Immediate and contributory causes of death in patients hospitalized with COVID-19.

OBJECTIVES: Accurate determination of the immediate causes of death in patients with COVID-19 is important for optimal care and mitigation strategies. METHODS: All deaths in Qatar between March 01, 2020, and August 31, 2022, flagged for likely relationship to COVID-19 were reviewed by two independent, trained reviewers using a standardized methodology to determine the immediate and contributory causes of death. RESULTS: Among 749 flagged deaths, the most common admitting diagnoses were respiratory tract infection (91%) and major adverse cardiac event (MACE, 2.3%). The most common immediate causes of death were COVID-19 pneumonia (66.2%), MACE (7.1%), hospital-associated pneumonia (HAP, 6.8%), bacteremia (6.3%), disseminated fungal infection (DFI, 5.2%), and thromboembolism (4.5%). After COVID-19 pneumonia, MACE was the predominant cause of death in the first 2 weeks but declined thereafter. No death occurred due to bacteremia, HAP, or DFI in the first week after hospitalization, but became increasingly common with increased length of stay in the hospital accounting for 9%, 12%, and 10% of all deaths after 4 weeks in the hospital, respectively. CONCLUSION: Nearly one-third of patients with COVID-19 infection die of non-COVID-19 causes, some of which are preventable. Mitigation strategies should be instituted to reduce the risk of such deaths.

Effectiveness of Messenger RNA Vaccines against SARS-CoV-2 Infection in Hemodialysis Patients: A Case-Control Study.

Patients with end-stage kidney disease (ESKD) are at increased risk for SARS-CoV-2 infection and its complications compared with the general population. Several studies evaluated the effectiveness of COVID-19 vaccines in the dialysis population but showed mixed results. The aim of this study was to determine the effectiveness of COVID-19 mRNA vaccines against confirmed SARS-CoV-2 infection in hemodialysis (HD) patients in the State of Qatar. We included all adult ESKD patients on chronic HD who had at least one SARS-CoV-2 PCR test done after the introduction of the COVID-19 mRNA vaccines on 24 December 2020. Vaccinated patients who were only tested before receiving any dose of their COVID-19 vaccine or within 14 days after receiving the first vaccine dose were excluded from the study. We used a test-negative case−control design to determine the effectiveness of the COVID-19 vaccination. Sixty-eight patients had positive SARS-CoV-2 PCR tests (cases), while 714 patients had negative tests (controls). Ninety-one percent of patients received the COVID-19 mRNA vaccine. Compared with the controls, the cases were more likely to be older (62 ± 14 vs. 57 ± 15, p = 0.02), on dialysis for more than one year (84% vs. 72%, p = 0.03), unvaccinated (46% vs. 5%, p < 0.0001), and symptomatic (54% vs. 21%, p < 0.0001). The effectiveness of receiving two doses of COVID-19 mRNA vaccines against confirmed SARS-CoV-2 infection was 94.7% (95% CI: 89.9−97.2) in our HD population. The findings of this study support the importance of using the COVID-19 mRNA vaccine in chronic HD patients to prevent SARS-CoV-2 infection in such a high-risk population.

Evaluation of mortality attributable to SARS-CoV-2 vaccine administration using national level data from Qatar.

Accurate determination of mortality attributable to SARS-CoV-2 vaccination is critical in allaying concerns about their safety. We reviewed every death in Qatar that occurred within 30 days of any SARS-CoV-2 vaccine administration between January 1, 2021 and June 12, 2022. Probability of association with SARS-CoV-2 vaccination was determined by four independent trained reviewers using a modified WHO algorithm. Among 6,928,359 doses administered, 138 deaths occurred within 30 days of vaccination; eight had a high probability (1.15/1,000,000 doses), 15 had intermediate probability (2.38/1,000,000 doses), and 112 had low probability or no association with vaccination. The death rate among those with high probability of relationship to SARS-CoV-2 vaccination was 0.34/100,000 unique vaccine recipients, while death rate among those with either high or intermediate probability of relationship to SARS-CoV-2 vaccination was 0.98/100,000 unique vaccine recipients. In conclusion, deaths attributable to SARS-CoV-2 vaccination are extremely rare and lower than the overall crude mortality rate in Qatar.

COVID-19 Disease Severity in Persons Infected With Omicron BA.1 and BA.2 Sublineages and Association With Vaccination Status.

This retrospective study compares the severity of SARS-CoV-2 infection among persons infected with BA.1 and BA.2 sublineages by vaccination status.

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.

COVID-19 disease severity in persons infected with the Omicron variant compared with the Delta variant in Qatar.

Background: Understanding the disease severity associated with the Omicron variant of the SARS-CoV-2 virus is important in determining appropriate management strategies at the individual and population levels. We determined the severity of SARS-CoV-2 infection in persons infected with the Omicron vs the Delta variant. Methods: We identified individuals with SARS-CoV-2 infection with Delta and propensity-score matched controls with Omicron variant infection from the National COVID-19 Database in Qatar. We excluded temporary visitors to Qatar, those with a prior documented infection, those ≤18 years old, and those with <14 days of follow up after the index test positive date. We determined the rates of admission to the hospital, admission to intensive care unit, mechanical ventilation, or death among those infected with the Delta or Omicron variants. Results: Among 9763 cases infected with the Delta variant and 11 310 cases infected with the Omicron variant, we identified 3926 propensity-score matched pairs. Among 3926 Delta infected, 3259 (83.0%) had mild, 633 (16.1%) had moderate and 34 (0.9%) had severe/critical disease. Among 3926 Omicron infected, 3866 (98.5%) had mild, 59 (1.5%) had moderate, and only 1 had severe/critical disease (overall P < 0.001). Factors associated with less moderate or severe/critical disease included infection with Omicron variant (aOR = 0.06; confidence interval (CI) = 0.05-0.09) and vaccination including a booster (aOR = 0.30; 95% CI = 0.09-0.99). Conclusions: Omicron variant infection is associated with significantly lower severity of disease compared with the Delta variant. Vaccination continues to offer strong protection against severe/critical disease.

Coronavirus Disease 2019 Disease Severity in Children Infected With the Omicron Variant.

SHORT SUMMARY: Severe acute respiratory syndrome coronavirus 2 infection from the Omicron variant in children/adolescents is less severe than infection from the Delta variant. Those 6 to <18 years also have less severe disease than those <6 years old. BACKGROUND: There are limited data assessing coronavirus 2019 (COVID-19) disease severity in children/adolescents infected with the Omicron variant. METHODS: We identified children and adolescents <18 years of age with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with Delta and propensity score-matched controls with Omicron variant infection from the National COVID-19 Database in Qatar. Primary outcome was disease severity, determined by hospital admission, admission to the intensive care unit (ICU), or mechanical ventilation within 14 days of diagnosis, or death within 28 days. RESULTS: Among 1735 cases with Delta variant infection between 1 June and 6 November 2021, and 32 635 cases with Omicron variant infection between 1 January and 15 January 2022, who did not have prior infection and were not vaccinated, we identified 985 propensity score-matched pairs. Among those who were Delta infected, 84.2% had mild, 15.7% had moderate, and 0.1% had severe/critical disease. Among those who were Omicron infected, 97.8% had mild, 2.2% had moderate, and none had severe/critical disease (P < .001). Omicron variant infection (vs Delta) was associated with significantly lower odds of moderate or severe/critical disease (adjusted odds ratio [AOR], 0.12; 95% confidence interval [CI], .07-.18). Those aged 6-11 and 12 to <18 years had lower odds of developing moderate or severe/critical disease compared with those younger than age 6 years (aOR, 0.47; 95% CI, .33-.66 for 6-11 year olds; aOR, 0.45; 95% CI, .21-.94 for 12 to <18 year olds). CONCLUSIONS: Omicron variant infection in children/adolescents is associated with less severe disease than Delta variant infection as measured by hospitalization rates and need for ICU care or mechanical ventilation. Those 6 to <18 years of age also have less severe disease than those <6 years old.

Severity of Illness in Persons Infected With the SARS-CoV-2 Delta Variant vs Beta Variant in Qatar.

Importance: The Delta variant is now the predominant circulating SARS-CoV-2 strain worldwide. Severity of illness in persons infected with the SARS-CoV-2 Delta variant compared with the Beta variant is not known. Objective: To directly compare clinical outcomes in persons infected with the SARS-CoV-2 Delta variant vs those infected with the Beta variant in Qatar. Design, Setting, and Participants: This retrospective cohort study used data from the national COVID-19 database in Qatar, which includes information on all individuals who were ever tested for SARS-CoV-2 using a reverse transcriptase-polymerase chain reaction test and all individuals who received any SARS-CoV-2 vaccine in Qatar. Among persons with confirmed SARS-CoV-2 infection between March 22 and July 7, 2021, those infected with the Delta variant were identified and were propensity score matched with control individuals infected with the Beta variant. The variants were ascertained by variant genotyping of the positive samples. Exposures: SARS-CoV-2 infection with the Delta or Beta variant. Main Outcomes and Measures: The main outcomes were admission to the hospital, admission to the intensive care unit, use of supplemental oxygen, use of high-flow oxygen, receipt of mechanical ventilation, or death among those infected with the Delta or Beta variant overall and stratified by vaccination status. Results: Among 1427 persons infected with the Delta variant (252 [55.9%] male; median age, 34 years [IQR, 17-43 years]) and 5353 persons infected with the Beta variant (233 [51.7%] male; median age, 34 years [IQR, 17-45 years]), 451 propensity score-matched pairs were identified. Persons infected with the Delta variant were more likely to be hospitalized (27.3% [95% CI, 23.2%-31.6%] vs 20.0% [95% CI, 16.4-24.0]; P = .01) or to have mild-moderate or severe-critical disease outcomes (27.9% [95% CI, 23.8%-32.3%] vs 20.2% [95% CI, 16.6%-24.2%]; P = .01) compared with persons infected with the Beta variant. Infection with the Delta variant was independently associated with higher odds of experiencing any adverse outcome (adjusted odds ratio [aOR], 2.53; 95% CI, 1.72-3.72). Compared with being unvaccinated, being vaccinated with a second dose more than 3 months before infection was associated with lower odds of any adverse outcome among persons infected with the Delta variant (aOR, 0.11; 95% CI, 0.04-0.26) and among those infected with the Beta variant (aOR, 0.22; 95% CI, 0.05-0.98). Protection was similar among those who received a second vaccine dose less than 3 months before infection, but having received only a single dose was not associated with a lower odds of any severe outcome among those infected with the Delta variant (aOR, 1.12; 95% CI, 0.41-3.06) or those infected with the Beta variant (aOR, 0.74; 95% CI, 0.20-2.72). Conclusions and Relevance: In this cohort study of persons with COVID-19 in Qatar, infection with the SARS-CoV-2 Delta variant was associated with more severe disease than was infection with the Beta variant. Being unvaccinated was associated with greater odds of severe-critical disease.

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 vaccine effectiveness in preventing confirmed infection in pregnant women.

BackgroundSARS-CoV-2 infection in pregnancy is associated with a higher risk of pregnancy-related complications and neonatal respiratory distress and hospitalization. Effectiveness of SARS-CoV-2 vaccines in pregnant women is not known.MethodsAll women with confirmed pregnancy who presented to the national referral hospital in Qatar between December 20, 2020, and May 30, 2021, with at least 1 SARS-CoV-2 test and not testing prior to pregnancy were included. We determined the vaccine effectiveness of mRNA vaccines in preventing confirmed SARS-CoV-2 infection during pregnancy using both cohort and test-negative case-control designs. Analyses were adjusted for age group, nationality, and gestational age.ResultsAmong 4534 pregnant women, there were 407 vaccinated and 407 unvaccinated women in the matched cohort analysis. Vaccine effectiveness was 87.6% (95%CI 44.1%-97.2%) at least 14 days after the second dose. There were 386 test-positive and 834 matched women in the test-negative case control analysis. Vaccine effectiveness was 86.8% (95%CI 47.5%-98.5%) at least 14 days after the second dose. Adjustment for age, nationality, and gestational age yielded similar results for both designs. In the test-negative analysis, vaccine effectiveness at least 14 days after the first dose but before the second dose was 40.8% (95% CI 0.0%-80.4%). Of the 386 test-positive pregnant women, 74 cases were Alpha variant, 163 cases were Beta variant, and 156 cases were variants of unknown status. There were 9 severe or critical disease cases and no deaths in the test-positive pregnant women, all of whom were unvaccinated.ConclusionThe mRNA vaccines provide a high level of protection against documented SARS-CoV-2 infection, which supports the inclusion of pregnant women in vaccination campaigns.FUNDINGHamad Medical Corporation, Weill Cornell Medicine Qatar, and the Ministry of Public Health Qatar.

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.

Prevalence and risk factors for SARS-CoV-2 infection and seroprevalence among clinical and non-clinical staff in a national healthcare system.

BACKGROUND: While many studies have reported the rate and risk of SARS-CoV-2 infection among healthcare workers (HCWs), there are scant data regarding the impact of employment type and job grades upon such risk. METHODS: We determined the rate of SARS-CoV-2 infection based on a positive nasopharyngeal swab (NPS) PCR among employees of a large national healthcare system. Antibody testing was performed on those who agreed to provide a blood sample. Using logistic regression analysis, we determined the risk of infection (PCR+) associated with demographic characteristics, job family and job grade. RESULTS: We identified 35,075 staff (30,849 full-time, 4,226 outsourced) between March 1-October 31, 2020. Among full-time employees, 78.0% had a NPS (11.8% positive). Among outsourced staff, 94.4% had a NPS (31.1% positive). Antibody testing was performed on 33.9% full-time employees (13.0% reactive), and on 39.1% of the outsourced staff (47.0% reactive). PCR-positivity was higher among outsourced staff (31.0% vs. 18.3% in non-clinical and 9.0% in clinical full-time employees) and those in the low-grade vs. mid-grade and high-grade job categories. Male sex (OR 1.88), non-clinical job family (OR 1.21), low-grade job category (OR 3.71) and being an outsourced staff (OR 2.09) were associated with a higher risk of infection. CONCLUSION: HCWs are a diverse population with varying risk of infection. Clinical staff are at a lower risk likely due to increased awareness and infection prevention measures. Risk is higher for those in the lower socioeconomic strata. Infection is more likely to occur in non-healthcare setting than within the healthcare facilities.

Outcomes Among Patients with Breakthrough SARS-CoV-2 Infection After Vaccination.

BACKGROUND: Breakthrough infections after SARS-CoV-2 vaccination have been reported. Clinical outcomes in these persons are not widely known. METHODS: We evaluated all vaccinated persons with breakthrough infection ≥14 days after the second vaccine dose and unvaccinated controls matched on age, sex, nationality, and reason for testing between December 23, 2020 and March 28, 2021 in Qatar. Our primary outcome was severe disease defined as hospitalization, mechanical ventilation, or death. RESULTS: Among 456 persons cases of breakthrough infection and 456 unvaccinated matched controls with confirmed infection, median age was 45 years, 60.7% were males, and ≥1 comorbid condition was present in 61.2% of the vaccinated and 47.8% of the unvaccinated persons (P=0.009). Severe disease was recorded in 48 (10.5%) of the vaccinated and 121 (26.5%) of the unvaccinated group (P<0.001). Factors associated with severe disease included increasing age (HR vs. <40 years old: >40-60 years, HR 2.32; >60-70 years, HR 4.34; >70 years, HR 5.43); presence of symptoms at baseline (HR 2.42, 95%CI 1.44-4.07); and being unvaccinated (HR 2.84, 95%CI 1.80-4.47). CONCLUSIONS: In persons with breakthrough SARS-CoV-2 infection, increasing age is associated with a higher risk of severe disease or death, while vaccination is associated with a lower risk. Presence of comorbidities was not associated with severe disease or death among persons with breakthrough infection.

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 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.

Impact of COVID-19 upon changes in emergency room visits with chest pain of possible cardiac origin.

OBJECTIVES: A decrease in Emergency Department (ED) visits for cardiac conditions has recently been reported from the US and Western Europe due to the COVID-19 pandemic. The data are still scant, and the correlation between cardiac symptoms and confirmed diagnoses are not available. There are no reports on changes in ED volumes at a national level, or from countries in the Asia-Middle Eastern region. We report data from national referral centers for tertiary care and cardiac care centers in Qatar, which see > 80% of cardiac emergencies in the country. RESULTS: We analyzed 102,033 ED visits in the COVID-19-era (March-April 2020 and 2019) and determined the proportion presenting for cardiac symptoms and their confirmed diagnoses. We observed a 16-37% decline in ED volumes overall, with a 25-50% decline in patients presenting with cardiac symptoms in March and April 2020 compared with March and April 2019. Among those presenting with cardiac symptoms, we observed a 24-43% decline in cardiac diagnoses in March and April 2020 compared with March and April 2019.

Epidemiological investigation of the first 5685 cases of SARS-CoV-2 infection in Qatar, 28 February-18 April 2020.

OBJECTIVE: To define the epidemiological curve of COVID-19 in Qatar and determine factors associated with severe or critical illness. DESIGN: Case series of first 5685 COVID-19 cases in Qatar. SETTING AND PARTICIPANTS: All confirmed COVID-19 cases in the State of Qatar between 28 February and 18 April 2020. MAIN OUTCOME MEASURES: Number of total and daily new COVID-19 infections; demographic characteristics and comorbidity burden and severity of infection; factors associated with severe or critical illness. RESULTS: Between 28 February and 18 April 2020, 5685 cases of COVID-19 were identified. Median age was 34 (IQR 28-43) years, 88.9% were male and 8.7% were Qatari nationals. Overall, 83.6% had no concomitant comorbidity, and 3.0% had three or more comorbidities. The overwhelming majority (90.9%) were asymptomatic or with minimal symptoms, with 2.0% having severe or critical illness. Seven deaths were observed during the time interval studied. Presence of hypertension or diabetes was associated with a higher risk of severe or critical illness, but age was not. The epidemiological curve indicated two distinct patterns of infection, a larger cluster among expatriate craft and manual workers and a smaller one among Qatari nationals returning from abroad during the epidemic. CONCLUSION: COVID-19 infections in Qatar started in two distinct clusters, but then became more widespread in the population through community transmission. Infections were mostly asymptomatic or with minimal symptoms and associated with very low mortality. Severe/critical illness was associated with presence of hypertension or diabetes but not with increasing age.

COVID-19 infection among healthcare workers in a national healthcare system: The Qatar experience.

BACKGROUND: Our aim was to determine the prevalence of COVID-19 infection in healthcare workers (HCWs) in a national healthcare system and to understand the risk factors for infection. METHODS: The study was conducted at Hamad Medical Corporation (HMC) in Qatar, a national healthcare system with 14 hospitals and >28,000 employees, between March 10 and June 24, 2020. Data on COVID-19+ HCWs were retrieved from the electronic health records and employment records, followed by an email survey and a focused telephone interview. RESULTS: Among 16,912 HCWs tested, 10.6% tested positive. Hospitalization rate was 11.6%, 1.3% required supplemental oxygen, 0.6% needed intensive care unit admission, and 0.3% required mechanical ventilation. There were no deaths. In a follow-up survey of 393 HCWs, 5% reported acquiring infection at a COVID-19-designated facility and 95% at a non-COVID-19 facility having acquired the infection through accidental exposure to a colleague (45%) or a patient (29%). Full personal protective equipment (PPE) adherence was 82% at COVID-19-designated facilities but only 68% at non-COVID-19 facilities. CONCLUSIONS: COVID- 19 infection among HCWs often occurs among those not directly working with COVID-19 patients. PPE use is less stringent in such settings. Risk of exposure and need for strict PPE must be stressed upon all HCWs in all settings.