Scientist II, Upstream Development for Protein Development and Manufacturing

Join our Mission to Protect Humankind! Vaxcyte is a clinical-stage vaccine innovation company engineering high-fidelity vaccines to protect humankind from the consequences of bacterial diseases, which have serious and costly health consequences when left unchecked. Working to eradicate or treat bacterial infections such as invasive pneumococcal disease, Group A Strep, and Shigella is just the beginning. Our path to success is clear and well-defined, and Vaxcyte is set up to go the distance. WHAT we do is every bit as important as HOW we do it! Our work together is guided by four enduring core values: *RETHINK CONVENTION: We bring creative and intellectual diversity to every facet of the work we do in order to innovate and re-innovate the way vaccines are delivered. *AIM HIGH: We embody our collectively audacious goal to courageously make the most complex biologics ever attempted to protect humankind. *LEAD WITH HEART: Everyone leads at Vaxcyte with a kindness-first, inclusive approach to collaboration and vigorous debate that advances our business objectives. *MODEL EXCELLENCE: The magnitude of our challenge requires our shared commitment to demonstrating integrity, accountability, equality and clarity across communications and decision making. Summary: Vaxcyte is seeking a curious and scientifically rigorous Scientist II to join the Upstream Process Development group within the Protein Development and CMC organization. The successful candidate's primary responsibility will be to design and execute experimental programs that build a deeper mechanistic understanding of bacterial fermentation for the production of critical raw materials that support production of Vaxcyte's novel carrier proteins — how host physiology, media composition, feeding strategy, and bioreactor conditions together govern cell growth, protein expression, and product quality. This is a role for a scientist who is not satisfied with a process that works, but wants to understand why it works and where its limits are. The candidate will frame questions, design studies to answer them, analyze the resulting data with statistical rigor, and translate findings into process knowledge that supports scalability, robustness, and technical readiness for clinical and commercial manufacturing. Work spans the current pneumococcal conjugate vaccine program and earlier pipeline programs, and requires close intellectual partnership with Downstream Process Development, Analytical Development, MSAT, and Pilot Plant colleagues. Essential Functions: • Design and execute hypothesis-driven fermentation studies to establish how critical process parameters influence cell growth kinetics, protein expression, and product quality attributes. • Apply Design of Experiments and statistical analysis to characterize the process, identify critical and key process parameters, define proven acceptable ranges, and support establishment of the process design space. • Investigate unexpected or anomalous results – variability in growth, titer, or quality – through structured, root-cause experimentation. • Develop, qualify, and challenge scale-down models; assess their representativeness against pilot- and manufacturing-scale data and use them to predict performance at scale. • Design feeding strategies and control approaches for fed-batch fermentation, including recipe scripting on Ambr® 250 and benchtop systems, as a means of testing metabolic hypotheses and improving process robustness. • Evaluate and implement new experimental approaches, at-line or online monitoring, and analytical or data-analysis tools that increase the resolution with which the team can observe and interpret the process. Develop workflows beyond established procedures where existing methods are insufficient. •