a crowded respiratory market where adoption is driven by hospital stocking and physician habit, not just label quality. That creates a lag between approval and revenue inflection, and high inventory at launch can suppress apparent uptake for 1-2 quarters even if underlying demand is improving. In other words, MRK may be in a “two-step forward, one-step back” phase where new launches are not yet large enough to absorb Gardasil friction.

The contrarian view is that the stock’s premium multiple already prices in a cleaner growth story than the fundamentals warrant. If 2026 consensus keeps drifting down while the market is still rewarding MRK as a defensive quality compounder, that sets up a valuation compression trade rather than an outright earnings collapse. The key tell will be whether management frames Gardasil as a one-time inventory issue or a structurally weaker demand reset.

Key Decisions for Investors

• Fade MRK strength on rallies: initiate a short only after any post-earnings bounce, targeting 3-6 month downside to the mid-teens P/E if 2026 EPS revisions continue to fall; stop if management quantifies China destocking as largely complete.
• Pair trade: long AZN / short MRK over 1-3 months. AZN has cleaner respiratory exposure and visible competitive momentum, while MRK faces a harder estimate-reset cycle; use this as a relative-value expression rather than a market-directional bet.
• Buy downside protection on MRK into the next print: 2-3 month puts or put spreads to capture the risk that Gardasil weakness and Enflonsia inventory effects both hit the same quarter; structure for limited premium outlay with at least 2:1 payoff.
• For event-driven investors, wait for evidence of Capvaxive acceleration before getting constructive on MRK. A cleaner launch trajectory there would be the first real offset to Gardasil degradation; absent that, upside is likely capped.
• Consider a basket short against MRK in the vaccine space if China weakness spills over to peers via distributor caution; the cleaner relative longs remain AZN and, on a more tactical basis, SNY because of better near-term respiratory visibility.