Healthcare policies, precautionary measures and outcomes of mass gathering events in the era of COVID-19 pandemic: Expedited review.

With the onset of the COVID-19 pandemic in early 2020, several countries suspended or restricted mass gathering (MG) events to mitigate the risk of superspreading events. Prohibiting MGs aimed to lessen the likelihood of highly infectious persons coming into close contact with many others. Now that the world has opened its doors wide and removed most of precautionary measures, many questions arise. In this review, we aimed to summarize the current evidence regarding the policies and regulations that were implemented for the safe return of MG events. Besides, we highlighted the impact of the return of MG events during 2021 on the trajectory of COVID-19 spread. Canceling MG events can carry religious, societal, economic, and public negative consequences necessitating the safe return of these events. The experience with the COVID-19 pandemic was the foundation for the recommendations for the safe conduction of MG events during the pandemic by international public health bodies. When policymakers adequately applied precautionary measures and strategic approaches, we witnessed the safe holding of huge MG events without aggravating the COVID-19 situation or increasing the number of new cases beyond the capacity and readiness of the national healthcare system.

Does ChAdOx1-S and BNT162b2 heterologous prime-boost vaccination trigger higher rates of vaccine-related adverse events?

Background: There has been significant international interest in heterologous prime-boost COVID-19 vaccination. However, it is linked with different intensity and frequency of adverse events. This study aimed to assess the safety of ChAdOx1-S and BNT162b2 vaccines when given as heterologous prime-boost vaccination in Saudi Arabia. Methods: A cross-sectional study was conducted during the period October 2021 to March 2022. The study included two groups of people based on the type of vaccination regimen. The first group (heterologous) was subjected to different prime-boost vaccination schedules irrespective of the prime and boost vaccine types. The second group included people vaccinated with the same type of COVID-19 vaccine (homologous). Results: The overall sample included 334 participants. Those included in the heterologous group were at about 1.5 fold -increased risk for developing local and systemic adverse events compared to the homologous group. Fever, headache, and vomiting were significantly more frequent among the heterologous group compared to the homologous group (p-value<0.05). In both groups, more than half of the recorded adverse events were mild/moderate in severity. Conclusion: Heterologous prime-post vaccination is associated with a slightly increased risk for the development of local and systemic adverse events compared to the homologous regimen. However, most of these adverse events are mild/moderate in nature and recede within two days with no serious adverse events documented.

Does ChAdOx1-S and BNT162b2 heterologous prime-boost vaccination trigger higher rates of vaccine-related adverse events?

Background There has been a significant international interest in heterologous prime-boost COVID-19 vaccination. However, it was linked with different intensity and frequency of adverse events. This study aimed to assess the safety of ChAdOx1-S and BNT162b2 vaccines when given as heterologous prime-boost vaccination in Saudi Arabia. Methods A cross-sectional study was conducted during the period October 2021 to March 2022. The study included two groups of people based on the type of vaccination regimen. The first group (heterologous) was subjected to different prime-boost vaccination schedules irrespective of the prime and boost vaccine types. While the second group included people vaccinated with the same type of COVID-19 vaccine (homologous). Results The overall sample included was 334 participants. Those included in the heterologous group were at about 1.5 fold -increased risk for developing local and systematic adverse events compared to homologous group. Fever, headache, and vomiting were significantly more frequent among heterologous group compared to homologous one (p-value<0.05). In both groups, more than half of the recorded adverse events were mild/moderate in severity. Conclusion Heterologous prime-post vaccination is associated with slightly increased risk for the development of local and systemic adverse events compared to the homologous regimen. However, most of these adverse events are mild/moderate in nature and recede within two days with no serious adverse events documented.

Healthcare Policies, Precautionary Measures and Outcomes of Mass Gathering Events in the Era of COVID-19 Pandemic: Expedited Review

With the onset of the COVID-19 pandemic in early 2020, several countries suspended or restricted mass gathering (MG) events to mitigate the risk of superspreading events. Prohibiting MGs aimed to lessen the likelihood of highly infectious persons coming into close contact with many others. Now that the world has opened its doors wide and removed most of precautionary measures, many questions arise. In this review, we aimed to summarize the current evidence regarding the policies and regulations that were implemented for the safe return of MG events. Besides, we highlighted the impact of the return of MG events during 2021 on the trajectory of COVID-19 spread. Canceling MG events can carry religious, societal, economic, and public negative consequences necessitating the safe return of these events. The experience with the COVID-19 pandemic was the foundation for the recommendations for the safe conduction of MG events during the pandemic by international public health bodies. When policymakers adequately applied precautionary measures and strategic approaches, we witnessed the safe holding of huge MG events without aggravating the COVID-19 situation or increasing the number of new cases beyond the capacity and readiness of the national healthcare system.

Bed Surge Capacity in Saudi Hospitals During the COVID-19 Pandemic.

OBJECTIVES: To assess the hospital beds and intensive care unit (ICU) beds with a ventilator surge capacity of the health system in Kingdom of Saudi Arabia (KSA) during the coronavirus disease (COVID-19) pandemic. METHODS: This study used relevant data from the National Health Emergency Operation Center to estimate general hospital and ICU bed surge capacity and tipping points under 3 distinct transmission scenarios. RESULTS: The study results reveal that hospitals in the KSA need to be supplied with additional 4372 hospital beds to care for COVID-19 positive cases if the pandemic continues over a 6 months' period. At the same time, it requires additional 2192 or 1461 hospital beds if the pandemic persists over a 12- or 18-month period, respectively, to manage hospitalized COVID-19 overloads. The health system surge capacity would suffer from a shortage of 1600, 797, and 540 ICU beds under the 3 transmission scenarios to absorb critical and intensive care COVID-19 cases. CONCLUSION: Our findings highlight the urgent need for additional hospital and ICU beds in the face of critical COVID-19 cases in KSA. The study recommends further assessment measures to the health system surge capacity to keep the Saudi health system prepared during the COVID-19 pandemic.

Type I interferon autoantibodies in hospitalized patients with Middle East respiratory syndrome and association with outcomes and treatment effect of interferon beta-1b in MIRACLE clinical trial.

Background: Type I interferons (IFNs) are essential antiviral cytokines induced upon respiratory exposure to coronaviruses. Defects in type I IFN signaling can result in severe disease upon exposure to respiratory viral infection and are associated with worse clinical outcomes. Neutralizing autoantibodies (auto-Abs) to type I IFNs were reported as a risk factor for life-threatening COVID-19, but their presence has not been evaluated in patients with severe Middle East respiratory syndrome (MERS). Methods: We evaluated the prevalence of type I IFN auto-Abs in a cohort of hospitalized patients with MERS who were enrolled in a placebo-controlled clinical trial for treatment with IFN-ß1b and lopinavir-ritonavir (MIRACLE trial). Samples were tested for type I IFN auto-Abs using a multiplex particle-based assay. Results: Among the 62 enrolled patients, 15 (24.2%) were positive for immunoglobulin G auto-Abs for at least one subtype of type I IFNs. Auto-Abs positive patients were not different from auto-Abs negative patients in age, sex, or comorbidities. However, the majority (93.3%) of patients who were auto-Abs positive were critically ill and admitted to the ICU at the time of enrollment compared to 66% in the auto-Abs negative patients. The effect of treatment with IFN-ß1b and lopinavir-ritonavir did not significantly differ between the two groups. Conclusion: This study demonstrates the presence of type I IFN auto-Abs in hospitalized patients with MERS.

Adverse events following administration of COVID-19 vaccines in Saudi Arabia.

Previous studies investigated the frequency of different adverse events of COVID-19 vaccines. However, this study compares these adverse events between the two main COVID-19 vaccines used in Saudi Arabia (Pfizer-BioNTech and Oxford-AstraZeneca) using telemedicine technology. A cross-sectional study was conducted among 958 individuals, 7 days after receiving either Pfizer-BioNTech or Oxford-AstraZeneca vaccines during June 2021. Immediate adverse events were reported by 1.04% and 2.09% for Pfizer-BioNTech and Oxford-AstraZeneca vaccines, respectively, with no serious events. Recipients of Pfizer-BioNTech vaccine had a higher percentage of local adverse events (24.8% versus 9.8% in AstraZeneca vaccine). The most common reported systemic adverse events in both vaccines respectively were general fatigue (23.1% and 25.1%), fever (18.5% and 27.2%), myalgia (20.6% and 20.3%), and headache (15.2% and 17.2%). No significant difference was recorded between both vaccines regarding overall systemic adverse events; however, they were more frequent following the first dose of AstraZeneca vaccine compared to Pfizer-BioNTech vaccine, while the reverse was observed for the second dose. Adverse events were more frequent in females and younger age groups for both vaccines. Most of systemic and local adverse events were mild in nature. Further cohort studies are recommended to investigate the long-term adverse events of COVID-19 vaccines.

Heterogeneity of treatment effect of interferon-ß1b and lopinavir-ritonavir in patients with Middle East respiratory syndrome by cytokine levels.

Animal and human data indicate variable effects of interferons in treating coronavirus infections according to inflammatory status and timing of therapy. In this sub-study of the MIRACLE trial (MERS-CoV Infection Treated with a Combination of Lopinavir-Ritonavir and Interferon ß-1b), we evaluated the heterogeneity of treatment effect of interferon-ß1b and lopinavir-ritonavir versus placebo among hospitalized patients with MERS on 90-day mortality, according to cytokine levels and timing of therapy. We measured plasma levels of 17 cytokines at enrollment and tested the treatment effect on 90-day mortality according to cytokine levels (higher versus lower levels using the upper tertile (67%) as a cutoff point) and time to treatment (≤ 7 days versus > 7 days of symptom onset) using interaction tests. Among 70 included patients, 32 received interferon-ß1b and lopinavir-ritonavir and 38 received placebo. Interferon-ß1b and lopinavir-ritonavir reduced mortality in patients with lower IL-2, IL-8 and IL-13 plasma concentrations but not in patients with higher levels (p-value for interaction = 0.09, 0.07, and 0.05, respectively) and with early but not late therapy (p = 0.002). There was no statistically significant heterogeneity of treatment effect according to other cytokine levels. Further work is needed to evaluate whether the assessment of inflammatory status can help in identifying patients with MERS who may benefit from interferon-ß1b and lopinavir-ritonavir. Trial registration: This is a sub-study of the MIRACLE trial (ClinicalTrials.gov number, NCT02845843).

Hajj 2021: Role of mitigation measures for health security.

PURPOSE: After the impressive results of the 2020 Hajj management, Saudi authorities decided to expand the quota to 60,000 pilgrims in 2021, which resulted in a convenient and successful experience. PATIENTS AND METHODS: This was a retrospective pre and post-study study conducted on all pilgrims attending the 2021 Hajj using the polymerase chain reaction (PCR) test surveillance with paired-swab samples (pre-Hajj and post-Hajj) to evaluate the risk potential of COVID-19 among Hajj pilgrims, the effectiveness of preventive measures and the potential effect of the Hajj ritual as a huge mass gathering on the epidemiological situation of the Saudi Arabian population. RESULT: Forty-one cases had positive COVID-19 infections out of a total of 58,428 pilgrims who attended the 2021 Hajj season, as detected by nonmandatory pre- and post-Hajj PCR. Notably, the 2021 Hajj season achieved a decreasing leg of the COVID-19 pandemic curve. The adjusted incidence rate in KSA from July 11th to August 7th ranged from 19 to 24 cases per 100,000 population. In contrast, the incidence rate for the same duration in Hajj ranged from 3 to 7 cases per 100,000 pilgrims. CONCLUSION: The Saudi mitigation plan ensured the safety of pilgrims and healthcare workers for Hajj, successfully limited the risk of COVID-19 transmission inside and contributed to global health security. The success story of Hajj in 2020 and 2021 during the pandemic represents a successful model for planning, achieving and managing future mass gatherings by integrating technology with global and national health policies and public health measures.

A combined model for COVID-19 pandemic control: The application of Haddon's matrix and community risk reduction tools combined.

INTRODUCTION: To mitigate morbidity, mortality, and impacts of COVID-19 on health, it was essential to implement a comprehensive framework for COVID-19 control and prevention. A well-recognized tool from the field of injury prevention known as the Haddon matrix was utilized. The matrix states that any accident is affected by the host, agent, and environment. Another well-recognized tool used by the national fire protection association known as the Community risk reduction tool (CRR). The (CRR) tool utilizes the Five E's of Community Risk Reduction. AIM OF THE STUDY: To describe the risk factors that increase the susceptibility and the severity of COVID-19 infection based on the Haddon matrix and the proposed prevention strategies by the CRR tool by using the combined model. METHODOLOGY: We reviewed the literature to assess known factors contributing to COVID-19 susceptibility, infection, and severity of infection. We then used the Haddon matrix to structure, separating human factors from technical and environmental details and timing. We then used the community risk reduction (CRR) model to set all responses and control measures for each element obtained from the Haddon matrix tool. Subsequently, we incorporated both tools to develop the combined model. CONCLUSION: we proposed and implemented a combined model that utilizes the CRR model as the systematic strategy for the more theoretical framework of Haddon's matrix. Combining both models was practical and helpful in planning the preparedness and control of the COVID-19 pandemic in Saudi Arabia that can be generalized to national and international levels.

MERS-CoV in the COVID-19 era: update from Saudi Arabia, 2019-2020.

BACKGROUND: The prevalence of Middle East respiratory syndrome coronavirus (MERS-CoV) infection during the period of coronavirus disease 2019 (COVID-19) remains uncertain. AIMS: This study aimed to provide an update on the epidemiology of MERS-CoV in Saudi Arabia from January 2019 to October 2020. METHODS: Data on all laboratory-confirmed cases of MERS-CoV infection in Saudi Arabia from January 2019 to 20 October 2020 were retrieved from the Health Electronic Surveillance Network of the Ministry of Health of Saudi Arabia. Data collected were: demographic characteristics of cases, clinical course of the infection, related mortality and association with exposure to confirmed cases or camels. RESULTS: In total, 299 cases of MERS-CoV infection were reported in the study period. The mean age of cases was 52.4 years. Most of the cases were males (78.9%) and had comorbidities (72.7%), and 11.9% of cases were health care providers. Of the 299 cases, 83 (27.7%) died. Older age and having comorbidities were associated with higher mortality. Exposure to camels was associated with lower mortality. Health care providers also had a lower mortality rate than non-health care providers. Compared with COVID-19, MERS-CoV infection still has a higher mortality rate but with a more predictable pattern and an anticipated deterioration. CONCLUSION: MERS-CoV infection remains a public health concern. The percentage of cases that were health care providers (11.9%) is lower than previously reported (19.1-25.0%), possibly due to the various preventive measures put in place to control COVID-19.

COVID-19 in Saudi Arabia: the national health response.

BACKGROUND: With the spread of coronavirus disease 2019 (COVID-19), most countries rushed to take early measures to control this disease. AIMS: This paper describes and evaluates the Saudi Arabian strategic preparedness and response plan on COVID-19 up to 31 December 2020. METHODS: Saudi Arabia adopted the World Health Organization's guidelines on response to COVID-19, which are based on nine pillars of public health preparedness and response. The measures Saudi Arabia took are assessed against these pillars. RESULTS: In response to COVID-19, Saudi Arabia prepared public and private institutions to deal with the pandemic. Saudi authorities established a governance system comprised of responsible committees to continuously monitor national and international updates, trace contacts, screen the population, raise awareness and take proper actions to contain the spread of this disease. After the announcement of the first case in Saudi Arabia, all schools, social events, sports activities, domestic travel and international flights were suspended. Restrictions on social movement, social and religious gatherings, travel and businesses were imposed ahead of the first 100 confirmed COVID-19 cases. The Hajj pilgrimage for 2020 was scaled down to limit participants and no cases of COVID-19 were detected among pilgrims. The country maintained all basic health services and immunization programmes and supported all proposals for COVID-19 drugs and vaccines. The country is working to develop its capacity to produce these products and achieve self-sufficiency. CONCLUSION: Saudi Arabia took extreme measures to respond to COVID-19 which contributed to limiting the spread and effect of the disease.

High seroprevalence of SARS-CoV-2 among high-density communities in Saudi Arabia.

BACKGROUND: The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection had been investigated utilizing serology. MATERIALS AND METHODS: This community-based sero-survey was carried out in the neighborhoods of three cities in Saudi Arabia. RESULTS: Of 5629 participants, 2766 (49.1%) were women; and 2148 (38.1%) were 18-34 years of age, and 3645 (64.7%) were from South East Asia. Positive serology was seen in 2825 (50.2% (95% CI: 48.8-51.5%) for SARS-CoV-2 anti-S1 IgG antibodies by ECLIA. Being in the age category of 18-34 years and being from Eastern Mediterranean Region (country A) were associated with higher COVID-19 seropositivity with estimated odds ratio of 1.3 [95% CI 1.1-1.8] and 2.5 [95% CI 1.1.5-4.2] respectively. Gender, social status, education, nationality, symptoms, presence of comorbidities and activity style were positively associated with increased seropositivity. Factors associated negatively with the rate of seropositivity were higher education and having outdoor activity with estimated OR of 0.92 [95% CI 0.46-0.95] and 0.59 [95% CI 0.47-0.74], respectively. CONCLUSION: The study showed high seroprevalence of SARS-CoV-2 among high density population. Health education campaigns should target middle-aged, those with low education, those living in lower standards and indoor workers.

Potential Cross-Reactive Immunity to COVID-19 Infection in Individuals With Laboratory-Confirmed MERS-CoV Infection: A National Retrospective Cohort Study From Saudi Arabia.

BACKGROUND: A growing number of experiments have suggested potential cross-reactive immunity between severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and previous human coronaviruses. We conducted the present retrospective cohort study to investigate the relationship between previous Middle East respiratory syndrome-coronavirus (MERS-CoV) infection and the risk of SARS-CoV-2 infection as well as the relationship between previous MERS-CoV and COVID-19-related hospitalization and mortality. METHODS: Starting in March 2020, we prospectively followed two groups of individuals who tested negative for COVID-19 infection. The first group had a previously confirmed MERS-CoV infection, which was compared to a control group of MERS-negative individuals. The studied cohort was then followed until November 2020 to track evidence of contracting COVID-19 infection. FINDINGS: A total of 82 (24%) MERS-positive and 260 (31%) MERS-negative individuals had COVID-19 infection. Patients in the MERS-positive group had a lower risk of COVID-19 infection than those in the MERS-negative group (Risk ratio [RR] 0.696, 95% confidence interval [CI] 0.522-0.929; p =0.014). The risk of COVID-19-related hospitalization in the MERS-positive group was significantly higher (RR 4.036, 95% CI 1.705-9.555; p =0.002). The case fatality rate (CFR) from COVID-19 was 4.9% in the MERS-positive group and 1.2% in the MERS-negative group (p =0.038). The MERS-positive group had a higher risk of death than the MERS-negative group (RR 6.222, 95% CI 1.342-28.839; p =0.019). However, the risk of mortality was similar between the two groups when death was adjusted for age (p =0.068) and age and sex (p =0.057). After controlling for all the independent variables, only healthcare worker occupation and >1 comorbidity were independent predictors of SARS-CoV-2 infection. INTERPRETATION: Individuals with previous MERS-CoV infection can exhibit a cross-reactive immune response to SARS-CoV-2 infection. Our study demonstrated that patients with MERS-CoV infection had higher risks of COVID-19-related hospitalization and death than MERS-negative individuals.

The Role of Digital Technology in Responding to COVID-19 Pandemic: Saudi Arabia's Experience.

INTRODUCTION: The novel coronavirus (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a single-chain ribonucleic acid (RNA) virus. As of March 25, 2021, the total number of positive cases and fatalities in the Kingdom of Saudi Arabia (KSA) had reached 386,300 and 6624, respectively, with a case fatality rate of 1.71%. The KSA was among the leading nations to heed the advice of WHO officials and put strict precautionary and preventive measures in place to curb the early spread of COVID-19 before it was declared a global pandemic. METHODOLOGY: This was an uncontrolled before-after study following a mixed-method approach for data collection. National and regional data were extracted from the Health Electronic Surveillance Network (HESN), a centralized public health collection system for quantitative and statistical data. Quantitative and qualitative methods have been utilized in studying data derived from tech media. RESULTS: The Saudi authorities utilized different technological tools to aid in managing and combating the COVID-19 pandemic. In the case of Al Madinah Al Mounawarah, after the implementation of several technologies, the most important being Tawakkalna, the number of active daily cases decreased by 61%. CONCLUSION: The use of the Tawakkalna application was proven to be a successful method in fighting the COVID-19 pandemic in the KSA. This vital and essential experience warrants the use of different digital technology that offers a personalized profile displaying the person's status (affected, vaccinated, or no history of infection). This application played and will continue to play a crucial and effective role in pandemic containment in Saudi Arabia.

Launching COVID-19 vaccination in Saudi Arabia: Lessons learned, and the way forward.

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARSCoV- 2) emerged in Wuhan City, China. The SARS-CoV-2 crossed borders and quickly transformed into a "Public health emergency of international concern". Countries around the globe are in the race to achieve herd immunity. We describe the steps taken by Saudi Arabia to achieve this goal.

Risk Communication Effectiveness During COVID-19 Pandemic Among General Population in Saudi Arabia.

PURPOSE: The novel coronavirus (COVID-19), declared a pandemic by WHO in March 2020, is an unprecedented occurrence in our recent history. Effective risk communication by health authorities, through relaying reliable and authoritative information, is imperative in combating the spread of the outbreak. We aimed to measure the effectiveness of risk communication campaign and overall awareness during COVID-19 pandemic among the general population in Saudi Arabia. PATIENTS AND METHODS: A cross-sectional survey of 5472 individuals in Saudi Arabia was conducted to assess several factors regarding the risk communication messages during the COVID-19 pandemic, including the knowledge and response of the general population toward COVID-19 and MoH efforts. The questionnaire was divided into five main sections: general knowledge of COVID-19, channels and social media platforms used perceived risk and stress or panic toward COVID-19, satisfaction and community perception, most trusted source of information, and type of information received. RESULTS: A total of 5472 individuals participated in the study residing in Saudi Arabia. Overall knowledge of COVID-19 was determined to be above average (0.58 + 0.159). Of the general population, 57.1% perceived that the risk of getting sick with COVID-19 is low, while nearly half of the respondents (45.7%) have a high level of stress and panic toward COVID-19. The majority of responders to the questionnaire reinforced that MoH was their most trusted source of information for the COVID-19 pandemic (91.7%). CONCLUSION: This study showed that the risk communication campaign by healthcare authorities during the COVID-19 pandemic has improved the awareness among the general population in Saudi Arabia, where the overwhelming majority placed high trust in the MoH as its main reference for COVID-19 information.

Seroprevalence of antibodies to SARS-CoV-2 among blood donors in the early months of the pandemic in Saudi Arabia.

BACKGROUND: Serologic testing provides better understanding of SARS-CoV-2 prevalence and its transmission. This study was an investigation of the prevalence of antibodies to SARS-CoV-2 among blood donors in Saudi Arabia. OBJECTIVE: To estimate the seroprevalence of anti-SARS-CoV-2 antibodies among blood donors in Saudi Arabia during the early phase of the COVID-19 pandemic. METHODS: Serology results and epidemiological data were analyzed for 837 adult blood donors, with no confirmed SARS-CoV-2 infection, in Saudi Arabia from 20th to 25th May 2020. Seroprevalence was determined using electrochemical immunoassay to detect anti-SARS-CoV-2 antibodies. RESULTS: The overall seroprevalence of anti-SARS-CoV-2 antibodies was 1.4% (12/837). Non-citizens had higher seroprevalence compared with citizens (OR 13.6, p = 0.001). Secondary education was significantly associated with higher seroprevalence compared with higher education (OR 6.8, p = 0.005). The data showed that the highest seroprevalence was in Makkah (8.1%). Uisng Makkah seroprevalence as the reference, the seroprevalence in other areas was: Madinah 4.1% (OR 0.48, 95% CI 0.12-1.94), Jeddah 2.3% (OR 0.27, 95% CI 0.31-2.25), and Qassim 2.9 % (OR 0.34, 95% CI 0.04-2.89) and these were not statistically different from seroprevalence in the Makkah region. CONCLUSIONS: At the early months of the COVID-19 pandemic in Saudi Arabia, the seroprevalence of antibodies to SARS-CoV-2 among blood donors was low, but was higher among non-citizens. These findings may indicate that non-citizens and less educated individuals may be less attentive to preventive measures. Monitoring seroprevalence trends over time require repeated sampling.

Seroprevalence of SARS-CoV-2 (COVID-19) among healthcare workers in Saudi Arabia: comparing case and control hospitals.

Healthcare workers (HCWs) stand at the frontline for fighting coronavirus disease 2019 (COVID-19) pandemic. This puts them at higher risk of acquiring the infection than other individuals in the community. Defining immunity status among health care workers is therefore of interest since it helps to mitigate the exposure risk. This study was conducted between May 20th and 30th, 2020. Eighty-five hospitals across Kingdom of Saudi Arabia were divided into 2 groups: COVID-19 referral hospitals are those to which RT-PCR-confirmed COVID-19 patients were admitted or referred for management (Case-hospitals). COVID-19 nonaffected hospitals where no COVID-19 patients had been admitted or managed and no HCW outbreak (Control hospitals). Next, seroprevalence of severe acute respiratory syndrome coronavirus 2 among HCWs was evaluated; there were 12,621 HCWs from the 85 hospitals. There were 61 case-hospitals with 9379 (74.3%) observations, and 24 control-hospitals with 3242 (25.7%) observations. The overall positivity rate by the immunoassay was 299 (2.36%) with a significant difference between the case-hospital (2.9%) and the control-group (0.8%) (P value <0.001). There was a wide variation in the positivity rate between regions and/or cities in Saudi Arabia, ranging from 0% to 6.31%. Of the serology positive samples, 100 samples were further tested using the SAS2pp neutralization assay; 92 (92%) samples showed neutralization activity. The seropositivity rate in Kingdom of Saudi Arabia is low and varies across different regions with higher positivity in case-hospitals than control-hospitals. The lack of neutralizing antibodies (NAb) in 8% of the tested samples could mean that assay is a more sensitive assay or that neutralization assay has a lower detection limits; or possibly that some samples had cross-reaction to spike protein of other coronaviruses in the assay, but these were not specific to neutralize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).