Table 1.
Serological Status and Seroprevalence Among Danish Blood Donors by Region in Denmark
| Serological Status and Seroprevalence | Weeks 41 to 44, 2020 | Weeks 5 to 8, 2021 |
|---|---|---|
| SARS-CoV-2 serological status | ||
| Seronegative, n (%) | ||
| Capital | 6419 (29) | 5395 (29) |
| Central Denmark | 5255 (24) | 4919 (26) |
| North Denmark | 2361 (11) | 1991 (11) |
| South Denmark | 4905 (22) | 3825 (20) |
| Zealand | 3191 (14) | 2759 (15) |
| Total | 22131 (100) | 18889 (100) |
| Seropositive, n (%) | ||
| Capital | 288 (52) | 706 (47) |
| Central Denmark | 99 (18) | 317 (21) |
| North Denmark | 29 (5) | 118 (8) |
| South Denmark | 89 (16) | 161 (11) |
| Zealand | 54 (10) | 207 (14) |
| Total | 559 (100) | 1509 (100) |
| Donor seroprevalence | ||
| Unadjusted seroprevalence, % | ||
| Capital | 4.29 | 11.6 |
| Central Denmark | 1.85 | 6.05 |
| North Denmark | 1.21 | 5.60 |
| South Denmark | 1.78 | 4.04 |
| Zealand | 1.66 | 6.98 |
| Total | 2.46 | 7.40 |
| Adjusted seroprevalence, % (95% CI)a | ||
| Capital | 3.98 (2.99–4.61) | 11.6 (10.4–12.6) |
| Central Denmark | 1.44 (.48–1.95) | 5.81 (4.75–6.60) |
| North Denmark | 0.78 (.00–1.38) | 5.34 (4.06–6.47) |
| South Denmark | 1.37 (.41–1.88) | 3.72 (2.66–4.46) |
| Zealand | 1.25 (.27–1.83) | 6.77 (5.54–7.85) |
| Total | 2.08 (1.17–2.47) | 7.21 (6.30–7.78) |
Serological status and seroprevalence among Danish blood donors stratified by region for weeks 41 to 44, 2020 and weeks 5 to 8, 2021. The exact numbers stratified by region and age were used in the estimation of the number of SARS-CoV-2 seropositives. However, due to the low number of seropositives in specific age strata for some regions, only total numbers and seroprevalences per region are presented.
Abbreviations: CI, confidence interval; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Seroprevalence adjusted for assay sensitivity and specificity.