Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended	6 Months Ended		58 Months Ended
	May 31, 2020	Sep. 30, 2015	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Summary of Significant Accounting Policies [Line Items]
Number of shares excluded from the computation of net loss per share				7,797,651	2,935,847
Restricted cash current			$ 106,768	$ 106,768		$ 106,768	$ 2,947
Purchase price held in escrow			11,200	11,200		11,200
Foreign currency translation adjustment			$ 13,200	$ 13,200		$ 13,200	$ 12,500
Series A Convertible Preferred Stock
Summary of Significant Accounting Policies [Line Items]
Number of shares excluded from the computation of net loss per share				4,388,850
Preferred stock, shares outstanding			438,885	438,885		438,885
Catalent Maryland, Inc
Summary of Significant Accounting Policies [Line Items]
Purchase price held in escrow			$ 1,500	$ 1,500		$ 1,500
Bill Melinda Gates Foundation [Member]
Summary of Significant Accounting Policies [Line Items]
Grant Agreement		$ 89,100
Grant revenue recognized						82,000
Coalition for Epidemic Preparedness Innovations
Summary of Significant Accounting Policies [Line Items]
Restricted cash current			92,600	92,600		92,600
Initial Funding Development Costs	$ 384,500			388,400
Grant Funding
Summary of Significant Accounting Policies [Line Items]
Initial Funding Development Costs	245,900			245,900
Revenue recognized			34,200	36,500
Forgivable Loan Funding
Summary of Significant Accounting Policies [Line Items]
Initial Funding Development Costs	$ 142,500			142,500
Proceeds from funding agreement			76,000	$ 76,000		76,000
Convertible Debt Securities [Member]
Summary of Significant Accounting Policies [Line Items]
Number of shares excluded from the computation of net loss per share				2,385,800
Convertible Notes Initial Conversion Price Per Share				$ 136.20
Security Deposit [Member]
Summary of Significant Accounting Policies [Line Items]
Purchase price held in escrow			400	$ 400		400
Grant Agreement [Member]
Summary of Significant Accounting Policies [Line Items]
Restricted cash current			$ 1,400	$ 1,400		$ 1,400