Prime Success Responds to Sinovac Biotech’s False and Misleading Claims

Prime Success L.P., (together with its affiliates, “Prime Success” or “we”), a significant shareholder of Sinovac Biotech Ltd. (NASDAQ: SVA) (“Sinovac” or the “Company”) with ownership of approximately 8% of the Company’s outstanding shares, today issued the following letter in response to the Company’s recent false and misleading claims relating to the upcoming Special Meeting of Shareholders (the “Special Meeting”) scheduled for July 8, 2025.

The full text of the letter is below and available at www.SaveSinovac.com.

Dear fellow Sinovac shareholders,

Prime Success, L.P. (together with its affiliates, “Prime Success” or “we”), a significant shareholder of Sinovac Biotech Ltd. (NASDAQ: SVA) (“Sinovac” or the “Company”), continues to be disappointed by the current Board’s (“1Globe Activist Board”) distortion of the facts about what is at stake at the upcoming Special Meeting of Shareholders (the “Special Meeting”) scheduled for July 8, 2025. In our June 10 letter we addressed several of the 1Globe Activist Board’s misstatements and are taking the opportunity to remind all shareholders why the 1Globe Activist Board cannot be trusted:

1. Prime Success is insisting that a dividend be distributed – for all shareholders

The 1Globe Activist Board’s false comments are just not credible – why would any investor be against receiving a dividend? The 1Globe Activist Board wants you to believe that Prime Success is the reason that dividends have not been distributed, but we are not the Company and are not on the Board, and dividend distribution decisions are not ours to make. We can only continue to advocate on behalf of all shareholders that they should be made.

Under the leadership of a SAIF Partners IV L.P. (“SAIF”) nominated Board — composed of seasoned professionals with proven governance experience, deep operational insight, and a track record of building real, lasting value — we are confident that the pattern of internal conflict and ongoing litigation fueled by the 1Globe Activist Board can be broken, and shareholders can look forward to more future dividends. But that will not be possible with the 1Globe Activist Board in power as they have made clear they prioritize endless litigation over the Company’s long-term success.