Objective: Coronavirus disease (COVID-19) vaccinations have been shown to prevent infection with efficacies ranging from 50% to 95%. This study assesses the impact of vaccination on the clinical severity of COVID-19 during the second wave in Brunei Darussalam in 2021, which was due to the Delta variant. Methods: Patients included in this study were randomly selected from those who were admitted with COVID-19 to the National Isolation Centre between 7 August and 6 October 2021. Cases were categorized as asymptomatic, mild (symptomatic without pneumonia), moderate (pneumonia), severe (needing supplemental oxygen therapy) or critical (needing mechanical ventilation) but for statistical analysis purposes were dichotomized into asymptomatic/mild or moderate/severe/critical cases. Univariate and multivariable analyses were conducted to identify risk factors associated with moderate/severe/critical disease. Propensity score-matched analysis was also performed to evaluate the impact of vaccination on disease severity. Results: The study cohort of 788 cases (mean age: 42.1 + 14.6 years; 400 males) comprised 471 (59.8%) asymptomatic/mild and 317 (40.2%) moderate/severe/critical cases. Multivariable logistic regression analysis showed older age group (>45 years), diabetes mellitus, overweight/obesity and vaccination status to be associated with increased severity of disease. In propensity score-matched analysis, the relative risk of developing moderate/severe/critical COVID-19 for fully vaccinated (two doses) and partially vaccinated (one dose) cases was 0.33 (95% confidence interval [CI]: 0.16–0.69) and 0.62 (95% CI: 0.46–0.82), respectively, compared with a control group of non-vaccinated cases. The corresponding relative risk reduction (RRR) values were 66.5% and 38.4%, respectively. Vaccination was also protective against moderate/severe/critical disease in a subgroup of overweight/obese patients (RRR: 37.2%, P = 0.007). Discussion: Among those who contracted COVID-19, older age, having diabetes, being overweight/obese and being unvaccinated were significant risk factors for moderate/severe/critical disease. Vaccination, even partial, was protective against moderate/severe/critical disease.

Objective: Bacterial co-infections in cases of coronavirus disease 2019 (COVID-19) can lead to less favourable outcomes. The aim of this study was to determine the prevalence of primary bacterial co-infections among patients with COVID-19 in Brunei Darussalam. Methods: Seventy-one of 180 patients admitted to the National Isolation Centre between 9 March 2020 and 4 February 2021 were screened for primary bacterial co-infection (infection occurring <48 h from admission). We compared patients with a primary bacterial co-infection to those without. Results: Of the 71 screened patients, 8 (11.2%) had a primary bacterial co-infection (sputum 37.5% [6/16], blood 2.8% [1/36], urine 1.7% [1/60]), for a period prevalence rate of 4.4% (respiratory tract infection 3.3% [6/180], bloodstream 0.6% [1/180], urine 0.6% [1/180]) among all COVID-19 patients. Older age, presence of comorbidity, symptoms at admission (fever, dyspnoea, nausea/vomiting), abnormal chest X-ray (CXR) and more severe COVID-19 (P < 0.05) were associated with primary bacterial co-infection. Primary bacterial co-infection was also associated with development of secondary infection and death (all P < 0.05). Only one patient with primary bacterial co-infection died (methicillin-sensitive Staphylococcus aureus septicaemia and multiorgan failure). Conclusions: Our study showed that primary bacterial co-infection affected 4.4% of patients with COVID-19 in Brunei Darussalam. Older age, presence of comorbidity, symptoms and abnormal CXR at admission and more severe disease were associated with a primary bacterial co-infection. Lower respiratory tract infection was the most common co-infection.

Coronavirus disease (COVID-19) and tuberculosis (TB) coinfection is expected to become more common in countries where TB is endemic, and coinfection has been reported to be associated with less favourable outcomes. Knowing about the manifestations and outcomes of coinfection is important as COVID-19 becomes endemic. During the second wave of the COVID-19 pandemic in Brunei Darussalam, we encountered seven patients with COVID-19 and Mycobacterium coinfection. Cases of coinfection included three patients with newly diagnosed pulmonary Mycobacterium infection (two cases of pulmonary TB [PTB] and one case of Mycobacterium fortuitum infection) and four patients who were already being treated for TB (three cases of PTB and one case of TB lymphadenitis). Among the new cases, one had previously tested negative for PTB during a pre-employment medical fitness evaluation and had defaulted from follow up and evaluation. One case died: a 42-year-old man with diabetes mellitus, chronic kidney disease and hypertension who had severe COVID-19 and needed urgent dialysis and supplemental oxygen. All other patients recovered from COVID-19 and completed their TB treatment.