Sinovac Biotech Ltd. announced that the Company has completed the phase I clinical trial for its broad-spectrum neutralizing antibody product, the Anti-COVID-19 Antibody SA55 Injection ("SA55 Injection") in Beijing and has entered the phase II clinical trial in Shanghai after successfully enrolling its first participant recently. SINOVAC's SA55 Injection, which is intended for the treatment of COVID-19 infections, was approved for clinical trial in China on May 24, 2023. The phase I clinical trial has confirmed its preliminary safety profile in 40 healthy adults aged 18 to 65 in China.

The phase II clinical trial is a multicenter, randomized, double-blind, placebo-controlled study. It is expected to enroll 150 patients aged 18 and above with mild to moderate COVID-19 infection from nearly 20 medical institutions in China. Participants will be randomly assigned to groups receiving different dosages of SA55 Injection or placebo to evaluate its ability to decrease SARS-CoV-2 virus loads and alleviate clinical symptoms, while assessing its safety.

Preliminary results are anticipated by the year's end. The broad- prospectrum neutralizing antibody SA55 was founded by a research team led by Dr. Xiaoliang Xie, academician of the Chinese Academy of Sciences and Dr. Yunlong Cao, researcher at Peking University's Biomedical Pioneering Innovation Center. SA55 injection is a fully humanized antibody, which is screened from the blood of recovered SARS patients who have received three doses of COVID-19 vaccine, and then recombinantly expressed, according to Dr. Xie.

Monoclonal neutralizing antibodies for COVID-19 serve as both treatment and prevention. As a treatment option, their good safety profile and fewer contraindications cater to a broader population than small-molecule drugs for COVID-19. As a prevention option, they have the advantage of rapidly increasing antibody levels post-administration and enjoy a longer half-life, making them suitable for immunocompromised individuals and those who would otherwise be ineligible for vaccination.

China's National Medical Products Administration has approved SINOVAC's SA 55 Nasal Spray for clinical trial in the prevention of COVID-19 infections.