Nationwide Seroprevalence of SARS-CoV-2 in Saudi Arabia

Abstract

Background Estimated seroprevalence of Coronavirus Infectious Disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) is a critical evidence for a better evaluation of the virus spread and monitoring the progress of COVID-19 pandemic in a population. In the Kingdom of Saudi Arabia (KSA), SARS-CoV-2 seroprevalence has been reported in specific regions, but an extensive nationwide study has not been reported. Here, we report a nationwide study to determine the prevalence of SARS-CoV-2 in the population of KSA during the pandemic, using serum samples from healthy blood donors, non-COVID patients and healthcare workers (HCWs) in six different regions of the kingdom, with addition samples from COVID-19 patients. Methods A total of 11,703 serum samples were collected from different regions of the KSA including; 5395 samples from residual healthy blood donors (D); 5877 samples from non-COVID patients collected through residual sera at clinical biochemistry labs from non-COVID patients (P); and 400 samples from consented HCWs. To determine the seroprevalence of SARS-CoV-2, all serum samples, in addition to positive control sera from RT-PCR confirmed COVID-19 patients, were subjected to in-house ELISA with a sample pooling strategy, which was further validated by testing individual samples that make up some of the pools, with a statistical estimation method to report seroprevalence estimates. Results Overall (combining D and P groups) seroprevalence estimate was around 11% in Saudi Arabia; and was 5.1% (Riyadh), 1.5% (Jazan), 18.4% (Qassim), 20.8% (Hail), 14.7% (ER; Alahsa), and 18.8% in Makkah. Makkah samples were only D group and had a rate of 24.4% and 12.8% in the cities of Makkah and Jeddah, respectively. The seroprevalence in Saudi Arabia across the sampled areas would be 12 times the reported COVID-19 infection rate. Among HCWs, 7.5% (4.95–10.16 CI 95%) had reactive antibodies to SARS-CoV-2 without reporting any previously confirmed infection. This was higher in HCWs with hypertension. The study also presents the demographics and prevalence of co-morbidities in HCWs and subset of non-COVID-19 population. Interpretation Our study estimates the overall national serological prevalence of COVID-19 in Saudi Arabia to be 11%, with an apparent disparity between regions. This indicates the prevalence of asymptomatic or mild unreported COVID-19 cases.

Development of Serological Assays and Seroprevalence Studies of the New Coronavirus 2019 (COVID-19): Reports from Saudi Arabia

“…Importantly, the study period covered two months prior to reporting the first COVID-19 case in Saudi Arabia plus three months when the number of daily cases peaked in the country [ 5 ]. This study was supported by nationwide studies [ 39 , 41 ]. Indeed, the seroprevalence was as low as 1.4% among blood donors who were not diagnosed with COVID-19 during the first months of the pandemic [ 39 ].…”

“…In addition to healthcare workers, seroprevalence was investigated among blood donors and non-COVID-19 patients in order to estimate the seropositivity status among the general public [ 38 , 40 , 41 ]. The first study investigated this issue among all blood donors who attended a single-donation center from January to May 2020 [ 38 ].…”

SARS-CoV-2 seroprevalence among healthcare workers from a tertiary care center in Riyadh, Saudi Arabia

“…7 The correlation between seropositivity or antibody levels and protection against reinfection, as well as the life span of protective immunity in SARS-CoV-2 infection are critical for understanding pathophysiology and diagnosis of the disease. 8 Our study showed higher seroprevalence of antibodies against SARS-CoV-2 as compared to SARS-CoV-2 seroprevalence in Riyadh ... Albaadani et al 9 There is a large variation in the seroprevalence rate of SARS-CoV-2 in HCWs worldwide including Saudi Arabia. In fact, a wide global variation in seroprevalence ranging from 0.37% to 22.1% was observed in a meta-analysis carried out in August 2020, where the authors contributed such variation to the economical, geographical and the type of serological assay used in the study.…”

COVID-19 Infection in Academic Dental Hospital Personnel; A Cross-Sectional Survey in Saudi Arabia

“…Sample size determination was carried out using the epidemiological software: Epi Info™ (CDC, Centres for Disease Control, Atlanta, GA, USA) based on a population size of 316 (number of students and staff who consented to participate). The expected frequency (outcome probability) was assumed to be 7.5% based on serological prevalence of SARS-CoV-2 among healthcare workers in Saudi Arabia [7]. A sample size of 61 participants was determined to provide 90% confidence level at 5% margin of error.…”