Company Organization and Nature of Business - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended			6 Months Ended
	Jun. 15, 2020 shares	Jun. 05, 2020	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2020 $ / shares shares	Mar. 31, 2020 shares	Jun. 30, 2019 shares	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2019 shares	Jun. 17, 2020 shares	Dec. 31, 2019 shares
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]
Reverse stock split							one-for-1.6870
Reverse stock split, conversion ratio		0.593
Exercise of stock options (in shares)				152,177		889	195,834	889
Net proceeds from initial public offering | $			$ 264,100				$ 267,375
Underwriting discounts and commissions | $			20,100
Offering expenses | $			$ 3,300				$ 3,296
Redeemable convertible preferred stock, shares outstanding										20,390,095
Redeemable Convertible Preferred Stock
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of preferred stock (in shares)			28,610,337
Redeemable convertible preferred stock, shares outstanding			0	0			0		0
Common Stock
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]
Shares issued and sold				17,968,750
Exercise of stock options (in shares)				152,177	28,837	889
Conversion of preferred stock (in shares)	28,610,337			28,610,337
Initial Public Offering
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]
Shares issued and sold			17,968,750
Exercise of stock options (in shares)			2,343,750
Public offering price per share | $ / shares			$ 16.00	$ 16.00			$ 16.00
Pneumococcal Conjugate Vaccine
Schedule Of Organization Consolidation And Presentation Of Financial Statements [Line Items]
Global target revenue | $							$ 7,000,000