Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 11, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Registrant Name	VAXCYTE, INC.
Entity Central Index Key	0001649094
Current Fiscal Year End Date	--12-31
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity File Number	001-39323
Entity Tax Identification Number	46-4233385
Entity Address, Address Line One	353 Hatch Drive
Entity Address, City or Town	Foster City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94404
City Area Code	650
Local Phone Number	837-0111
Document Quarterly Report	true
Document Transition Report	false
Entity Small Business	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		50,949,711
Entity Filer Category	Non-accelerated Filer
Entity Interactive Data Current	Yes
Entity Current Reporting Status	No
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	PCVX
Security Exchange Name	NASDAQ