CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities:
Net loss	$ (240,695)	$ (100,864)
Reconciliation of net loss to net cash used in operating activities:
Depreciation and amortization	3,091	4,744
Loss on disposal of property and equipment		88
Gain on Catalent transaction		(9,016)
Amortization of debt issuance costs	1,068	1,068
Non-cash stock-based compensation	77,602	12,803
Write off of right-of-use assets	187,193
Other	(4,119)	1,269
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(78,788)	1,326
Accounts payable and accrued expenses	60,540	(16,882)
Deferred revenue	80,135	(7,416)
Net cash provided by (used in) operating activities	86,027	(112,880)
Investing Activities:
Capital expenditures	(12,610)	(1,641)
Acquisition of Novavax CZ, net of cash acquired	(164,204)
Proceeds from Catalent transaction		18,333
Purchases of marketable securities	(266,330)	(17,484)
Proceeds from maturities of marketable securities	96,488	39,500
Net cash (used in) provided by investing activities	(346,656)	38,708
Financing Activities:
Net proceeds from sale of preferred stock	199,822
Net proceeds from sales of common stock	447,070	67,220
Proceeds from the exercise of stock based awards and incentive programs	35,708	992
Treasury stock related to tax withholding on stock-based awards	(37,024)
Finance lease payments	(65,424)
Net cash provided by financing activities	580,152	68,212
Effect of exchange rate on cash, cash equivalents and restricted cash	33	(69)
Net increase (decrease) in cash, cash equivalents and restricted cash	319,556	(6,029)
Cash, cash equivalents and restricted cash at beginning of period	82,180	81,959
Cash, cash equivalents and restricted cash at end of period	401,736	75,930
Supplemental disclosure of non-cash activities:
Sale of common stock under the Sales Agreement not settled at quarter-end	3,883	610
Capital expenditures included in accounts payable and accrued expenses	6,189	183
Right-of-use assets from new lease agreements	188,362
Supplemental disclosure of cash flow information:
Cash interest payments	$ 12,188	$ 12,188