INTRODUCTION: Omicron is the latest SARS-CoV-2 variant of concern, the pathogen that causes COVID-19. Since its emergence in late 2021, Omicron has displaced other circulating variants and caused successive waves of infection worldwide throughout 2022. Omicron is characterised by the rapid emergence of many subvariants and high rates of infection in people with vaccine- and/or infection induced immunity. This review article will consolidate current knowledge regarding Omicron subvariants, the role of boosters, and future vaccine development. METHOD: This narrative review is based on a literature search using PubMed. Search terms related to Omicron were used and priority was given to published peer-reviewed articles over pre-prints. RESULTS: Studies indicate that vaccinations and boosters are important to reduce disease severity, hospitalisation, and death from Omicron. A variety of factors, such as differing host factors, circulating variants, and forces of infection, can influence the benefit of repeated booster administration. Next-generation bivalent vaccines have now been approved in some countries including Singapore and have demonstrated the ability to induce broad variant protection. Future third-generation vaccines involving mucosal vaccines and/or pan-sarbecovirus vaccines may provide broader and longer-lasting protection. CONCLUSION Due to current high levels of vaccine- and infection-induced immunity, it is likely that rates of severe illness, hospitalisation, and death due to Omicron will continue to moderate. Nevertheless, the virus is ever-changing, and public health policies, especially those related to vaccinations, will also have to continually evolve and adapt as COVID-19 transitions to endemicity.
Humans ; SARS-CoV-2 ; COVID-19/prevention & control* ; Vaccines ; Hospitalization

INTRODUCTION: There is a paucity of information on the cytokine, complement, endothelial activation, and coagulation profiles of multisystem inflammatory syndrome in adults (MIS-A), a rare but serious complication following recovery from SARS-CoV-2 infection. We aim to examine the immune biomarker and coagulation profiles in association with the clinical presentation and course of MIS-A. METHOD: The clinical features of MIS-A patients admitted to our tertiary hospital were documented. Their levels of interleukin (IL)-1β, IL-6, IL-10, IL-17, IL-18, interferon-α (IFN-α), IFN-γ, interferon gamma-induced protein 10 (IP-10), tumour necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, complement activation product (complement 5a [C5a]), and endothelial biomarker intercellular adhesion molecule-1 (ICAM-1) levels were assayed. The haemostatic profile was assessed with standard coagulation testing and thromboelastography. RESULTS: Three male patients were diagnosed with MIS-A at our centre from January to June 2022 with a median age of 55 years. All had tested positive for SARS-CoV-2 12-62 days prior to MIS-A presentation, with gastrointestinal and cardiovascular systems as the most commonly involved. Levels of IL-6, IL-10, IL-18, IP-10 and MCP-1 were raised whereas IL-1β, IFN-α, IFN-γ, IL-17 and TNF-α remained normal. Markedly elevated levels of C-reactive protein (CRP), ferritin and ICAM-1 were present in all. C5a was elevated in 2 patients. A hypercoagulable state was demonstrated by raised levels of D-dimer, factor VIII, von Willebrand factor antigen, and ristocetin cofactor with corresponding raised parameters in thromboelastography in the 2 patients who had their coagulation profile assessed. CONCLUSION MIS-A patients demonstrate activation of pro-inflammatory cytokines, endotheliopathy, complement hyperactivation and hypercoagulability.
Humans ; Adult ; Male ; Middle Aged ; COVID-19/complications* ; Interleukin-10 ; Interleukin-18 ; Intercellular Adhesion Molecule-1 ; Interleukin-17 ; Chemokine CXCL10 ; Interleukin-6 ; SARS-CoV-2 ; Connective Tissue Diseases ; Hemostatics

INTRODUCTION: Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with a high mortality rate, though outcomes of the different lung compliance phenotypes are unclear. We aimed to measure lung compliance and examine other factors associated with mortality in COVID-19 patients with ARDS. METHODS: Adult patients with COVID-19 ARDS who required invasive mechanical ventilation at 8 hospitals in Singapore were prospectively enrolled. Factors associated with both mortality and differences between high (<40mL/cm H RESULTS: A total of 102 patients with COVID-19 who required invasive mechanical ventilation were analysed; 15 (14.7%) did not survive. Non-survivors were older (median 70 years, interquartile range [IQR] 67-75 versus median 61 years, IQR 52-66; CONCLUSION COVID-19 ARDS patients with higher compliance on the day of intubation and a longitudinal decrease over time had a higher risk of death.
COVID-19 ; Humans ; Lung Compliance ; Phenotype ; Respiratory Distress Syndrome/therapy* ; SARS-CoV-2

The coronavirus disease 2019 (COVID-19) is typically diagnosed by specific assays that detect viral nucleic acid from the upper respiratory tract; however, this may miss infections involving only the lower airways. Computed tomography (CT) has been described as a diagnostic modality in the COVID-19 diagnosis and treatment plan. We present a case series with virologically confirmed COVID-19 pneumonia. Variable CT features were observed: consolidation with ground-glass opacities, ground-glass opacities with subpleural reticular bands, and an anterior-posterior gradient of lung abnormalities resembling that of acute respiratory distress syndrome. Evolution of CT findings was observed in one patient, where there was interval resolution of bilateral lung consolidation with development of bronchiolectasis and subpleural fibrotic bands. While sensitive for detecting lung parenchymal abnormalities in COVID-19 pneumonia, the use of CT for initial diagnosis is discouraged and should be reserved for specific clinical indications. Interpretation of chest CT findings should be correlated with duration of symptoms to better determine the disease stage and aid in patient management.
Aged ; Betacoronavirus ; Coronavirus Infections ; diagnosis ; Diagnosis, Differential ; Female ; Humans ; Lung ; diagnostic imaging ; Male ; Middle Aged ; Pandemics ; Pneumonia, Viral ; diagnosis ; Tomography, X-Ray Computed ; methods

INTRODUCTION: Chest radiographs (CXRs) are widely used for the screening and management of COVID-19. This article describes the radiographic features of COVID-19 based on an initial national cohort of patients. METHODS: This is a retrospective review of swab-positive patients with COVID-19 who were admitted to four different hospitals in Singapore between 22 January and 9 March 2020. Initial and follow-up CXRs were reviewed by three experienced radiologists to identify the predominant pattern and distribution of lung parenchymal abnormalities. RESULTS: In total, 347 CXRs of 96 patients were reviewed. Initial CXRs were abnormal in 41 (42.7%) out of 96 patients. The mean time from onset of symptoms to CXR abnormality was 5.3 ± 4.7 days. The predominant pattern of lung abnormality was ground-glass opacity on initial CXRs (51.2%) and consolidation on follow-up CXRs (51.0%). Multifocal bilateral abnormalities in mixed central and peripheral distribution were observed in 63.4% and 59.2% of abnormal initial and follow-up CXRs, respectively. The lower zones were involved in 90.2% of initial CXRs and 93.9% of follow-up CXRs. CONCLUSION In a cohort of swab-positive patients, including those identified from contact tracing, we found a lower incidence of CXR abnormalities than was previously reported. The most common pattern was ground-glass opacity or consolidation, but mixed central and peripheral involvement was more common than peripheral involvement alone.
COVID-19 ; Humans ; Lung/diagnostic imaging* ; Radiography, Thoracic ; Retrospective Studies ; SARS-CoV-2 ; Singapore