[IMPORTANT REMINDER July 1, 2010 Dear Shareholder: We have previously mailed to you proxy materials relating to the Annual Meeting of Shareholders scheduled to be held on Thursday, July 15, 2010. According to our latest records, we have not received your proxy card for this important meeting. Regardless of the number of shares you own, it is important that they] [IMPORTANT ANNUAL MEEING IS SCHEDULED FOR JULY 15, 2010 PLEASE INSTRUCT YOUR BROKER TO VOTE TODAY! July 1, 2010 Dear Fellow Shareholder: Your vote is extremely important, regardless of the number of shares that you own. Please instruct your broker how to vote your shares today to avoid additional solicitation costs. According to our latest records, your broker has not] [1 -32371 SINOVAC BIOTECH LTD. No. 39 Shangdi Xi Road Haidian District Beijing 100085, People’s Republic of China Form 20-F x Form 40-F o o o SINOVAC BIOTECH LTD.]