Key Takeaways
- Vaxcyte’s VAX-31 matched Pfizer’s Prevnar 20 on all 20 shared serotypes and Merck’s Capvaxive on 17 of 19 in a 4,047-person Phase 3 trial.
- Prevnar brought in $6.49 billion in 2025, about 10% of Pfizer’s $62.58 billion revenue, while Capvaxive’s $759 million was about 1% of Merck’s.
- Pfizer trades at 9.87x NTM earnings and Merck at 16.36x, with VAX-31 not expected to file for approval until the first half of 2028.
Pfizer Has the Most to Lose From Vaxcyte’s VAX-31
On October 5, Vaxcyte (PCVX) said its 31-valent pneumococcal vaccine, VAX-31, met all prespecified primary endpoints in OPUS-1, its pivotal adult Phase 3 trial.
The shot produced immune responses at least comparable to Pfizer’s (PFE) Prevnar 20 on all 20 serotypes they share. Against Merck’s (MRK) Capvaxive, it cleared the trial’s stricter benchmark on 17 of 19 shared serotypes, and the other 2 met the looser threshold historically used in vaccine studies.
VAX-31 also beat both rivals on the three serotypes only it covers. Vaxcyte estimates that VAX-31 covers serotypes responsible for about 95% of invasive pneumococcal disease in US adults aged 50 and older.
Pfizer has the larger franchise at stake. The Prevnar family generated $6.49 billion in 2025, roughly 10% of Pfizer’s $62.58 billion in total revenue.
That franchise grew just 1% last year, and Pfizer cited lower US market share as a drag in Q4. Pfizer’s total revenue has also stalled, from $63.63 billion in 2024 to $63.70 billion on an LTM basis.
Why the VAX-31 Threat Hits Merck Differently
Merck’s exposure is smaller today. Capvaxive sold $759 million in 2025, about 1% of Merck’s $65.01 billion revenue, though it is the newer product still gaining ground in the US.
That makes VAX-31 more of a threat to Merck’s growth plans than to its current sales base.
The two stocks also carry different expectations. Pfizer trades at 9.87x NTM normalized earnings, near its 9.06x one-year average, while Merck sits at 16.36x against a 17.50x average.
Pfizer’s sub-10x multiple may reflect modest growth expectations, but it does not establish how much competitive risk is priced in. Vaxcyte plans to file for approval in the first half of 2028; launch timing remains uncertain.
Vaxcyte expects OPUS-2 and OPUS-3 results in the first half of 2027, testing coadministration with a flu vaccine and use in previously vaccinated adults. Positive results would support its planned 2028 filing, while Prevnar sales remain a measure of Pfizer’s competitive position.
VAX-31’s next test arrives in the first half of 2027. Follow PFE and MRK estimates as the vaccine race develops on TIKR for free →
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Disclaimer:
Please note that the articles on TIKR are not intended to serve as investment or financial advice from TIKR or our content team, nor are they recommendations to buy or sell any stocks. We create our content based on TIKR Terminal’s investment data and analysts’ estimates. Our analysis might not include recent company news or important updates. TIKR has no position in any of the stocks mentioned. Thank you for reading, and happy investing!
