Seroprevalence of SARS-CoV-2 in Healthy Blood Donors
Updated July 1, 2020
The Minnesota Department of Health (MDH) received test results for 983 blood donors whose plasma was tested for antibodies against SARS-CoV-2. Samples were collected during June 8-20, 2020 and came from 566 individuals (58%) from the Twin Cities metro area and 417 individuals (42%) from central and northeastern Minnesota, including Carlton, Chisago, Crow Wing, Hubbard, Isanti, Itasca, Lake, Pine, Sherburne, St. Louis, Stevens, and Wright Counties.
Innovative Blood Resources collected leftover plasma samples from blood donors who had made donations at Memorial Blood Center sites in the Twin Cities metro area and northeastern Minnesota. Innovative Blood Resources sent MDH de-identified demographic information, including donor age, sex, and zip code. De-identified samples were sent to the Advanced Research and Diagnostic Laboratory (ARDL) at the University of Minnesota. ARDL performed qualitative total immunoglobulins screens on the samples, which detect IgM, IgA, and IgG antibodies.
Of the 983 people tested, 12 (1.2%, 95% CI [0.6, 2.1]) tested positive for SARS-CoV-2 antibodies. Thirteen had equivocal results; 958 were negative for antibodies.
- 6 of 566 people (1.1%, 95% CI [0.4, 2.3]) from the metro area tested positive for antibodies.
- 6 of 417 people (1.4%, 95% CI [0.5, 3.1]) from greater Minnesota tested positive for antibodies.
- Blood donors included in the analysis were 16-86 years of age (mean age 52.7 years).
- People who tested positive were 33-78 years of age; mean age 54.9 years.
- 96% of donors included in the analysis identified as Caucasian/White.
- 9 (82%) of the 12 people who tested positive for antibodies identified as Caucasian/White. The remaining 3 people identified as other races, preferred not to disclose that information, or were missing race/ethnicity data.
- 49% of blood donors identified as male; 51% of donors identified as female.
- Of those who tested positive, 5 (42%) were male and 7 (58%) were female.
While blood donors are not representative of all Minnesotans, they do represent a subset of healthy adults. The seroprevalence of antibodies against SARS-CoV-2 was low in this population. There was no statistical difference between the proportion of donors who tested positive in the metro area and greater Minnesota. As of June 20, 2020, 32,920 people (0.6% of the Minnesota population) had had a positive PCR test for SARS-CoV-2.
This study will be repeated in the fall of 2020 to examine changes in seroprevalence over time.
Data were updated on July 1, 2020. At the time of the initial analysis, demographics were missing for 11 blood donors. Those data were updated and ten of the donors were determined not to live in Minnesota and were therefore excluded from the analysis.