In response to the coronavirus disease 2019 (COVID-19), Saudi Arabia have imposed timely restrictions to minimize the infection spread, lower the risk for vulnerable groups, and reduce the pressure on healthcare services. The effectiveness of these measures has not been assessed comprehensively and, thereby, remains uncertain. Besides monitoring the number of COVID-19 cases diagnosed by molecular assays, the seroprevalence can serve as an indicator for the incidence rate among the general population. This study aimed to evaluate seroprevalence status of all healthy blood donors who attended one of the main largest hospital located in the western region of Saudi Arabia from 1 January to 31 May 2020. The study period covered two months prior to reporting the first COVID-19 case in the country on 2 March 2020. Importantly, it covered the period when “lock-down type” measures have been enforced. Samples were subjected to in-house enzyme-linked immunosorbent assay (ELISA), chemiluminescence immunoassay (CLIA), and microneutralization (MN). The sero statuses of all samples were confirmed negative, demonstrating the lack of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among blood donors during COVID-19 lockdown period. This study supports the hypothesis that COVID-19 restrictions have potential for limiting the extent of the infection.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has significantly impacted global public health and the economy. This study aimed to investigate the seroprevalence of IgG antibodies against SARS-CoV-2 among healthy blood donors in Jeddah, Saudi Arabia, to better understand the dynamics of COVID-19 transmission during three distinct periods: pre-lockdown, during-lockdown, and post-lockdown. The seroprevalence was assessed concerning demographic factors such as gender, age, blood group, and nationality. A cross-sectional study was conducted from December 2019 to December 2020. A total of 3,825 blood samples from healthy donors were screened using an in-house enzyme-linked immunosorbent assay (ELISA) for anti-SARS-CoV-2 IgG antibodies detection. Positive samples were further confirmed using a micro-neutralization (MN) assay. Of 3,825 serum samples, 173 (4.5%) were tested positive by ELISA, and 147 samples were confirmed positive by MN. All samples collected before the lockdown (December 2019 to February 2020) were negative for IgG antibodies. During the lockdown period (March 2020 to June 2020), 44 out of 1,482 samples (2.97%) were tested positive. After the lockdown was eased (July 2020 to December 2020), the positivity rate increased to 12.15% (103 out of 848 samples). The overall seroprevalence rate among healthy blood donors was 3.84%, with significantly higher rates among non-Saudi and male donors (p = 0.00). The findings suggest that COVID-19 restrictions implemented by the Saudi authorities were effective in reducing the initial spread of the virus. However, the marked increase in seroprevalence over time suggests that asymptomatic or mildly symptomatic individuals may pose a significant risk for continued transmission. Continuous monitoring of seroprevalence is essential to control the spread of COVID-19.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has significantly impacted global public health and the economy. This study aimed to investigate the seroprevalence of IgG antibodies against SARS-CoV-2 among healthy blood donors in Jeddah, Saudi Arabia, to better understand the dynamics of COVID-19 transmission during three distinct periods: pre-lockdown, during-lockdown, and post-lockdown. The seroprevalence was assessed concerning demographic factors such as gender, age, blood group, and nationality. A cross-sectional study was conducted from December 2019 to December 2020. A total of 3,825 blood samples from healthy donors were screened using an in-house enzyme-linked immunosorbent assay (ELISA) for anti-SARS-CoV-2 IgG antibodies detection. Positive samples were further confirmed using a micro-neutralization (MN) assay. Of 3,825 serum samples, 173 (4.5%) were tested positive by ELISA, and 147 samples were confirmed positive by MN. All samples collected before the lockdown (December 2019 to February 2020) were negative for IgG antibodies. During the lockdown period (March 2020 to June 2020), 44 out of 1,482 samples (2.97%) were tested positive. After the lockdown was eased (July 2020 to December 2020), the positivity rate increased to 12.15% (103 out of 848 samples). The overall seroprevalence rate among healthy blood donors was 3.84%, with significantly higher rates among non-Saudi and male donors (p = 0.00). The findings suggest that COVID-19 restrictions implemented by the Saudi authorities were effective in reducing the initial spread of the virus. However, the marked increase in seroprevalence over time suggests that asymptomatic or mildly symptomatic individuals may pose a significant risk for continued transmission. Continuous monitoring of seroprevalence is essential to control the spread of COVID-19.