Phase I/II results described by one analyst as “stunning” put Vaxcyte Inc. in position for a phase III trial with VAX-31, the firm’s 31-valent pneumococcal conjugate vaccine candidate designed to prevent invasive disease. San Carlos, Calif.-based Vaxcyte’s shares (NASDAQ:PCVX) closed Sept. 3 at $110.15, up $29.39, or 36.4%, on positive top-line results from the study testing the safety, tolerability and immunogenicity of the product in 1,015 healthy adults ages 50 and older.