Table 1.
Main characteristics and outcomes of the sample, overall and by vaccine status.
| Overall Sample | ≥1 Vaccine Dose | Unvaccinated | ||
|---|---|---|---|---|
| Variables | (n = 245,226) | (n = 69,539) | (n = 175,687) | p * |
| Mean age in years (SD) | 53.2 (19.8) | 67.6 (16.7) | 47.5 (18.0) | <0.001 |
| Male gender, % | 47.9 | 43.1 | 49.7 | <0.001 |
| Priority category, % A | ||||
| - Elderly | 35.8 | 70.2 | 22.2 | <0.001 |
| - Fragile individuals | 2.5 | 8.7 | -- | -- |
| - School workers | 2.2 | 7.7 | -- | -- |
| - Healthcare workers | 1.9 | 6.9 | -- | -- |
| - Armed forces and civil operators | 1.1 | 4.1 | -- | -- |
| - Others | 0.7 | 2.4 | -- | -- |
| - Unknown | 55.7 | 0.0 | 77.8 | <0.001 |
| Risk factors and comorbidities B | ||||
| - Hypertension | 13.9 | 30.4 | 7.4 | <0.001 |
| - Diabetes | 5.8 | 12.6 | 3.1 | <0.001 |
| - Major cardio/cerebrovascular diseases | 7.1 | 15.2 | 3.8 | <0.001 |
| - COPD | 3.0 | 5.1 | 2.1 | <0.001 |
| - Kidney diseases | 1.9 | 3.5 | 1.3 | <0.001 |
| - Cancer | 5.0 | 10.3 | 3.0 | <0.001 |
| N. of vaccine doses, % C | ||||
| - One or two (n = 69,539) | 28.4 | 100.0 | -- | -- |
| - One only (n = 36,684) | 15.0 | 52.8 | -- | -- |
| - Two (n = 32,855) | 13.4 | 47.2 | -- | -- |
| Vaccine type-1st dose, % C | ||||
| - BNT162b2 (n = 47,654) | 19.4 | 68.5 | -- | -- |
| - ChAdOx1 nCoV-19 (n = 16,997) | 6.9 | 24.4 | -- | -- |
| - mRNA-1273 (n = 4888) | 2.0 | 7.0 | -- | -- |
| - None (n = 175,687) | 71.6 | -- | 100.0 | -- |
| Vaccine type-2nd dose D | ||||
| - BNT162b2 (n = 30,817) | 12.6 | 93.8 | -- | -- |
| - ChAdOx1 nCoV-19 (n = 18) | 0.0 | 0.1 | -- | -- |
| - mRNA-1273 (n = 2020) | 0.8 | 6.1 | -- | -- |
| - None (n = 212,371) | 86.6 | -- | 100.0 | -- |
| Average days between the start of the follow-up and SARS-CoV infection, (SD) E | 98 (43) | 38 (29) | 122 (17) | <0.001 |
| Average days between the start of the follow-up and COVID-19, (SD) F | 100 (42) | 38 (29) | 125 (6) | <0.001 |
| Average days between the start of the follow-up and death, (SD) G | 100 (42) | 38 (29) | 125 (3) | <0.001 |
| SARS-CoV-2 positive swab, % (n) D | 2.87 (7033) | 0.12 (85) | 4.00 (6948) | <0.001 |
| Covid-19 disease, % (n) D | 0.39 (951) | 0.03 (18) | 0.53 (933) | <0.001 |
| Death, % (n) D | 0.10 (244) | 0.00 (3) | 0.14 (241) | <0.001 |
* Chi-squared test for categorical variables, Kruskal–Wallis test for continuous ones. A The priority category, besides age, was not available for non-vaccinated subjects. Elderly—subjects aged ≥60 years; Fragile individuals—elderly in long-term care institutions, persons with a list of disabilities and chronic diseases defined by the Italian Government (the complete list is available at https://www.trovanorme.salute.gov.it/norme/renderPdf.spring?seriegu=SG&datagu=24/03/2021&redaz=21A01802&artp=1&art=1&subart=1&subart1=10&vers=1&prog=002 accessed on 9 June 2021; Healthcare workers—physicians and healthcare professionals; students of medicine and healthcare professions; long-term care facilities and clinical lab staff; School workers—all teachers from kindergarten to university; Armed forces and civil operators—policemen, firemen, military, civil protection operators; Others—people cohabiting with fragile individuals or SARS-CoV-2-infected subjects. B Subjects with the selected comorbidities in the Regional co-pay exemption database (Italian “Esenzioni Ticket” file) or an hospital admission in the last ten years (from the Italian SDO database of administrative discharge abstracts) with the following ICD-9-CM codes in any diagnosis field—250.xx (diabetes); 401.xx-405.xx (hypertension); 410.xx-412.xx or 414.xx-415.xx or 428.xx or 433.xx-436.xx (major cardiovascular or cerebrovascular diseases); 491.xx-493.xx (chronic obstructive pulmonary disease—COPD); 580.xx-589.xx (kidney diseases); 140.xx-172.xx or 174.xx-208.xx (cancers). C Administered at least 14 (BNT162b2 and mRNA-1273) or 21 (ChAdOx1 nCoV-19) days before the end of follow-up (21 May 2021). D After 14 (BNT162b2 and mRNA-1273) or 21 (ChAdOx1 nCoV-19) days from the administration of the first dose for the vaccinated subjects, and after 16 January 2021 for the unvaccinated subjects. E From the start of the follow-up to the first SARS-CoV-2-positive swab or the end of follow-up (21 May 2021). F From the start of the follow-up to the date of diagnosis of COVID-19 (confirmed with at least one SARS-CoV-2-positive swab), or the end of follow-up (21 May 2021). G From the start of the follow-up to in-hospital death (only subjects with at least one SARS-CoV-2 positive swab), or the end of follow-up (21 May 2021).