• Advance B2 at 30ug into Phase 2/3 with 18-85YO

• Milder systemic reactogenicity profile of B2, primarily 65-85

• Comparable immune response elicited

• Lower reactogenicity (B2) may be due to the smaller size of the RNA constructs

• Note that immunogenicity decreased with age, yet still exceeded the base-line (GMT) of the convalescent serum panel

• Higer reactogenicity (B1) may be associated with an innate immune shut down of the host

• B2 (full length spike) present greater diversity.

• Limitations include: immunogenicity or safety beyond 7 days post dose-2 not available; uncertain importance of humoral and cellular immunity in protection from COVID-19; degree of protection against COVID also unknown.

• Plan to address limitation with a bigger sample size, and diverse backgrounds