Vaxcyte Shares Skyrocket 57% After Positive Phase 3 VAX-31 Data for Pneumococcal Vaccine

Key highlights

• VAX-31 met all prespecified co-primary immunogenicity endpoints in adults aged 50 and older
• Met noninferiority criteria for all 28 serotypes shared with Prevnar 20 and Capvaxive
• Achieved superiority for three unique serotypes and cross-reactive serotype 20B
• Safety and tolerability profile was similar to existing vaccines PCV20 and PCV21
• Submission of a Biologics License Application to the FDA is planned for the first half of 2028

What Happened

Vaxcyte successfully completed the OPUS-1 pivotal trial, which evaluated the safety and immune response of VAX-31 in adults. The study confirmed that VAX-31 was noninferior to Pfizer's Prevnar 20 and Merck's Capvaxive for all shared serotypes in participants aged 50 and older. Furthermore, the vaccine showed superior immune responses for the three serotypes unique to its 31-valent formulation. Immunobridging results also indicated consistent performance in younger adults aged 18 to 49. The safety data revealed a profile comparable to current standard-of-care vaccines, with no significant adverse events distinguishing VAX-31 from its competitors during the study period.

Up 18.3% since our story on 5 Oct: $56.48 when we broke it → $66.80 at the close on 13 Oct. Daily closing prices. Source: Yahoo Finance.

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14 Sep	$59.54
15 Sep	$59.21
16 Sep	$58.77
17 Sep	$60.37
18 Sep	$58.13
21 Sep	$58.92
22 Sep	$59.02
23 Sep	$56.49
24 Sep	$56.90
25 Sep	$56.21
28 Sep	$58.27
29 Sep	$56.69
30 Sep	$56.90
1 Oct	$56.05
2 Oct	$56.48
5 Oct	$73.82
6 Oct	$66.70
7 Oct	$66.96
8 Oct	$65.02
9 Oct	$71.38
12 Oct	$70.65
13 Oct	$66.80

Significance

• Positions VAX-31 as a potential leader in broader-spectrum pneumococcal protection
• Validates the proprietary XpressCF cell-free protein synthesis platform for high-valency vaccines
• Establishes a definitive timeline for regulatory submission following upcoming OPUS-2 and OPUS-3 trials
• Confirms the ability to increase serotype coverage without diminishing the magnitude of immune responses

Business Overview

Vaxcyte is a clinical-stage biotechnology company focused on developing next-generation conjugate vaccines to prevent serious bacterial infections. The firm utilizes a cell-free protein synthesis platform, which allows for the rapid development and manufacture of complex vaccines that are often difficult to produce using traditional cell-based methods. This technology enables Vaxcyte to create vaccines with higher valency, meaning they can target more bacterial strains simultaneously. By focusing on the multi-billion dollar pneumococcal vaccine market, the company aims to address serotype replacement and provide more comprehensive protection than currently available products.

Industry Landscape

The pneumococcal vaccine sector is a mature market dominated by major pharmaceutical players, with Pfizer and Merck currently providing the primary options for adult immunization. Recent industry developments have focused on expanding the number of serotypes covered in a single dose to combat the evolving nature of invasive pneumococcal disease. While 20-valent and 21-valent vaccines are currently the standard, there remains a significant public health need for even broader coverage as new strains emerge. Vaxcyte's advancement of a 31-valent candidate represents a technical leap in valency that could shift the competitive dynamics of the adult vaccine market.

Vaxcyte, Inc. · financial snapshot

Share price	$56.48
Market cap	$8.4B
1-month price change	-7.12%
Sector	HealthcareBiotechnology

Reference market data from a third-party provider, as of the story. Not a valuation or a recommendation.