First nosocomial cluster of COVID-19 due to the Delta variant in a major acute care hospital in Singapore: investigations and outbreak response.

OBJECTIVES: The first large nosocomial cluster of coronavirus disease 2019 (COVID-19) in Singapore in April 2021 led to partial closure of a major acute care hospital. This study examined factors associated with infection among patients, staff and visitors; investigated the possible role of aerosol-based transmission; evaluated the effectiveness of BNT162.b2 and mRNA1273 vaccines; and described the successful containment of the cluster. METHODS: Close contacts of patients with COVID-19 and the affected ward were identified and underwent surveillance for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Patient, staff and visitor cohorts were constructed and factors associated with infection were evaluated. Phylogenetic analysis of patient samples was performed. Ward air exhaust filters were tested for SARS-CoV-2. RESULTS: In total, there were 47 cases, comprising 29 patients, nine staff, six visitors and three household contacts. All infections were of the Delta variant. Ventilation studies showed turbulent air flow and swabs from air exhaust filters were positive for SARS-CoV-2. Vaccine breakthrough infections were seen in both patients and staff. Among patients, vaccination was associated with a 79% lower odds of infection with COVID-19 (adjusted odds ratio 0.21, 95% confidence interval 0.05-0.95). CONCLUSIONS: This cluster occurred despite enhancement of infection control measures that the hospital had undertaken at the onset of the COVID-19 pandemic. It was brought under control rapidly through case isolation, extensive contact tracing and quarantine measures, and led to enhanced use of hospital personal protective equipment, introduction of routine rostered testing of inpatients and staff, and changes in hospital infrastructure to improve ventilation within general wards.

Coronavirus Disease 2019 (COVID-19): The Singapore Experience. A Review of the First Eight Months

As of 27 October 2020, there have been 57,980 confirmed cases of COVID-19 in Singapore, with 28 fatalities. To summarise the Singapore experience in managing and containing COVID-19 based on available published data and from relevant sources, a review of literature using research databases such as PubMed and OVID Medline, along with non-peer-reviewed articles and other sources, was conducted with the search terms 'COVID-19' and 'Singapore'. Research conducted in Singapore has provided insight into the clinical manifestations and period of infectivity of COVID-19, demonstrated evidence of pre-symptomatic transmission, linked infection clusters using serological tools, and highlighted aspects of hospital-based environmental contamination. It has also provided guidance for diagnostic testing and has described immune and virologic correlates with disease severity. Evidence of effectiveness of containment measures such as early border control, rigorous contact training, and calibrated social distancing measures have also been demonstrated. Singapore's multipronged strategy has been largely successful at containing COVID-19 and minimising fatalities, but the risk of re-emergence is high.

Neuroimaging in Zoonotic Outbreaks Affecting the Central Nervous System: Are We Fighting the Last War?

When preparing for the coronavirus disease 2019 pandemic and its effects on the CNS, radiologists should be familiar with neuroimaging appearances in past zoonotic infectious disease outbreaks. Organisms that have crossed the species barrier from animals to humans include viruses such as Hendra, Nipah, Severe Acute Respiratory Syndrome, and influenza, as well as bacteria and others. Brain CT and MR imaging findings have included cortical abnormalities, microinfarction in the white matter, large-vessel occlusion, and features of meningitis. In particular, the high sensitivity of diffusion-weighted MR imaging in detecting intracranial abnormalities has been helpful in outbreaks. Although the coronaviruses causing the previous Severe Acute Respiratory Syndrome outbreak and the current coronavirus disease 19 pandemic are related, it is important to be aware of their similarities as well as potential differences. This review describes the neuroimaging appearances of selected zoonotic outbreaks so that neuroradiologists can better understand the current pandemic and potential future outbreaks.