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. 2021 Aug;42(8):853-861.
doi: 10.15537/smj.2021.42.8.20210238.

Risk factors and predictors that influence SARS-Cov-2 IgG positivity: A cross-sectional study of blood donors in Riyadh, Saudi Arabia

Mohammed F Alosaimi  1 , Abdulkarim Alhetheel  1 , Khalid A Aleisa  1 , Abdullah A Altwerki  1 , Njoud M Alenezy  1 , Ebtisam M Almutairi  1 , Leen O Alothaim  1 , Abdul Manan A Khalid  1 , Khalid M Alayed  1 , Mohammed A Almazyad  1 , Turki A BinMoammar  1 , Fahdah A Alshobaili  1 , Fatimah S Al-Shahrani  1 , Sarah Alsubaie  1 , Rana M Hasanato  1
Affiliations

Risk factors and predictors that influence SARS-Cov-2 IgG positivity: A cross-sectional study of blood donors in Riyadh, Saudi Arabia

Mohammed F Alosaimi et al. Saudi Med J. 2021 Aug.

Abstract

Objectives: To study the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after pandemic's peak and before the vaccine enrollment in Riyadh, Saudi Arabia and further explore predictors for SARS-CoV-2 positivity.

Methods: A cross-sectional study of 515 blood donors from November 22 to December 17, 2020 was conducted at King Saud University Medical City, Riyadh, Saudi Arabia to look at SARS-CoV-2 immunoglobulin G (IgG) positivity. The participants were asked questions about their demographic characteristics, past SARS-CoV-2 infection, SARS-CoV-2-related symptoms and exposures.

Results: The seroprevalence in our study was 12.2% (n=63/515). Being a non-citizen was associated with significantly higher seroprevalence (OR 2.10, p=0.02). Participants with history of SARS-CoV-2 exposure or symptoms regardless of SARS-CoV-2 diagnosis had higher SARS-CoV-2 IgG positivity compared to unexposed or asymptomatic participants (OR 2.47, p=0.0008 or 11.19, p=0.0001, respectively). Blood donors who had symptomatic SARS-CoV-2 IgG infection had a higher SARS-CoV-2 IgG positivity rate (OR 5.04, p=0.008) and index value (p=0.003) than the asymptomatic. Of all the reported symptoms, cough (p=0.004) and anosmia (p=0.002) were significant predictors of SARS-CoV-2 IgG.

Conclusion: The seroprevalence of SARS-CoV-2 among the blood donors in Riyadh, Saudi Arabia is considerably lower than the percentages necessary for herd immunity. Developing SARS-CoV-2-symptoms is the critical factor for higher seropositivity after SARS-CoV-2 exposure.

Keywords: COVID-19; COVID-19 serological testing; SARS-CoV-2; Saudi Arabia; anosmia; blood donors; seroepidemiologic studies.

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Figures

Figure 1
Figure 1
- Epidemic timeline of severe acute respiratory syndrome coronavirus-2 positive cases in Saudi Arabia. Gray area reflects the timing of enrollment to the study. Pfizer-BioNTech vaccines were introduce on December 17, 2020 in Saudi Arabia. Data from Saudi Ministry of Health, Covid-19 Command and Control Center CCC (https://covid19.moh.gov.sa).
Figure 2
Figure 2
- Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) related risk factors for seropositivity. A) Seropositivity percentages of different time points from participants who had SARS-CoV-2 disease. B) SARS-CoV-2 IgG index value across different time points from participants who had SARS-CoV-2 disease. C) Seropositivity percentages of different time points from participants who had SARS-CoV-2 exposure. D) SARS-CoV-2 IgG index value across different time points from participants who had SARS-CoV-2 exposure. E) Comparing seropositivity percentages of controls (non-exposed and non-infected) with participants who had exposure to SARS-CoV-2 or had been infected with it. F) SARS-CoV-2 IgG index of symptomatic vs. asymptomatic SARS-CoV-2 infected participants. Bars in E represent frequency and Chi-squared test were used, bars in F represents mean, and 95% CI and t-test were used.
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