The seroprevalence of SARS-CoV-2 IgG antibodies among asymptomatic blood donors in Saudi Arabia

BACKGROUND: In late 2019, cases of severe pneumonia with unidentified etiology began to emerge in Wuhan, China, before progressively spreading first nationally and then globally. The current study sought to investigate the seroprevalence of immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among blood donors in Al-Madinah, Saudi Arabia. To our knowledge, this is the first study in Saudi Arabia to screen blood donors who were not known to be previously infected with SARS-CoV-2. METHODS: This study was a cross-sectional study to assess individuals who donated blood to the central blood bank in Al-Madinah between mid-May and mid-July 2020. An enzyme-linked immunosorbent assay (ELISA) was designed and established to detect antibodies directed against the SARS-CoV-2 spike protein in serum samples. A total of 1,212 healthy blood donors participated in this study. The donors were males and met the requirements for blood donation during the COVID-19 pandemic period in Saudi Arabia. RESULTS: The SARS-CoV-2 seroprevalence among blood donors in Al-Madinah was 19.31% (n = 234/1212; 95% confidence interval: 17.12%–21.64%). No statistically significant difference was identified in seropositivity according to age. However, significant differences (p < 0.001) were identified according to ABO blood groups, with those with type A blood presenting the highest rate of seropositivity (29.18%) compared with the other blood groups (12.65% for type B, 16.36% for type AB, and 15.11% for type O). CONCLUSION: A high prevalence of SARS-CoV-2 antibodies was detected among blood donors in Al-Madinah, which indicated a high level of exposure to the virus within the population. This further suggested that as high as one-fifth of the population may have acquired innate immunity against the virus.