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.
METHODOLOGY: Patients' socio-demographic and epidemiological data, clinical features, laboratory findings and clinical outcomes were extracted using a data sheet.
RESULTS: The median patient age was 25 [interquartile range (IQR)] 20-44) years, and most of patients were male (68.7%) and of Malaysian nationality (88.4%). Almost half of the patients were from a case cluster related to a religious event (48.3%) and 12.9% had a history of overseas travel. A total of 33.3% of patients were not related to any case cluster, i.e. sporadic cases. Radiological investigation showed that 13.6% of the patients had chest X-ray changes and all laboratory parameters were within the normal ranges. Sixty-six patients (44.9%) experienced symptoms. The most common symptoms were rhinitis (66.7%), followed by fever (19.7%) and cough (15.2%). Age, gender, case cluster, comorbidity status, haemoglobin, albumin, total protein, bilirubin total and alkaline phosphatase level were associated with symptomatic status.
CONCLUSIONS: In this single-centre study, COVID-19 infection led not only to case clusters, but also to sporadic infections, with patients being either symptomatic or asymptomatic. These sporadic cases and asymptomatic patients may hamper effective contact tracing, leading to rapid human-to-human transmission in our population. Future studies on the prevalence and clinical significance of asymptomatic and presymptomatic COVID-19 patients would pre-emptively address issues on further containment of the pandemic.