Background: Covid-19 seroprevalence rates and serological tests are important tools in understanding the epidemiology of the disease and help in the fight against it. Seroprevalence rates vary according to the population studied and the test employed and they range from 0.133 to 25.7%. The purpose of this study is to assess the seroprevalence rate in a population of healthy blood donors living under strict lockdown measures in Jordan which has in total 71 confirmed cases per million population. Methods: Left over sera and plasma samples from 746 healthy blood donors were tested using a commercially available FDA approved kit having a specificity of 100%. External positive controls were used for validation. Results: More than 80% of the donors were men 18-63 year old and residing in the capital city of Jordan, Amman. All tested specimens were negative yielding a zero seroprevalence rate in this healthy blood donor population. Conclusion: Strict lockdown measures effectively limit intracommunity spread of the infection, however at the cost of lack of any acquired community immunity. Additionally the use of highly specific test is recommended in low prevalence setting.

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 as the pandemic evolves in the community. Methods A total of 1374 blood donor were tested for the SARS-CoV-2 total immunoglobulin antibodies in 3 groups. The first and second group: 746 and 348 individuals were tested in June and September-2020 respectively. The 3 rd group of 292 were tested in February-2021. We utilized a qualitative assay (specificity: 99.8%, sensitivity: 100%). Results The first 2 groups (January-September, 2020) when the number of confirmed Covid-19 cases were several hundred-3000 showed a seroprevalence rate of 0% (95% CI 0.00%-0.51%). The 3 rd group (early February 2021), when the number reported confirmed case has reached 100 folds 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 wide-spread intracommunity transmission of the disease. This information is useful to assess the degree of herd immunity and provides for better understanding of the pandemic.

Background: The coronavirus disease 2019 (COVID-19) pandemic has resulted in more than 106 million cases of confirmed infection and more than 2.3 million deaths worldwide as of February 11th 2021. Seroprevalence studies are extremely useful in studying and assessing the epidemiological status in the community and the degree of spread. They help decision makers in implementing or relaxing mitigating measures to contain the disease in addition to other benefits. Objective: To study the seroprevalence rates of SARS-CoV-2 antibodies among healthy blood donors in Jordan, at various points of time as the pandemic evolves in the community. Methods: A total of 1374 blood donor were tested for the SARS-CoV-2 antibodies in 3 groups. The first group of 746 and the second of 348 individuals were tested in June and September of 2020 respectively. The 3rd group of 292 were tested in early February of 2021. We utilized a qualitative assay that uses Electrochemiluminescence method (ECLIA) that has a specificity and sensitivity of 99.8% and 100% respectively. Results: The first 2 groups representing the months of January to September of 2020, where the number of confirmed Covid-19 cases were several hundred to 3000 showed a seroprevalence rate of 0% (95% CI 0.00%, 0.51%). The 3rd group representing late January and early February 2021 when the number of reported confirmed case has reached 100 folds the numbers of September 2020, showed a seroprevalence of 27.4% (95% CI 22.5% and 32.9%). Conclusions: a dramatic rise in seroprevalence of SARS-CoV-2 antibodies was seen among healthy blood donors in Jordan in parallel with wide-spread intracommunity transmission of the disease. This information is useful to assess the degree of herd immunity and provides for better understanding of the pandemic.

Objectives: To determine the impact of the second wave of COVID-19 and the vaccination campaign on the seroprevalence rates of SARS-CoV-2 antibodies among healthy blood donors in Jordan. Methods: Sera from 536 healthy adult blood donors collected in June -2021 were tested using a commercially available quantitative assay for the total antibodies including IgG against the spike (S) protein receptor binding domain (RBD) of the SARS-CoV-2. Results: 399 (74.4%) of the donors tested positive for the antibodies of whom 69 (17.3%) were confirmed to have been previously infected, 245(61.4%) have received at least one dose of the vaccine and 123(30.8%) were neither diagnosed nor vaccinated. The seropositive donors were significantly more likely to have been vaccinated or previously infected. Conclusion: The crude seroprevalence rate of 74.4% among this group of healthy donors may be encouraging in terms of approaching herd immunity, however with predominance of the delta variant and the uncertainty regarding the required level of herd immunity this goal appears to be far from full achievement in Jordan.

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