This communication may be deemed to be solicitation material in respect of SAIF Partners' nomination of ten director nominees to Sinovac's Board. In connection with such solicitation, SAIF Partners mailed the definitive proxy statement and proxy card to shareholders of Sinovac with respect to the Special Meeting to be held in connection with the election of directors to Sinovac's Board. The definitive proxy statement mailed by SAIF Partners is also filed as Exhibit 1 to its Schedule 13D/A filed on or about June 16, 2025. SHAREHOLDERS ARE URGED TO READ THE PROXY STATEMENT (INCLUDING ANY AMENDMENTS OR SUPPLEMENTS THERETO) AND ANY OTHER RELEVANT DOCUMENTS THAT THE COMPANY WILL MAIL AND FILE WITH THE SEC IN CONNECTION WITH THE SINOVAC SPECIAL MEETING, INCLUDING ANY DOCUMENT INCORPORATED BY REFERENCE THEREIN, CAREFULLY IF AND WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE DIRECTOR NOMINEES AND THE SPECIAL MEETING AND RELATED MATTERS.