Infection In Singapore Research Articles

The attributable mortality, length of stay, and health care costs of methicillin-resistant Staphylococcus aureus infections in Singapore

ObjectivesWe used a multi-state model, which mitigates time-dependent bias, to estimate the mortality, length of stay (LOS), and costs of methicillin-resistant Staphylococcus aureus (MRSA) infections in Singapore. MethodsWe conducted a retrospective study in a hospital in Singapore from 2018 to 2022. Patients with MRSA infections were matched 1:1:3 to patients with MRSA colonization and patients without MRSA by age, gender, specialty, and intensive care admission, respectively. A multi-state model was used to derive excess LOS and mortality hazard ratios. The attributable cost of infections was estimated in 2022 Singapore dollars (SGDs) from the health care perspective. ResultsWe matched 536 patients with MRSA infections to 536 patients with MRSA colonization, and to 1608 patients without MRSA. The excess LOS due to MRSA infection was 2.11 (95% confidence interval [CI] 2.05-2.17) days compared with MRSA colonization and 3.75 (95% CI 3.69-3.80) days compared with no MRSA, which translated to an excess cost of SGD $1825 and SGD $3238, respectively. Of the different MRSA infection types, pneumonia had the highest mortality risk (hazard ratio 4.13; 95% CI 2.28-7.50) compared with patients without MRSA. ConclusionsMRSA infections increased hospital LOS and health care costs in Singapore. Our estimates can inform future economic analyses of management strategies against MRSA.

Differences in virus and immune dynamics for SARS-CoV-2 Delta and Omicron infections by age and vaccination histories

Vaccination against COVID-19 was integral to controlling the pandemic that persisted with the continuous emergence of SARS-CoV-2 variants. Using a mathematical model describing SARS-CoV-2 within-host infection dynamics, we estimate differences in virus and immunity due to factors of infecting variant, age, and vaccination history (vaccination brand, number of doses and time since vaccination). We fit our model in a Bayesian framework to upper respiratory tract viral load measurements obtained from cases of Delta and Omicron infections in Singapore, of whom the majority only had one nasopharyngeal swab measurement. With this dataset, we are able to recreate similar trends in URT virus dynamics observed in past within-host modelling studies fitted to longitudinal patient data.We found that Omicron had higher R0,within values than Delta, indicating greater initial cell-to-cell spread of infection within the host. Moreover, heterogeneities in infection dynamics across patient subgroups could be recreated by fitting immunity-related parameters as vaccination history-specific, with or without age modification. Our model results are consistent with the notion of immunosenescence in SARS-CoV-2 infection in elderly individuals, and the issue of waning immunity with increased time since last vaccination. Lastly, vaccination was not found to subdue virus dynamics in Omicron infections as well as it had for Delta infections.This study provides insight into the influence of vaccine-elicited immunity on SARS-CoV-2 within-host dynamics, and the interplay between age and vaccination history. Furthermore, it demonstrates the need to disentangle host factors and changes in pathogen to discern factors influencing virus dynamics. Finally, this work demonstrates a way forward in the study of within-host virus dynamics, by use of viral load datasets including a large number of patients without repeated measurements.

Study protocol: infectious diseases consortium (I3D) for study on integrated and innovative approaches for management of respiratory infections: respiratory infections research and outcome study (RESPIRO)

BackgroundCommunity-acquired respiratory infections are a leading cause of illness and death globally. The aetiologies of community-acquired pneumonia remain poorly defined. The RESPIRO study is an ongoing prospective observational cohort study aimed at developing pragmatic logistical and analytic platforms to accurately identify the causes of moderate-to-severe community-acquired pneumonia in adults and understand the factors influencing disease caused by individual pathogens. The study is currently underway in Singapore and has plans for expansion into the broader region.MethodsRESPIRO is being conducted at three major tertiary hospitals in Singapore. Adults hospitalised with acute community-acquired pneumonia or lower respiratory tract infections, based on established clinical, laboratory and radiological criteria, will be recruited. Over the course of the illness, clinical data and biological samples will be collected longitudinally and stored in a biorepository for future analysis.DiscussionThe RESPIRO study is designed to be hypothesis generating, complementary to and easily integrated with other research projects and clinical trials. The detailed clinical database and biorepository will yield insights into the epidemiology and outcomes of community-acquired lower respiratory tract infections in Singapore and the surrounding region and offers the opportunity to deeply characterise the microbiology and immunopathology of community-acquired pneumonia.

Techniques for Continuous Catheter Irrigation of a Septic Metacarpophalangeal Joint.

Septic arthritis of the metacarpophalangeal joint (MCPJ) compromises 9% of hand infections in Singapore. Common surgical treatment is open arthrotomy and joint washout. The wound is often left open for drainage postoperatively. Repeated debridement and secondary closure are frequently needed after the index surgery. We describe a method of continuous catheter irrigation of septic MCPJ joint using an infant feeding catheter. This method provides great infection clearance to avoid repeated debridement and allows primary closure of the wound to avoid secondary closure. This method also significantly reduces postoperative pain so that to facilitate early mobilization of the joint, which is crucial for functional recovery. We illustrate the techniques of this procedure and key points of postoperative management in the ward with case examples to demonstrate its simplicity, safety, and efficacy in treating MCPJ septic arthritis.

733. The attributable mortality, length of stay, and healthcare costs of methicillin-resistant Staphylococcus aureus infections in Singapore

Abstract Background Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are known to compromise patient outcomes and increase healthcare costs. Previous evidence on the prolongation of length of stay due to MRSA infections in Singapore is limited by methodology, including time-dependent bias. We used a multistate model to estimate the expected attributable mortality, length of stay, and healthcare costs of MRSA infections in Singapore. Methods We conducted a retrospective case-cohort study in patients admitted to a Singapore tertiary hospital from 2018 – 2022. Patients with MRSA infections were matched to those without infections in a 1: 3 ratio, by age and admitting specialty. We used a multistate model to derive excess length of stay (Fig 1). Attributable cost of MRSA infections from the healthcare perspective (in 2023 Singapore dollar) was estimated by multiplying excess length of stay with the monetary value of a bed-day and MRSA incidence. Cox regression with adjustment of confounders was used to derive hazard ratios (HR) for mortality estimates. Results We matched 752 patients with MRSA infections to 2,256 patients without MRSA infections. The most common MRSA infections were skin and soft tissue infections (44.5%) and bacteraemia (18.9%). From the multistate model, the excess length of stay of a MRSA infection was 3.02 days (95% CI, 1.90 – 4.13 days). This translated to an excess healthcare cost of $594,128 (95% CI, $375,111– $813,144) per 100,000 admissions. MRSA skin and soft tissue infections had the longest length of excess stay (3.98 days; 95% CI, 2.50 – 5.46 days) and contributed most to health-care costs ($348,788 per 100,000 admissions; 95% CI, $219,099 – $478,476). After adjusting for potential confounders, the mortality risk of all MRSA infections compared to patients without infection was 1.40 (95% CI, 0.94 – 2.08). Among the different infection types, pneumonia (HR, 4.28; 95% CI, 1.25 – 14.57) and bacteraemia (HR, 2.60; 95% CI, 1.33 – 5.08) had the high mortality risk compared to patients without infection. Conclusion Patients with MRSA pneumonia and bacteraemia had highest mortality risk. MRSA skin and soft tissue infections were associated with the highest healthcare costs. Coordinated efforts to reduce these infections may save lives and free valuable resources. Disclosures Sean Whiteley, BSc (IT), Axomem: Board Member|Axomem: Fees received for service and software licenses

Variant-Specific IgA Protects Against Omicron Infection.

The emergence of rapidly evolving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, coupled with waning vaccine-induced immunity, has contributed to the rise of vaccine breakthrough infections. It is crucial to understand how vaccine-induced protection is mediated. We examined 2 prospective cohorts of mRNA vaccinated and boosted individuals during the Omicron wave of infection in Singapore. We found that individuals who remain uninfected over the follow-up period had a higher variant-specific IgA, but not IgG, antibody response at 1 month after booster vaccination, compared with individuals who became infected. We conclude that IgA may have a potential contributory role in protection against Omicron infection. Clinical Trials Registration . NCT05142319.

Higher Delta variant-specific neutralizing antibodies prevented infection in close contacts vaccinated with ancestral mRNA vaccines during the SARS-CoV-2 Delta wave

Identification of the risk factors and the high-risk groups which are most vulnerable is critical in COVID-19 disease management at a population level. Evaluating the efficacy of vaccination against infections is necessary to determine booster vaccination strategies for better protection in high-risk groups. In this study, we recruited 158 mRNA-vaccinated individuals during the Delta wave of SARS-CoV-2 infections in Singapore and examined the antibody profiles of infected individuals. We found that, despite high exposure due to communal living conditions in proximity, 4% of individuals (6/158) had PCR-confirmed infections and 96% (152/158) remained uninfected. Time-course analysis of the antibody profile at the start and the end of quarantine period showed Delta-specific boosting of anti-spike antibody response in 57% of the uninfected individuals (86/152). In the remaining 43% of the uninfected individuals (66/152) with no Delta-specific antibody boost, we found a higher Delta-specific antibody response at the start of quarantine period, which correlated with higher Delta pseudovirus neutralizing capacity. Our findings indicate that a higher basal variant-specific antibody response in the mRNA-vaccinated individuals contributes to better protection against infections by the new emerging SARS-CoV-2 variants.

Relative role of border restrictions, case finding and contact tracing in controlling SARS-CoV-2 in the presence of undetected transmission: a mathematical modelling study

BackgroundUnderstanding the overall effectiveness of non-pharmaceutical interventions to control the COVID-19 pandemic and reduce the burden of disease is crucial for future pandemic planning. However, quantifying the effectiveness of specific control measures and the extent of missed infections, in the absence of early large-scale serological surveys or random community testing, has remained challenging.MethodsCombining data on notified local COVID-19 cases with known and unknown sources of infections in Singapore with a branching process model, we reconstructed the incidence of missed infections during the early phase of the wild-type SARS-CoV-2 and Delta variant transmission. We then estimated the relative effectiveness of border control measures, case finding and contact tracing when there was no or low vaccine coverage in the population. We compared the risk of ICU admission and death between the wild-type SARS-CoV-2 and the Delta variant in notified cases and all infections.ResultsWe estimated strict border control measures were associated with 0.2 (95% credible intervals, CrI 0.04–0.8) missed imported infections per notified case between July and December 2020, a decline from around 1 missed imported infection per notified case in the early phases of the pandemic. Contact tracing was estimated to identify 78% (95% CrI 62–93%) of the secondary infections generated by notified cases before the partial lockdown in Apr 2020, but this declined to 63% (95% CrI 56–71%) during the lockdown and rebounded to 78% (95% CrI 58–94%) during reopening in Jul 2020. The contribution of contact tracing towards overall outbreak control also hinges on ability to find cases with unknown sources of infection: 42% (95% CrI 12–84%) of such cases were found prior to the lockdown; 10% (95% CrI 7–15%) during the lockdown; 47% (95% CrI 17–85%) during reopening, due to increased testing capacity and health-seeking behaviour. We estimated around 63% (95% CrI 49–78%) of the wild-type SARS-CoV-2 infections were undetected during 2020 and around 70% (95% CrI 49–91%) for the Delta variant in 2021.ConclusionsCombining models with case linkage data enables evaluation of the effectiveness of different components of outbreak control measures, and provides more reliable situational awareness when some cases are missed. Using such approaches for early identification of the weakest link in containment efforts could help policy makers to better redirect limited resources to strengthen outbreak control.

Air quality, meteorological variability and pediatric respiratory syncytial virus infections in Singapore

Respiratory syncytial virus (RSV) is an important cause of respiratory illness among children. While studies have focused on the air-quality and climate dependence of RSV infections, few have been undertaken in South-East Asia where the burden of respiratory illness is among the highest across the globe. This study aimed to determine the relationships between climatic factors and air quality with RSV infections among children in Singapore. We obtained all laboratory-confirmed reports of RSV infections in children below 5 years old from the largest public hospital specializing in pediatric healthcare in Singapore. We assessed the independent cumulative effects of air quality and meteorological factors on RSV infection risk using the Distributed Lag Non-Linear Model (DLNM) framework in negative binomial models adjusted for long-term trend, seasonality and changes in the diagnostic systems. We included 15,715 laboratory-confirmed RSV reports from 2009 to 2019. Daily maximum temperature exhibited a complex, non-linear association with RSV infections. Absolute humidity (Relative Risk, 90th percentile [RR90th percentile]: 1.170, 95% CI: [1.102, 1.242]) was positively associated with RSV risk. Higher levels of particulate matter of aerodynamic diameter of less than (i) 2.5 µm (PM2.5), (ii) 10 µm (PM10), carbon monoxide (CO) and sulfur dioxide (SO2) were associated with lower RSV infection risk. RSV infections exhibited both annual and within-year seasonality. Our findings suggest that falls in ambient temperature and rises in absolute humidity exacerbated pediatric RSV infection risk while increases in air pollutant concentrations were associated with lowered infection risk. These meteorological factors, together with the predictable seasonality of RSV infections, can inform the timing of mitigation measures aimed at reducing transmission.

National HIV programme testing recommendations.

In recognition of the morbidity and mortality associated with human immunodeficiency virus (HIV), the Joint United Nations Programme on HIV/acquired immunodeficiency syndrome (AIDS) (UNAIDS) aims to end the epidemic by setting and striving to achieve the ambitious 95-95-95 targets. However, Singapore is still not performing well in the first UNAIDS target. The National HIV Programme (NHIVP) developed this set of recommendations based on an adaptation of major international guidelines from the World Health Organization and the US Centers for Disease Control and Prevention. The goals of this recommendation are: (1) to increase the uptake of HIV testing; (2) to allow earlier detection and identification of individuals with unrecognised HIV infection; (3) to facilitate linkage to clinical services; and (4) reduce further transmission of HIV infection in Singapore.

Real-world impact of a subsidy decision of sofosbuvir-velpatasvir for treatment of chronic hepatitis C on clinical practice and patient outcomes.

Sofosbuvir-velpatasvir was recommended for subsidy to treat chronic hepatitis C in Singapore in 2018. We measured the impact of the subsidy decision on clinical practice and patient outcomes. Specifically, we looked at pre- and post-subsidy changes in the utilization and prescribing pattern of chronic hepatitis C treatment and the real-world clinical effectiveness. Utilization trends and prescribing patterns were assessed using aggregated drug utilization data from public hospitals' dispensing systems and clinical data from the national electronic health record database, respectively. An audit was conducted to evaluate sustained virological response rate 12 weeks post treatment (SVR12). Use of sofosbuvir-velpatasvir increased sharply since its subsidy listing and dropped subsequently, whereas the utilization of comparator drugs remained low. Prescribing rate of sofosbuvir-velpatasvir increased from 13.7% in the pre-subsidy period to 90.2% in the post-subsidy period; 39.1% of patients previously on pegylated interferon and ribavirin switched to sofosbuvir-velpatasvir following its subsidy listing. In the audit, 365 out of 375 patients (97.3% [95% confidence interval: 95.1-98.6%]) achieved SVR12. The subsidy decision led to increased accessibility to patients and intended changes in clinical practice. Sofosbuvir-velpatasvir was also clinically effective in the real world. These findings augur well for the continued eradication of chronic hepatitis C infection in Singapore.

“WE ARE ALL MIGRANT WORKERS”: COMMONALITY OF BANGLADESHI MIGRANTS’ EXPERIENCES IN SINGAPORE AMIDST COVID-19

The number of COVID-19 infections in Singapore has increased dramatically since January 2020, with tens of thousands of cases linked to clusters in migrant workers’ (MWs) dormitories. The government planned to isolate the dormitories, conduct COVID-19 tests regularly, and relocate symptomatic individuals into quarantine facilities in order to combat the spread. Despite this, the majority of them were locked in their dormitories, living in tight conditions where social distancing is a myth. This research explores how COVID-19 has impacted the lives of these workers in several ways and illustrates the experiences these migrants have during the pandemic. The emphasis is on low-skilled workers from Bangladesh, who are vulnerable to COVID-19 in a variety of ways. This study used the theory of commonality to explain the diverse experiences of Singapore employees. The data demonstrate the shared hardships of commonality they accepted during COVID-19. Apart from their families, they face a life of uncertainty and anguish in the dorms, stating that commonality is felt and embodied individually while collectively negotiated and enacted. Despite the fact that their lives are filled with uncertainty and worry, they are happy and comfortable in Singapore because of how the government has taken care of them during times of crisis.

Characterisation of Salmonella Enteritidis ST11 and ST1925 Associated with Human Intestinal and Extra-Intestinal Infections in Singapore.

Salmonella Enteritidis is a major foodborne pathogen worldwide. In this study, a total of 276 S. enteritidis isolates, collected between 2016 and 2017 from human, food and farm/slaughterhouse samples, were studied to enhance the understanding of the epidemiology of human salmonellosis in Singapore. Results showed all 276 isolates belonged either to ST1925 (70.3%) or ST11 (29.7%), with ST11 being significantly more frequent in extra-intestinal isolates and chicken isolates. Food isolates, most of which were from poultry, showed the highest prevalence of resistance (33–37%) against beta-lactams or beta-lactams/beta-lactamase inhibitor combination (ampicillin, piperacillin and ampicillin/sulbactam). The analysis showed the detection of genes associated with resistance to aminoglycoside genes (99.6%), tetracycline (55.1%), and beta-lactams (14.9%) of all isolates. Nine types of plasmids were found in 266 isolates; the most common incompatibility group profiles were IncFIB(S)-IncFII(S)-IncX1 (72.2%) and IncFIB(S)-IncFII(S) (15.8%). Most plasmid harbouring isolates from chicken (63.6%, 14/22) and from human (73.8%, 175/237) shared the same plasmid profile (IncFIB(S)-IncFII(S)-IncX1). SNP analysis showed clustering of several isolates from poultry food products and human isolates, suggesting phylogenetic relatedness among these isolates. Lastly, this study provides important epidemiological insights on the application of phenotypic and next-generation sequencing (NGS) tools for improved food safety and public health surveillance and outbreak investigation of S. enteritidis.

Accounting for the role of asymptomatic patients in understanding the dynamics of the COVID-19 pandemic: a case study from Singapore

Abstract Objectives To forecast the true growth of COVID-19 cases in Singapore after accounting for asymptomatic infections, we study and make modifications to the SEIR (Susceptible-Exposed-Infected-Recovered) epidemiological model by incorporating hospitalization dynamics and the presence of asymptomatic cases. We then compare the simulation results of our three epidemiological models of interest against the daily reported COVID-19 case counts during the time period from 23rd January to 6th April 2020. Finally, we compare and evaluate on the performance and accuracy of the aforementioned models’ simulations. Methods Three epidemiological models are used to forecast the true growth of COVID-19 case counts by accounting for asymptomatic infections in Singapore. They are the exponential model, SEIR model with hospitalization dynamics (SEIHRD), and the SEIHRD model with inclusion of asymptomatic cases (SEAIHRD). Results Simulation results of all three models reflect underestimation of COVID-19 cases in Singapore during the early stages of the pandemic. At a 40% asymptomatic proportion, we report basic reproduction number R 0 = 3.28 and 3.74 under the SEIHRD and SEAIHRD models respectively. At a 60% asymptomatic proportion, we report R 0 = 3.48 and 3.96 under the SEIHRD and SEAIHRD models respectively. Conclusions Based on the results of different simulation scenarios, we are highly confident that the number of COVID-19 cases in Singapore was underestimated during the early stages of the pandemic. This is supported by the exponential increase of COVID-19 cases in Singapore as the pandemic evolved.

Mortality in children hospitalised with respiratory syncytial virus infection in Singapore.

This study aimed to investigate the trend and seasonality of infection due to respiratory syncytial virus (RSV) at KK Women's and Children's Hospital (KKH) in Singapore and to examine the risk factors for mortality among children with RSV infection requiring admission to the paediatric intensive care unit (PICU). A retrospective study was conducted at KKH on children with RSV infections who were admitted to the PICU between January 2004 and December 2010. The medical records of children who died from RSV infections were reviewed. Linear regression was performed to determine the risk factors for RSV mortality. RSV infection was documented in 5,785 children during the study period; the infection was noted to be occurring throughout the year, with a small increase in prevalence between the months of June and August every year. Among 85 (1.5%) out of 5,785 children who were admitted to the PICU for RSV infection, 74 (1.3%) survived and 11 (0.2%) died. Multivariate logistic regression analysis showed that haemodynamically significant cardiac disease (odds ratio [OR] 12.2, 95% confidence interval [CI] 0.9-16.7, p = 0.05), immunodeficiency (OR 71.4, 95% CI 8.2-500, p < 0.001) and metabolic disease (OR 71.4, 95% CI 4.3-1,000, p = 0.003) were independent risk factors for mortality in RSV infections. Prematurity increased the risk of admission to the PICU but was not significantly associated with mortality. Children with haemodynamically significant cardiac disease, immunodeficiency and metabolic disease were at higher risk of death after hospitalisation for RSV-related illnesses. These children should be considered for palivizumab prophylaxis.

Flavivirus: From Structure to Therapeutics Development.

Flaviviruses are still a hidden threat to global human safety, as we are reminded by recent reports of dengue virus infections in Singapore and African-lineage-like Zika virus infections in Brazil. Therapeutic drugs or vaccines for flavivirus infections are in urgent need but are not well developed. The Flaviviridae family comprises a large group of enveloped viruses with a single-strand RNA genome of positive polarity. The genome of flavivirus encodes ten proteins, and each of them plays a different and important role in viral infection. In this review, we briefly summarized the major information of flavivirus and further introduced some strategies for the design and development of vaccines and anti-flavivirus compound drugs based on the structure of the viral proteins. There is no doubt that in the past few years, studies of antiviral drugs have achieved solid progress based on better understanding of the flavivirus biology. However, currently, there are no fully effective antiviral drugs or vaccines for most flaviviruses. We hope that this review may provide useful information for future development of anti-flavivirus drugs and vaccines.

Challenges, reorganisation and recovery of obstetrics and gynecology outpatient services during and after the COVID-19 pandemic in a tertiary hospital

: The coronavirus disease 2019 (COVID-19) infection was declared a pandemic by the World Health Organization (WHO) on 11 March 2020. As of 16 January 2021, the WHO reported a total of 92,506,811 cases globally, with 2,001,773 deaths. The total number of confirmed COVID-19 infections in Singapore reported by the Ministry of Health (MOH) as of 16 January 2021 is 59,054 cases with 270 active cases. As there is currently no cure for COVID-19 infection, the best management strategy remains prevention of transmission through public infection control measures and the recently introduced vaccination programs. Globally, healthcare institutions across multiple disciplines are actively taking measures to reduce their ambulatory outpatient load for low-risk conditions to avoid unnecessary clinic visits and hence reduce the risk of exposure and transmission. In this paper, we describe the challenges faced and the reorganisation of care in the outpatient Obstetrics and Gynaecology (O&G) service in the largest tertiary hospital and referral centre for O&G in Singapore during the COVID-19 outbreak. We also present the challenges we anticipated upon resumption of our services in the post-outbreak period, and discuss the novel strategies we implemented to cope with the increased number of cases expected. These strategies are aimed to improve the standard of patient care, whilst adhering to public infection control guidelines to ensure the safety of our patients and healthcare workers.

A time series analysis of the short-term association between climatic variables and acute respiratory infections in Singapore.

Acute respiratory infections (ARIs) are among the most common human illnesses globally. Previous studies that examined the associations between climate variability and ARIs or ARI pathogens have reported inconsistent findings. Few studies have been conducted in Southeast Asia to date, and the impact of climatic factors are not well-understood. This study aimed to investigate the short-term associations between climate variability and ARIs in Singapore. We obtained reports of ARIs from all government primary healthcare services from 2005 to 2019 and analysed their dependence on mean ambient temperature, minimum temperature and maximum temperature using the distributed lag non-linear framework. Separate negative binomial regression models were used to estimate the association between each temperature (mean, minimum, maximum temperature) and ARIs, adjusted for seasonality and long-term trend, rainfall, relative humidity, public holidays and autocorrelations. For temperature variables and relative humidity we reported cumulative relative risks (RRs) at 10th and 90th percentiles compared to the reference value (centered at their medians) with corresponding 95% confidence intervals (CIs). For rainfall we reported RRs at 50th and 90th percentiles compared to 0mm with corresponding 95% CIs. Statistically significant inverse S-curve shaped associations were observed between all three temperature variables (mean, minimum, maximum) and ARIs. A decrease of 1.1°C from the median value of 27.8°C to 26.7°C (10th percentile) in the mean temperature was associated with a 6% increase (RR: 1.06, 95% CI: 1.03 to 1.09) in ARIs. ARIs also increased at 23.9°C (10th percentile)compared to 24.9°C of minimum temperature (RR: 1.11, 95% CI: 1.07 to 1.16). The effect of maximum temperature for the same comparison (30.5°C vs 31.7°C) was non-significant (RR: 1.02, 95% CI: 0.99 to 1.05). An increase in ambient temperature to 28.9 °C (90th percentile) was associated with an 18% decrease (RR: 0.82, 95% CI: 0.80 to 0.83) in ARIs. Similarly, ARIs decreased with the same increase to 90th percentile in minimum (RR: 0.84, 95% CI: 0.80 to 0.87) and maximum (RR: 0.89, 95% CI: 0.86 to 0.93) temperatures. Rainfall was inversely associated with ARIs and displayed similar shape in all three temperature models. Relative humidity, on the other hand, exhibited a U-shaped relationship with ARIs. Our findings suggest that lower temperatures increase the risk of ARIs. Anticipated extreme weather events that reduce ambient temperature can be used to inform increased healthcare resource allocation for ARIs.

The effectiveness of public health interventions against COVID-19: Lessons from the Singapore experience.

In dealing with community spread of COVID-19, two active interventions have been attempted or advocated-containment, and mitigation. Given the extensive impact of COVID-19 globally, there is international interest to learn from best practices that have been shown to work in controlling community spread to inform future outbreaks. This study explores the trajectory of COVID-19 infection in Singapore had the government intervention not focused on containment, but rather on mitigation. In addition, we estimate the actual COVID-19 infection cases in Singapore, given that confirmed cases are publicly available. We developed a COVID-19 infection model, which is a modified SIR model that differentiate between detected (diagnosed) and undetected (undiagnosed) individuals and segments total population into seven health states: susceptible (S), infected asymptomatic undiagnosed (A), infected asymptomatic diagnosed (I), infected symptomatic undiagnosed (U), infected symptomatic diagnosed (E), recovered (R), and dead (D). To account for the infection stages of the asymptomatic and symptomatic infected individuals, the asymptomatic infected individuals were further disaggregated into three infection stages: (a) latent (b) infectious and (c) non-infectious; while the symptomatic infected were disaggregated into two stages: (a) infectious and (b) non-infectious. The simulation result shows that by the end of the current epidemic cycle without considering the possibility of a second wave, under the containment intervention implemented in Singapore, the confirmed number of Singaporeans infected with COVID-19 (diagnosed asymptomatic and symptomatic cases) is projected to be 52,053 (with 95% confidence range of 49,370-54,735) representing 0.87% (0.83%-0.92%) of the total population; while the actual number of Singaporeans infected with COVID-19 (diagnosed and undiagnosed asymptomatic and symptomatic infected cases) is projected to be 86,041 (81,097-90,986), which is 1.65 times the confirmed cases and represents 1.45% (1.36%-1.53%) of the total population. A peak in infected cases is projected to have occurred on around day 125 (27/05/2020) for the confirmed infected cases and around day 115 (17/05/2020) for the actual infected cases. The number of deaths is estimated to be 37 (34-39) among those infected with COVID-19 by the end of the epidemic cycle; consequently, the perceived case fatality rate is projected to be 0.07%, while the actual case fatality rate is estimated to be 0.043%. Importantly, our simulation model results suggest that there about 65% more COVID-19 infection cases in Singapore that have not been captured in the official reported numbers which could be uncovered via a serological study. Compared to the containment intervention, a mitigation intervention would have resulted in early peak infection, and increase both the cumulative confirmed and actual infection cases and deaths. Early public health measures in the context of targeted, aggressive containment including swift and effective contact tracing and quarantine, was likely responsible for suppressing the number of COVID-19 infections in Singapore.

The effects of maximum ambient temperature and heatwaves on dengue infections in the tropical city-state of Singapore – A time series analysis

BackgroundGlobal incidence of dengue has surged rapidly over the past decade. Each year, an estimated 390 million infections occur worldwide, with Asia-Pacific countries bearing about three-quarters of the global dengue disease burden. Global warming may influence the pattern of dengue transmission. While previous studies have shown that extremely high temperatures can impede the development of the Aedes mosquito, the effect of such extreme heat over a sustained period, also known as heatwaves, has not been investigated in a tropical climate setting. AimWe examined the short-term relationships between maximum ambient temperature and heatwaves and reported dengue infections in Singapore, via ecological time series analysis, using data from 2009 to 2018. MethodsWe studied the effect of two measures of extreme heat – (i) heatwaves and (ii) maximum ambient temperature. We used a negative binomial regression, coupled with a distributed lag nonlinear model, to examine the immediate and lagged associations of extreme temperature on dengue infections, on a weekly timescale. We adjusted for long-term trend, seasonality, rainfall and absolute humidity, public holidays and autocorrelation. ResultsWe observed an overall inhibitive effect of heatwaves on the risk of dengue infections, and a parabolic relationship between maximum temperature and dengue infections. A 1 °C increase in maximum temperature from 31 °C was associated with a 13.1% (Relative Risk (RR): 0.868, 95% CI: 0.798, 0.946) reduction in the cumulative risk of dengue infections over six weeks. Weeks with 3 heatwave days were associated with a 28.3% (RR: 0.717, 95% CI: 0.608, 0.845) overall reduction compared to weeks with no heatwave days. Adopting different heatwaves specifications did not substantially alter our estimates. ConclusionExtreme heat was associated with decreased dengue incidence. Findings from this study highlight the importance of understanding the temperature dependency of vector-borne diseases in resource planning for an anticipated climate change scenario.