Dramatic rise in seroprevalence rates of SARS-CoV-2 antibodies among healthy blood donors: The evolution of a pandemic

Background: Seroprevalence studies of SARS-CoV-2 antibodies are useful in assessing the epidemiological status in the community, and the degree of spread.

Objective: To study the seroprevalence rates of SARS-CoV-2 antibodies among healthy blood donors in Jordan, at various points of time and as the pandemic evolves in the community.

Methods: In total, 1374 blood donor samples, from three groups, were tested for SARS-CoV-2 total immunoglobulin antibodies. In the first group, samples from 734 individuals (from donations made between January and June 2020) were tested in June. In the second group, 348 individuals were tested in September 2020. The third group of 292 individuals was tested in February 2021. A qualitative assay was used for testing (specificity 99.8%, sensitivity 100%).

Results: The first two groups, from January-June and September 2020, when confirmed Covid-19 cases numbered between several hundred and 3000, showed a seroprevalence rate of 0% (95% CI 0.00-0.51%). The third group (early February 2021), when the number of confirmed cases had reached 100 times that of September 2020, revealed a seroprevalence of 27.4% (95% CI 22.5-32.9%).

Conclusions: A dramatic rise in seroprevalence of SARS-CoV-2 antibodies was seen among healthy blood donors in Jordan, in parallel with widespread intracommunity transmission of the disease. This information is useful for assessing the degree of herd immunity, and provides for better understanding of the pandemic.