Herd Immunity against Severe Acute Respiratory Syndrome Coronavirus 2 Infection in 10 Communities, Qatar.

We investigated what proportion of the population acquired severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and whether the herd immunity threshold has been reached in 10 communities in Qatar. The study included 4,970 participants during June 21-September 9, 2020. Antibodies against SARS-CoV-2 were detected by using an electrochemiluminescence immunoassay. Seropositivity ranged from 54.9% (95% CI 50.2%-59.4%) to 83.8% (95% CI 79.1%-87.7%) across communities and showed a pooled mean of 66.1% (95% CI 61.5%-70.6%). A range of other epidemiologic measures indicated that active infection is rare, with limited if any sustainable infection transmission for clusters to occur. Only 5 infections were ever severe and 1 was critical in these young communities; infection severity rate of 0.2% (95% CI 0.1%-0.4%). Specific communities in Qatar have or nearly reached herd immunity for SARS-CoV-2 infection: 65%-70% of the population has been infected.

SARS-CoV-2 PCR and antibody positivity among school staff at the beginning and end of the first school term.

BACKGROUND: There is controversy regarding the role of in-person attendance in schools and transmission of the SARS-CoV-2 pandemic. Several studies have demonstrated no increase in transmission, while some have reported large outbreaks with in-person attendance. We determined the incidence and risk factors for SARS-CoV-2 infection among school staff after one school term. METHODS: Nasopharyngeal swabs (NPS) for SARS-CoV-2 RT-PCR and blood for SARS-CoV-2 antibody testing were obtained from staff at a large international school in Qatar at the beginning of the 2020-2021 school year and repeated at the end of the first term. RESULTS: A total of 376 staff provided samples for testing. At the beginning of the 2020-2021 school year, the PCR positivity for SARS-CoV-2 was 13%, while seropositivity was 30.1%. A majority of those who tested positive either by PCR or serologically, were non-teaching staff. At the end of the first school term four months later, only 3.5% of the initially antibody-negative staff had seroconverted. In multivariable logistic regression analysis, male gender (OR 11.48, 95%CI 4.77-27.64), non-teaching job category (OR 3.09, 95%CI 1.10-8.64), contact with a confirmed case (OR 20.81, 95%CI 2.90-149.18), and presence of symptoms in the preceding 2 weeks [1-2 symptoms OR 4.82, 95%CI 1.79-12.94); ≥3 symptoms OR 42.30, 95%CI 3.76-476.43) independently predicted SARS-CoV-2 infection in school staff before school starting. CONCLUSION: Male gender, non-teaching job, presence of symptoms, and exposure to a confirmed case were associated with higher risk of infection. These data can help policymakers in determining the optimal strategy for school reopening.

SARS-CoV-2 infection prevalence, risk factors, and outcomes among non-clinical-related service providers in a national healthcare system.

Health care workers (HCWs) may be at a variable risk of SARS-CoV2 infection. Regardless of their involvement in providing direct clinical treatment, most of the prior research had included all HCWs. Understanding infection rates, risk factors and outcomes among different subgroups of HCWs is crucial. From February 28, 2020 to January 1, 2022, we conducted a retrospective analysis encompassing all full-time non-clinical staff (NCS) subcontracted with Hamad Medical Corporation (HMC) facilities. To determine current or previous SARS-CoV2 infection, all personnel underwent RT-PCR and/or serology testing. To identify the demographic factors linked to the risk of infection, we utilized Cox-Hazard regression analysis. Herein 3158/6231 (50.7%) subcontracted NCS tested positive for SARS-CoV-2 by RT-PCR or serology during the research period. The median age was 30 years (IQR 25,35), 69.8% of the population were males, 82.4% were from South Asia, 86.6% did not have any concomitant conditions. 6032 (96.8%) of the population lived in shared housing, while 4749 (76.2%) had low to median levels of education. While infection (PCR positive with or without seropositive results) was independently predicted by male gender, working in the catering, laundry, and security sectors and being intermediate (7-12 years of education), lower (0-6 years of education), higher (exposure to confirmed case), and having symptoms. Male gender, working in the security sectors and being intermediate (7-12 years of education) were independently associated with accidently detected cases (PCR negative and seropositive). 299 (4.8%) required hospitalization, of them 3 cases were severe pneumonia and one required ICU admission without mechanical ventilation, with no deaths reported. In conclusion Infection rates among NCS are high. The majority are asymptomatic and may contribute to ongoing illness spread in the public or in healthcare facilities. During a pandemic, routine screening of this population is crucial and may aid in containing the spread of infection.

SARS-CoV-2 infection in 3,241 School working staffs: Impact of SARS CoV-2 variants of concern [Wild, B.1.1.7 and Omicron].

BACKGROUND: There is debate over whether physical attendance at school affects the spread of the SARS-CoV-2 pandemic. METHODS: A cohort of personnel from several schools in Qatar provided nasopharyngeal swabs (NPS) for SARS-CoV-2 RT-PCR and rapid antigen testing. Each of them was monitored for infection until February 2022. RESULTS: In total, 3,241 employees gave samples for analysis. Prior to the start of the 2020-2021 academic year (Group I), 3.49% of samples tested positive for SARS-CoV-2. Most of the positive PCR results were from male, senior, non-teaching staff members. Only 110 (3.39%) employees who had enrolled in face-to-face instruction before the B.1.1.7 variant's emergence (Group II), 238 (7.34%) after the B.1.1.7 variant's emergence (Group III), and 410 (12.65%) after the introduction of the Omicron variant (Group IV) had reported infection by PCR test. Most people who tested positive by PCR after enrolling in school were young, female teachers. In the Cox Proportional-Hazards Model, exposure to a confirmed case, the presence of symptoms in the two weeks prior to exposure in all groups-young age in Groups II and III, male gender in Groups I and IV, shared housing in Group III, and the presence of comorbidities in Groups II and III independently predicted SARS-CoV-2 infection in school staff. CONCLUSION: Critical information about the risk of SARS-CoV-2 infection in school workers during the whole pandemic is provided by our study. School operations in Qatar were made safer through initial and ongoing screenings, as well as widespread vaccination of school personnel.

Seroprevalence of SARS-CoV-2 Infection Among Working Women and Impact of Workplace Restrictions.

Objective: To determine the prevalence of SARS-CoV-2 virus infection among female workers who were restricted to working from home compared with those who continued to attend in-person work. Methods: As part of national surveillance program, serum samples for SARS-CoV-2 antibody testing and nasopharyngeal swabs for SARS-CoV-2 PCR were obtained on 1636 female school staff and salon/spa workers who were restricted to work remotely (restricted group) and 1190 female health-care workers who continued in-person work (unrestricted group). Results: Seropositivity rate was 5.1% among the restricted and 22.7% among the unrestricted group (P < 0.0001). Presence of symptoms at baseline (adjusted odds ratio [aOR], 2.88; 95% CI 2.09-3.97), contact with a confirmed case (aOR 2.34; 95% CI 1.37-3.98), and unrestricted work type (aOR 4.71; 95% CI 3.24-6.86) were associated with a higher risk of infection, while increasing age was associated with a lower risk of infection. Conclusion: Prevalence of SARS-CoV-2 infection as determined by seropositivity was higher among women who were not subject to workplace restrictions.

Investigation of a COVID-19 Outbreak and Its Successful Containment in a Long Term Care Facility in Qatar.

Introduction: The objective of this study is to investigate the COVID-19 outbreak and its successful containment in a long-term care facility, Qatar. Materials and Methods: It was a retrospective case series of 24 COVID-19 positive patients inclusive of elderly, patient attenders, and front-liners from 06th to 18th June 2020. Laboratory, radiological, and treatment findings were assessed from electronic records. Results: The outbreak management team concluded that despite all the pre-existing preventive measures implemented at the start of the pandemic, there was still evidence of lapses in infection control practices such as breach of infection control protocols like improper use of personal protective equipment. The infection prevention and control team promptly reassessed and implemented more stringent infection control methods and practices that successfully contained the outbreak on July 1, 2020. Among the seven elderly patients, the average age was 76.28 years ± SD25.5 and all were females. 57% of the patients were symptomatic. The most common comorbidities were Dementia (57%), Diabetes mellitus (43%), Coronary Artery Disease (43%), and Seizures (43%). Ground glass appearances in the lungs were found in 29% of the patients. Among the three deceased patients, Dementia and Coronary Artery Disease were the common comorbidities. Persistent elevation in blood glucose levels was observed among all patients during this period of infection. Conclusion: Elderlies in long-term care facilities are with certain pre-existing comorbidities which makes them more prone to develop COVID-19 complications. Thus, intensive infection control measures like ongoing education and awareness, staff compliance monitoring, quick contact tracing, visitor policy revision, ongoing patient and caregivers monitoring are inevitable recommendations for effective outbreak prevention and management.

Risk factors for breakthrough SARS-CoV-2 infection in vaccinated healthcare workers.

BACKGROUND AND OBJECTIVE: The risk factors for breakthrough infections among healthcare workers (HCW) after completion of a full course of vaccination are poorly understood. Our objective was to determine the risk factors for breakthrough SARS-CoV-2 infection among HCWs at a national healthcare system in Qatar. METHODS: We identified all HCWs at Hamad Medical Corporation in Qatar between December 20, 2020 and May 18, 2021 with confirmed SARS-CoV-2 RT-PCR infection >14 days after the second vaccine dose. For each case thus identified, we identified one control with a negative test after December 20, 2020, matched on age, sex, nationality, job family and date of SARS-CoV-2 testing. We excluded those with a prior positive test and temporary workers. We used Cox regression analysis to determine factors associated with breakthrough infection. RESULTS: Among 22,247 fully vaccinated HCW, we identified 164 HCW who had breakthrough infection and matched them to 164 controls to determine the factors associated with SARS-CoV-2 breakthrough infection. In the breakthrough infection group the nursing and midwifery job family constituted the largest group, spouse was identified as the most common positive contact followed by a patient. Exposure to a confirmed case, presence of symptoms and all other job families except Allied Health Professionals when compared with nursing and Midwifery staff independently predicted infection. CONCLUSION: Presence of symptoms and contact with a confirmed case are major risk factors for breakthrough SARS-CoV-2 infection after vaccination, and these groups should be prioritized for screening even after full vaccination.

SARS-CoV-2 infection in mortuary and cemetery workers.

BACKGROUND: Mortuary and cemetery workers may be exposed to the bodies of people with SARS-CoV-2 infection; however, prevalence of infection among these groups is unknown. METHODS: Nasopharyngeal swabs (NPS) for RT-PCR and serologic testing for SARS-CoV-2 were performed on mortuary and cemetery workers in Qatar. Data on specific job duties, living conditions, contact history, and clinical course were gathered. Environmental sampling was carried out to explore any association with infection. Logistic regression analysis was used to determine the factors associated with infection. RESULTS: Forty-seven mortuary workers provided an NPS and seven (14.9%) were PCR positive; 32 provided a blood sample and eight (25%) were antibody positive, six (75%) who were seropositive were also PCR positive. Among the 81 cemetery workers, 76 provided an NPS and five (6.6%) were PCR positive; 64 provided a blood sample and 22 (34.4%) were antibody positive, three (13.6%) who were seropositive were also PCR positive. Three (22.2%) and 20 (83.3%) of the infected mortuary and cemetery workers were asymptomatic, respectively. Age <30 years (OR 4.9, 95% CI 1.7-14.6), community exposure with a known case (OR 4.7, 95% CI 1.7-13.3), and presence of symptoms in the preceding 2 weeks (OR 9.0, 95% CI 1.9-42.0) were independently associated with an increased risk of infection (PCR or antibody positive). Of the 46 environmental and surface samples, all were negative or had a Ct value of >35. CONCLUSION: A substantial proportion of mortuary and cemetery workers had evidence of SARS-CoV-2 infection, which was incidentally detected upon serologic testing. These data are most consistent with community acquisition rather than occupational acquisition.