The pairing induces a strong immune response and protection against SARS-CoV-2 in animal models, according to the firm. Rhesus macaques that received the vaccine were protected against SARS-CoV-2 infection, as demonstrated by clinical observations (protection from weight loss and increases in body temperature) and significant reduction in viral loads in lung tissues and swabs, with no signs of disease enhancement, the firm said. Also, the vaccine produced a Th1-polarized T-cell response in mice, rats, and monkeys.

The positive preclinical data supports Clover's decision to progress adjuvanted vaccine candidates using both adjuvants into the firm's ongoing phase I clinical study of S-Trimer, which started in June. The study has completed its enrollment of 150 adult and elderly participants. Based on preliminary results, Clover is enrolling an additional 200 participants in a phase I dose-expansion study. The firm also intends to initiate a global phase II/III vaccine efficacy study before the end of the year.

Clover's clinical trials are supported by funding and collaboration with the Coalition for Epidemic Preparedness Innovations (CEPI).