[Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report. 56,906,561 common shares as of December 31, 2015 ¨ x ¨ x x ¨ x ¨ o Large accelerated filer x Accelerated filer o Non-accelerated filer x U.S. GAAP International Financial] [List of Subsidiaries 1. Sinovac Biotech (Hong Kong) Ltd., a Hong Kong company 2. Sinovac Biotech Co., Ltd., a PRC company 3. Sinovac Research and Development Co., Ltd. (formerly known as Beijing Sinovac Biological Technology Co., Ltd.), a PRC company 4. Sinovac (Dalian) Vaccine Technology Co., Ltd., a PRC company 5. Sinovac Biomed Co., Ltd. (formerly known as Sinovac Zhong] [CERTIFICATION BY THE CHIEF EXECUTIVE OFFICER I, Weidong Yin, certify that: 1. I have reviewed this annual report on Form 20-F of Sinovac Biotech Ltd. (the “Company”); 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of] [CERTIFICATION BY THE CHIEF FINANCIAL OFFICER I, Nan Wang, certify that: 1. I have reviewed this annual report on Form 20-F of Sinovac Biotech Ltd. (the “Company”); 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of] [CERTIFICATION BY THE CHIEF EXECUTIVE OFFICER (1) (2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. Weidong Yin Chief Executive Officer] [CERTIFICATION BY THE CHIEF FINANCIAL OFFICER (1) (2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. Nan Wang Chief Financial Officer] [CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM We consent to the incorporation by reference in the following Registration Statements: i) Registration Statement (Form S-8 No. 333-161827) pertaining to Sinovac Biotech Ltd.’s 2003 Stock Option Plan; and ii) Registration Statement (Form S-8 No. 333-190980) pertaining to Sinovac Biotech Ltd.’s 2012 Share Incentive Plan; of our reports dated April 25, 2016, with]