Authors’ contributions: All authors provided critical feedback on the manuscript.
Sibylle Bernard Stoecklin, Bruno Coignard and Daniel Levy-Bruhl wrote the manuscript with input from all authors.
Sibylle Bernard Stoecklin, Patrick Rolland, Alexandra Mailles, Christine Campese, Didier Che, Clément Lazarus, Anouk Tabaï, Morgane Stempfelet, Bruno Coignard and Daniel Levy-Bruhl contributed to the design and implementation of the surveillance system, as well as the coordination between all parties involved in the surveillance.
Patrick Rolland, Yassoungo Silue, Alexandra Mailles, Christine Campese, Anne Simondon, Matthieu Mechain, Laure Meurice, Mathieu Nguyen, Clément Bassi, Estelle Yamani, Scarlett Georges, as well as all members of the investigation team contributed to the investigations and the active surveillance of contacts.
Sophie Ismael, Duc Nguyen, Denis Malvy and François Xavier Lescure are the clinicians in charge of the three 2019-nCoV cases and contributed to data collection on clinical history, exposure and contacts.
Sylvie Behillil and Vincent Enouf contributed to the laboratory confirmation of 2019-nCoV infection in the three imported cases, as well as the testing of samples of possible cases.