Table 1. General guide to aid in determining the possible causes of antibody binding changes between spike variants.

Sequence comparison (variant vs. Wuhan-Hu-1)	Binding comparison (variant vs. Wuhan-Hu-1)	Cross-reactivity and epitope accessibility
No change	No change	Cross-reactive
No change	Significantly reduced, non-zero	Reduced epitope accessibility
No change	No binding	Severe or complete reduction in epitope accessibility
No change	Significantly improved	Cross-reactive, improved epitope accessibility
Mutation(s)	No change	Cross-reactive*
Mutation(s)	Significantly reduced, non-zero	Cross-reactive, potential loss of affinity*
Mutation(s)	No binding	Not cross-reactive*
Mutation(s)	Significantly improved	Cross-reactive*