Acknowledgements
The authors would like to thank the members of the ECDC Advisory Forum for reviewing the manuscript and providing pertinent comments. The authors would like to also thank all the ECDC staff that have contributed to the public health emergency response and indirectly contributed to the elaboration of this manuscript.

Conflict of interest: None declared.
Authors’ contributions: HCJ and CMG drafted the outline and the manuscript that were reviewed by all co-authors. All co-authors have provided substantial contribution to the design and the content of this manuscript. All co-authors approved the final version.