Funding for this research was provided by:
Ministero della Salute
World Health Organization
Received: 11 July 2018
Accepted: 5 September 2019
First Online: 1 November 2019
Ethics approval and consent to participate
: Ethics approval for the PASSI surveillance was granted by the Ethical Committee of the Istituto Superiore della Sanità (Italian National Institute of Health).
: Not applicable.
: The authors declare that they have no competing interests.