Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (146,696)	$ (173,771)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Share-based compensation	30,324	21,746
Depreciation	1,062	686
Non-cash interest expense	1,818	40
Foreign currency transaction gain	0	(16,178)
Amortization of operating lease right-of-use assets	1,250	1,101
Other	9	538
Changes in operating assets and liabilities:
Accounts receivable	(15,340)	0
Inventories	(4,126)	0
Prepaid expenses and other current assets	(7,259)	89
Amount due from related party	(550)	0
Other assets	(3,641)	(1,309)
Accounts payable	(5,679)	(2,977)
Interest payable (related party)	0	(15)
Accrued expenses and other current liabilities	13,811	15,317
Deferred revenue	3,480	478,908
Amounts due to Pfizer	35,773	0
Cost share advance from Pfizer	(68,654)	138,800
Operating lease liabilities	(1,326)	(1,112)
Amounts due to related parties	(152)	628
Other liabilities	(2,576)	1,080
Net cash (used in) provided by operating activities	(168,472)	463,571
Cash flows from investing activities:
Purchases of marketable securities	(118,837)	(47,562)
Maturities of marketable securities	59,252	18,235
Purchases of property and equipment	(723)	(1,036)
Net cash used in investing activities	(60,308)	(30,363)
Cash flows from financing activities:
Capital contribution- other	1,280	0
Proceeds from related party debt financing	0	200,000
Proceeds from stock option exercises	17,862	5,284
Net cash provided by financing activities	19,142	205,284
Net change in cash, cash equivalents and restricted cash	(209,638)	638,492
Cash, cash equivalents and restricted cash, beginning of period	677,480	78,018
Cash, cash equivalents and restricted cash, end of period	467,842	716,510
Supplemental Disclosures of Non-Cash Financing Information:
Change in fair value of share-based awards recorded to additional paid-in capital	1,738	0
Reclassification of share-based compensation liabilities to additional paid-in capital upon settlement of awards	$ 20,650	$ 0