Seroprevalence of neutralizing antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers in Makkah, Saudi Arabia

Waleed A Ahmed; Ashraf Dada; Abeer N Alshukairi; Sayed S Sohrab; Arwa A Faizo; Ahmed M Tolah; Sherif A El-Kafrawy; Leena H Bajrai; Hanan M Moalim; Mohamed H Aly; Ahmed F Aboelazm; Mohammed A Al-Hamzi; Mohammed F Saeedi; Thamir A Alandijany; Esam I Azhar

doi:10.1016/j.jksus.2021.101366

Seroprevalence of neutralizing antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers in Makkah, Saudi Arabia

J King Saud Univ Sci. 2021 May;33(3):101366. doi: 10.1016/j.jksus.2021.101366. Epub 2021 Feb 13.

Authors

Waleed A Ahmed¹, Ashraf Dada², Abeer N Alshukairi³, Sayed S Sohrab^{4

5}, Arwa A Faizo^{4

5}, Ahmed M Tolah⁴, Sherif A El-Kafrawy^{4

5}, Leena H Bajrai^{4

6}, Hanan M Moalim¹, Mohamed H Aly¹, Ahmed F Aboelazm⁷, Mohammed A Al-Hamzi³, Mohammed F Saeedi³, Thamir A Alandijany^{4

5}, Esam I Azhar^{4

5}

Affiliations

¹ Department of Medicine, Security Forces Hospital, Makkah, Saudi Arabia.
² Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital & Research Center, Jeddah, Saudi Arabia.
³ Department of Medicine, King Faisal Specialist Hospital and Research Center, Jeddah, Saudi Arabia.
⁴ Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.
⁵ Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
⁶ Department of Biochemistry, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
⁷ Department of Infection Prevention and Control, Security Forces Hospital, Makkah, Saudi Arabia.

Abstract

Objective: The new coronavirus disease 2019 (COVID-19) is a major health problem worldwide. The surveillance of seropositive individuals serves as an indicator to the extent of infection spread and provides an estimation of herd immunity status among population. Reports from different countries investigated this issue among healthcare workers (HCWs) who are "at risk" and "sources of risk" for COVID-19. This study aims to investigate the seroprevalence of COVID-19 among HCWs in one of the COVID-19 referral centers in Makkah, Saudi Arabia using three different serological methods.

Methods: In-house developed enzyme-linked immunoassay (ELISA), commercially available electro-chemiluminescence immunoassay (ECLIA), and microneutralization (MN) assay were utilized to determine the seroprevalence rate among the study population. 204 HCWs participated in the study. Both physicians and nurses working in the COVID-19 and non COVID-19 areas were included. Twelve out of 204 were confirmed cases of COVID-19 with variable disease severity. Samples from recovered HCWs were collected four weeks post diagnosis.

Results: The overall seroprevalence rate was 6.3% (13 out of 204) using the in-house ELISA and MN assay and it was 5.8% (12 out of 204) using the commercial ECLIA. Among HCWs undiagnosed with COVID-19, the seroprevalence was 2% (4 out 192). Notably, neutralizing antibodies were not detected in 3 (25%) out 12 confirmed cases of COVID-19.

Conclusions: Our study, similar to the recent national multi-center study, showed a low seroprevalence of SARS-Cov-2 antibodies among HCWs. Concordance of results between the commercial electro-chemiluminescence immunoassay (ECLIA), in-house ELISA and MN assay was observed. The in-house ELISA is a promising tool for the serological diagnosis of SARS-CoV-2 infection. However, seroprevalence studies may underestimate the extent of COVID-19 infection as some cases with mild disease did not have detectable antibody responses.

Keywords: COVID-19; COVID-19, The new Coronavirus Disease 2019; DMEM-FCS, Dulbecco's Modified Eagle Medium containing fetal calf serum; ECLIA, Electro-chemiluminescence immunoassay; ELISA, Enzyme-linked immunoassay; HCL, 1N hydrochloric acid; HCWs, Healthcare Workers; Healthcare workers; MN, Microneutralization; OD450, Optical density at 450 nm; PBS, Phosphate Buffer Saline; PBST, PBS containing 0.1% Tween 20; SARS-CoV-2; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; SFH, Security Forces Hospital; Saudi Arabia; Seroprevalence; TCID50, Median Tissue Culture Infectious Dose; TMB, 3,3′,5,5′-Tetramethylbenzidine; WHO, World Health Organization.