**5. Conclusions**

In conclusion, the results of the present study demonstrate that infection rates based on surveillance data considerably underestimated the infection rates during the SARS-CoV-2 virus pandemic in Italy. The seroprevalence was much higher among people living in long-term care facilities or those with occupational exposure. In our opinion, these findings warrant further investigation into SARS-CoV-2 antibody prevalence among the Italian population.

**Author Contributions:** Conceptualization, M.B. (Marco Berruti) and M.B. (Matteo Bassetti); A.V.; methodology, A.V.; software, A.A.; P.B.; M.B. (Matteo Bassetti); R.C.; G.G.; D.R.G.; formal analysis, A.V. M.B. (Matteo Bassetti); investigation, A.A.; P.B.; M.B. (Matteo Bassetti); R.C.; G.G.; L.B.-L.; M.V.; N.V.; resources, A.A.; P.B.; M.B. (Michele Brignole); R.C.; G.G.; L.B.-L.; M.V.; N.V.; data curation, A.A.; P.B.; M.B. (Michele Brignole).; R.C.; G.G.; L.B.-L.; M.V.; N.V.; A.V.; writing—original draft preparation, A.V.; M.B. (Matteo Bassetti); writing—review and editing, A.V. P.P.; M.B. (Matteo Bassetti); L.T.; L.M.; I.B.; L.B.; C.R.; D.B. visualization, A.S.; supervision, M.B. (Matteo Bassetti); P.P.; funding acquisition A.A.; P.B.; M.B. (Michele Brignole); R.C.; G.G.; L.B.-L.; M.V.; N.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** Outside the submitted work, M.B. (Matteo Bassetti) has participated in advisory boards and/or received speaker honoraria from Achaogen, Angelini, Astellas, Bayer, Basilea, BioMeérieux, Cidara, Gilead, Menarini, MSD, Nabriva, Paratek, Pfizer, Roche, Melinta, Shionogi, Tetraphase, VenatoRx, and Vifor and has received study grants from Angelini, Basilea, Astellas, Shionogi, Cidara, Melinta, Gilead, Pfizer, and MSD. Outside the submitted work, D.R.G. reports honoraria from Stepstone Pharma GmbH and unconditional grants from MSD Italia and Correvio Italia. The authors declare no conflict of interest.
