Acknowledgements
We would like to thank all the authors who have kindly deposited and shared genomes on GSAID.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Author contributions
Conceptualization: Fabio Scarpa and Massimo Ciccozzi. Data Analyses: Fabio Scarpa. Writing-original draft preparation: Fabio Scarpa. Writing-review and editing: Fabio Scarpa, Daria Sanna, Marta Giovanetti, Stefano Pascarella, Marco Casu and Massimo Ciccozzi.