Fig. 4

Antibody levels in vaccinated naïve and vaccinated previously infected individuals according to DiaSorin and micro-neutralisation assays. a, b Observed antibody levels measured by DiaSorin assays in vaccinated naïve and previously infected individuals with at least one dose of vaccine (Mann-Whitney test, P < 0.0001) and with one or two doses of vaccine (Kruskal-Wallis test followed by Dunn’s multiple comparisons test, vaccinated naïve versus previously infected subjects after one vaccine dose, P < 0.0001; after two vaccine doses, P = 0.01; vaccinated naïve HCW versus previously infected subjects after two vaccine doses, P < 0.0001). c, d Observed neutralising antibody titres measured by a micro-neutralisation assay in vaccinated naïve and previously infected individuals with at least one dose of vaccine (Mann-Whitney test, P < 0.0001) and with one or two doses of vaccine (Kruskal-Wallis test followed by Dunn’s multiple comparisons test, vaccinated naïve versus previously infected subjects after one or two vaccine doses, P < 0.0001; vaccinated naïve HCW versus previously infected subjects after two vaccine doses, P < 0.0001). Asterisks indicate *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. HCW: healthcare workers. Previous infection is defined according to the ground truth definition provided in the text