Fig. 1.

Schematic depiction of the evolution of the pandemic. Dotted arrows indicate mutations, while the straight lines depict the slope of the exponential growth in log-space. The original ‘Wuhan’ variant was replaced by D614G, which has spawned in turn several successful variants with a higher reproductive number (R₀⁽¹⁾). This is the current evolution of the pandemic. Future developments (to the right of the red broken line) could include the emergence of more variants (‘X’, ‘Y’ etc.), with even greater reproductive numbers (R₀⁽²⁾, R₀⁽³⁾ etc.).