Uptake of pneumococcal vaccines in older Australian adults before and after universal public funding of PCV13.

BACKGROUND: In 2020 Australia changed the funded universal older adult pneumococcal vaccination program from use of the 23-valent pneumococcal polysaccharide vaccine (PPV23) at age 65 to the 13-valent pneumococcal conjugate vaccine (PCV13) at age 70 years. We investigated uptake of both PCV13 and PPV23 in older adults before and after the program change. METHODS: We analysed a national dataset of records of patients attending general practices (GPs). We included regular attendees aged 65 or above in 2020. Cumulative uptake of PCV13 and monthly uptake of PPV23 was compared for the two periods before (January 2019 to June 2020) and after (July 2020 to May 2021) the program change on 1 July 2020, by age groups and presence of comorbid conditions. RESULTS: Our study included data from 192,508 patients (mean age in 2020: 75.1 years, 54.2 % female, 46.1 % with at least one comorbidity). Before July 2020, for all adults regardless of underlying comorbidities, the cumulative uptake of PCV13 was < 1 % but by May 2021, eleven months after the program changes, cumulative uptake of PCV13 had increased among those aged 70-79 years (without comorbidity: 16.3 %; with comorbidity: 21.1 %) and 80 + years (without comorbidity: 13.5 %; with comorbidity: 17.7 %), but not among those aged 65-69 years (without comorbidity: 1.3 %; with comorbidity: 3 %). Monthly uptake of PPV23 dropped following the program change across all age groups. CONCLUSIONS: Changes in uptake of PCV13 and PPV23 among those aged 70 + years were consistent with program changes. However, PCV13 uptake was still substantially lower in individuals aged 65-69 years overall and in those with comorbidities.

Estimates of Seasonal Influenza Burden That Could Be Averted by Improved Influenza Vaccines in the Australian Population Aged Under 65 Years, 2015-2019.

BACKGROUND: The interpretation of relative vaccine effectiveness (rVE) of improved influenza vaccines is complex. Estimation of burden averted is useful to contextualise their potential impact across different seasons. For the population aged under 65 years in Australia, this study estimated the additional morbidity and mortality that could be averted using improved influenza vaccines. METHODS: We used observed, season-specific (2015-2019) influenza notification and influenza-coded hospitalisation frequencies and published modelled estimates of influenza-associated hospitalisations and deaths that occurred under the prevailing influenza vaccination coverage scenario. After back-calculating to the estimated burden in the population without vaccination, we applied published standard influenza vaccine effectiveness and coverage estimates to calculate the burden potentially averted by standard and improved influenza vaccines. A plausible range of rVE values were used, assuming 50% coverage. RESULTS: The percentage point difference in absolute vaccine effectiveness (VE) of an improved vaccine compared to a standard vaccine is directly proportional to its rVE and inversely proportional to the effectiveness of the standard vaccine. The incremental burden averted by an improved vaccine is a function of both its difference in absolute VE and the severity of the influenza season. Assuming an rVE of 15% with 50% coverage, the improved vaccine was estimated to additionally avert 1517 to 12,641 influenza notifications, 287 to 1311 influenza-coded hospitalisations and 9 to 33 modelled all-cause influenza deaths per year compared to the standard vaccine. CONCLUSIONS: Improved vaccines can have substantial clinical and population impact, particularly when the effectiveness of standard vaccines is low, and burden is high.

The association between influenza vaccination uptake and influenza and pneumonia-associated deaths in the United States.

BACKGROUND: The influenza mortality burden has remained substantial in the United States (US) despite relatively high levels of influenza vaccine uptake. This has led to questions regarding the effectiveness of the program against this outcome, particularly in the elderly. The aim of this evaluation was to develop and explore a new approach to estimating the population-level effect of influenza vaccination uptake on pneumonia and influenza (P&I) associated deaths. METHODS: Using publicly available data we examined the association between state-level influenza vaccination and all-age P&I associated deaths in the US from the 2013-2014 influenza season to the 2018-2019 season. In the main model, we evaluated influenza vaccine uptake in all those age 6 months and older. We used a mixed-effects regression analysis with generalised least squares estimation to account for within state correlation in P&I mortality. RESULTS: From 2013-2014 through 2018-2019, the total number of all-age P&I related deaths during the influenza seasons was 480,111. The mean overall cumulative influenza vaccine uptake (age 6 months and older) across the states and years considered was 46.7%, with higher uptake (64.8%) observed in those aged ≥ 65 years. We found that overall influenza vaccine uptake (6 months and older) had a statistically significant protective association with the P&I death rate. This translated to a 0.33 (95% CI: 0.20, 0.47) per 100,000 population reduction in P&I deaths in the influenza season per 1% increase in overall influenza vaccine uptake. DISCUSSION: These results using a population-level statistical approach provide additional support for the overall effectiveness of the US influenza vaccination program. This reassurance is critical given the importance of ensuring confidence in this life saving program. Future research is needed to expand on our approach using more refined data.

Bayesian structural time series, an alternative to interrupted time series in the right circumstances.

OBJECTIVES: Compare two approaches to analyzing time series data-interrupted time series with segmented regression (ITS-SR) and Bayesian structural time series using the CausalImpact R package (BSTS-CI)-highlighting advantages, disadvantages, and implementation considerations. STUDY DESIGN AND SETTING: We analyzed electronic health records using each approach to estimate the antibiotic prescribing reduction associated with an educational program delivered to Australian primary care physicians between 2012 and 2017. Two outcomes were considered: antibiotics for upper respiratory tract infections (URTIs) and antibiotics of specified formulations. RESULTS: For URTI indication prescribing, average monthly prescriptions changes were estimated at -4,550; (95% confidence interval, -5,486 to -3,614) and -4,270; (95% credible interval, -5,934 to -2,626) for ITS-SR and BSTS-CI, respectively. Similarly for specified formulation prescribing, monthly average changes were estimated at -7,923; (95% confidence interval, -15,887 to 40) for ITS-SR and -20,269; (95% credible interval, -25,011 to -15,635) for BSTS-CI. CONCLUSION: Differing results between ITS-SR and BSTS-CI appear driven by divergent explanatory and outcome series trends. The BSTS-CI may be a suitable alternative to ITS-SR only if the explanatory series represent the secular trend of the outcome series before the intervention and are equally affected by exogenous or confounding factors. When appropriately applied, BSTS-CI provides an alternative to ITS with more readily interpretable Bayesian effect estimates.

Comparison of statistical methods for the early detection of disease outbreaks in small population settings.

Objectives: This study examines the performance of 6 aberration detection algorithms for the early detection of disease outbreaks in small population settings using syndrome-based early warning surveillance data collected by the Pacific Syndromic Surveillance System (PSSS). Although previous studies have proposed statistical methods for detecting aberrations in larger datasets, there is limited knowledge about how these perform in the presence of small numbers of background cases. Methods: To address this gap a simulation model was developed to test and compare the performance of the 6 algorithms in detecting outbreaks of different magnitudes, durations, and case distributions. Results: The study found that while the Early Aberration Reporting System-C1 algorithm developed by Hutwagner et al. outperformed others, no single approach provided reliable monitoring across all outbreak types. Furthermore, aberration detection approaches could only detect very large and acute outbreaks with any reliability. Conclusion: The findings of this study suggest that algorithm-based approaches to outbreak signal detection perform poorly when applied to settings with small numbers of background cases and should not be relied upon in these contexts. This highlights the need for alternative approaches for accurate and timely outbreak detection in small population settings, particularly those that are resource-constrained.

Effectiveness of influenza vaccination in reducing influenza-like illness and related antibiotic prescriptions in adults from a primary care-based case-control study.

BACKGROUND: Evidence on the effectiveness of influenza vaccine in preventing antibiotic prescriptions for influenza-like illness (ILI) in adults is limited. METHODS: A primary care-based case-control study was conducted to estimate influenza vaccine effectiveness (VE) against influenza-like illness (ILI) and antibiotic prescribing for ILI in adults aged ≥40 years. Cases were patients diagnosed with ILI from 1st June to 30th September in each year, 2015-2018; a subset of those with ILI prescribed antibiotics was also defined. Controls were patients attending a practice who did not receive an ILI diagnosis. Generalised estimating equations were used to calculate adjusted VE overall, by age (<65 versus ≥65 years) and comorbidity status. RESULTS: The number of ILI cases varied from 558 in 2018 to 2901 in 2017 and controls from 86618 in 2015 to 136763 in 2017. Over 4 years the pooled estimate of VE was 24% (95%CI, 11% to 34%) against ILI and 15% (95%CI, -3% to 29%) against antibiotic prescription for ILI. Influenza vaccine was effective in reducing ILI with an associated antibiotic prescriptions in patients aged <65 years (VE=23%, 95%CI, 3% to 38%) and if no comorbidities were recorded (VE=22%, 95%CI, 1% to 39%) but not in other subgroups. CONCLUSIONS: Influenza vaccine reduced the likelihood of antibiotic prescriptions for ILI in low-risk adults (40-64 years and those without comorbidities).

Modelled estimates of hospitalisations attributable to respiratory syncytial virus and influenza in Australia, 2009-2017.

BACKGROUND: Respiratory syncytial virus (RSV) and influenza are important causes of disease in children and adults. In Australia, information on the burden of RSV in adults is particularly limited. METHODS: We used time series analysis to estimate respiratory, acute respiratory infection, pneumonia and influenza, and bronchiolitis hospitalisations attributable to RSV and influenza in Australia during 2009 through 2017. RSV and influenza-coded hospitalisations in <5-year-olds were used as proxies for relative weekly viral activity. RESULTS: From 2009 to 2017, the estimated all-age average annual rates of respiratory hospitalisations attributable to RSV and seasonal influenza (excluding 2009) were 54.8 (95% confidence interval [CI]: 20.1, 88.8) and 87.8 (95% CI: 74.5, 97.7) per 100,000, respectively. The highest estimated average annual RSV-attributable respiratory hospitalisation rate per 100,000 was 464.2 (95% CI: 285.9, 641.2) in <5-year-olds. For seasonal influenza, it was 521.6 (95% CI: 420.9, 600.0) in persons aged ≥75 years. In ≥75-year-olds, modelled estimates were approximately eight and two times the coded estimates for RSV and seasonal influenza, respectively. CONCLUSIONS: RSV and influenza are major causes of hospitalisation in young children and older adults in Australia, with morbidity underestimated by hospital diagnosis codes.

Global variation in early epidemic growth rates and reproduction number of seasonal influenza.

BACKGROUND: Little is known about global variation in early epidemic growth rates and effective reproduction numbers (Re) of seasonal influenza. We aimed to estimate global variation in Re of influenza type A and B during a single period. METHODS: Country influenza detection time series from September 2017 through January 2019 were obtained from an international database. Type A and B epidemics by country were selected on the basis of Re estimates for a five-week moving window, advanced by week. Associations of Re with absolute latitude, human development index, percent of the population aged <15 years, and percent of those living in rural areas in each country were assessed. RESULTS: Time series were included for 119 of 169 available countries. There were 100 countries with influenza A and 79 with B epidemics. Median Re for both influenza A and B epidemics was 1.23 (ranges: A 1.10, 1.60; B 1.06, 1.58). Re of influenza B but not A was independently associated with absolute latitude, increasing by 0.022 (95% confidence interval 0.002, 0.043) per 10 degrees. CONCLUSION: The Re of influenza A and B were similar. Only the Re of influenza B was associated with country characteristics, which was increasing with distance from the equator. The approach may be suitable for continuous Re surveillance.

Effectiveness of Influenza Vaccination in Reducing Subsequent Antibiotic Prescribing in Young Children Attending Australian General Practices-A Case-Control Study.

BACKGROUND: Vaccination against influenza may reduce antibiotic use, but data are limited and imprecise. METHODS: We conducted a case-control study using deidentified data from a large national primary care database to evaluate antibiotic prescribing changes following influenza vaccination in children 1-4 years old attending primary care in the Australian 2018 and 2019 influenza seasons. Cases were prescribed ß-lactam or macrolide antibiotics during the influenza season and controls were not. Influenza vaccination was documented in the medical records. Adjusted odds ratios for antibiotic prescribing according to influenza vaccination status were estimated using generalized estimating equations, controlling for age, asthma diagnosis, other vaccinations, practice visit frequency, and attendance week. RESULTS: In 2018, 11 282 cases and 32 020 controls were eligible, and in 2019, 12 705 cases and 36 858 controls. Antibiotic prescriptions were less likely in vaccinated participants in 2018 (aOR, 0.65; 95% CI, 0.62-0.69) and 2019 (aOR, 0.78; 95% CI, 0.73-0.82) and did not vary by age, the number of GP visits, or prior prescribing of antibiotics. In the subgroup of children vaccinated in the preceding season, influenza vaccination was not associated with a reduction in antibiotic use (2018-aOR, 1.12; 95% CI, 0.90-1.39; 2019-aOR, 1.30; 95% CI, 1.16-1.46). From our estimates, potentially 100 000 antibiotic prescriptions could be avoided annually in Australia if all children in this age range were vaccinated. CONCLUSIONS: Influenza vaccination may substantially reduce antibiotic prescribing among young children. This effect should be considered in the overall assessment of the costs and benefits of childhood influenza vaccination programs.

RSV Epidemiology in Australia Before and During COVID-19.

COVID-19 public health measures altered respiratory syncytial virus (RSV) epidemiology. We examined age-stratified trends in RSV-related disease in Australian children in 2020 compared with previous years.

Influenza-associated mortality in Australia, 2010 through 2019: High modelled estimates in 2017.

INTRODUCTION: In Australia, the 2017 and 2019 influenza seasons were severe. High-dose or adjuvanted vaccines were introduced for ≥65 year-olds in 2018. AIM: To compare influenza-associated mortality in 2017 and 2019 with the average for 2010-2019. METHODS: We used time series modelling to obtain estimates of influenza-associated death rates for influenza A(H1N1)pdm09, A(H3N2) and B in Australia, in persons of all ages and <65, 65-74 and ≥75 years. Estimates were made for pneumonia and influenza (P&I, 2010-2018), respiratory (2010-2018), and all-cause outcomes (2010-2019). RESULTS: During 2010 through 2018 (and 2019 for all-cause), influenza was estimated to be associated with an annual average of 2.1 (95% confidence interval (CI) 1.9, 2.4), 4.0 (95% CI 3.4, 4.6), and 11.6 (95% CI 8.4, 15.0) P&I, respiratory and all-cause deaths per 100,000 population, respectively. Influenza A(H1N1)pdm09 was estimated to be associated with less than one quarter of influenza-associated P&I and respiratory deaths, while A(H3N2) and B were each estimated to contribute approximately equally to the remaining influenza-associated deaths. In 2017, the respective rates were 7.8 (95% CI 7.1, 8.4), 12.3 (95% CI 10.9, 13.6) and 26.0 (95% CI 20.8, 32.0) per 100,000. In 2019, the all-cause estimate was 20.8 (95% CI 14.9, 26.7) per 100,000. CONCLUSIONS: Seasonal influenza continues to be associated with substantial mortality in Australia, with at least double the average occurring in 2017. Age-specific monitoring of vaccine effectiveness is needed in Australia to understand higher mortality seasons.

Role of presymptomatic transmission of COVID-19: evidence from Beijing, China.

BACKGROUND: The presymptomatic transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been documented in limited clusters, and it is predicted through modelling. However, there is a lack of evidence from observations with a large sample size. METHODS: We used data from meticulous contact tracing of people exposed to cases of SARS-CoV-2 to estimate the proportion of cases that result from the presymptomatic transmission of the virus in Beijing during January 2020 and February 2020. RESULTS: The results showed that presymptomatic transmission occurred in at least 15% of 100 secondary COVID-19 cases. The earliest presymptomatic contact event occurred 5 days prior to the index case's onset of symptoms, and this occurred in two clusters. CONCLUSIONS: The finding suggested that the contact tracing period should be earlier and highlighted the importance of preventing transmission opportunities well before the onset of symptoms.

Evaluation of the Indonesian Early Warning Alert and Response System (EWARS) in West Papua, Indonesia.

Background: The Early Warning and Response System (EWARS) is Indonesia's national syndromic and early warning surveillance system for the rapid detection of infectious diseases and outbreaks. We evaluated EWARS in the remote West Papua province of Indonesia. Methods: Structured telephone interviews were conducted with 11 key informants from West Papuan health services. EWARS data were analysed for usefulness of reporting. Results: Most respondents reported that EWARS is important and useful in improving early detection of outbreaks. The system has led to increased disease control coordination among health jurisdictional levels in the province. However, respondents noted that the limited number of districts involved in the system affected representativeness, and some stated that only about 30-35% of districts in each regency were involved and trained in EWARS reporting, partly owing to lack of a mobile telephone network. Barriers to complete reporting and response to alerts included limited human and funding resources for surveillance, lack of epidemiological training, and technical limitations imposed by limited internet and mobile communication infrastructure in this remote region. Conclusion: Great progress has been made in integrating West Papua into a nationally consistent disease and outbreak detection system. Strategies for addressing barriers resulting from remoteness, constrained human, funding and laboratory resources, lack of training, and limited internet and communications infrastructure are needed if EWARS in West Papua is to advance.

Prediction of seasonal patterns of porcine reproductive and respiratory syndrome virus RNA detection in the U.S. swine industry.

We developed a model to predict the cyclic pattern of porcine reproductive and respiratory syndrome virus (PRRSV) RNA detection by reverse-transcription real-time PCR (RT-rtPCR) from 4 major swine-centric veterinary diagnostic laboratories (VDLs) in the United States and to use historical data to forecast the upcoming year's weekly percentage of positive submissions and issue outbreak signals when the pattern of detection was not as expected. Standardized submission data and test results were used. Historical data (2015-2017) composed of the weekly percentage of PCR-positive submissions were used to fit a cyclic robust regression model. The findings were used to forecast the expected weekly percentage of PCR-positive submissions, with a 95% confidence interval (CI), for 2018. During 2018, the proportion of PRRSV-positive submissions crossed 95% CI boundaries at week 2, 14-25, and 48. The relatively higher detection on week 2 and 48 were mostly from submissions containing samples from wean-to-market pigs, and for week 14-25 originated mostly from samples from adult/sow farms. There was a recurring yearly pattern of detection, wherein an increased proportion of PRRSV RNA detection in submissions originating from wean-to-finish farms was followed by increased detection in samples from adult/sow farms. Results from the model described herein confirm the seasonal cyclic pattern of PRRSV detection using test results consolidated from 4 VDLs. Wave crests occurred consistently during winter, and wave troughs occurred consistently during the summer months. Our model was able to correctly identify statistically significant outbreak signals in PRRSV RNA detection at 3 instances during 2018.

Estimated hospitalisations attributable to seasonal and pandemic influenza in Australia: 2001- 2013.

BACKGROUND: Influenza continues to cause seasonal epidemics and pandemics in humans. The burden of influenza is underestimated by traditional laboratory-based surveillance, and modelled estimates are required for influenza-attributable morbidity and mortality. We aimed to estimate the influenza-attributable hospitalisation in Australia, by influenza type. METHODS: A generalised-additive regression model was used to estimate type- and age-specific influenza-attributable hospitalisation rates per 100,000 population by principal diagnosis in Australia, from 2001 through 2013. Weekly counts of laboratory-confirmed influenza notifications and by type, influenza A and B were used as covariates in the model. Main principal diagnosis categories of interest were influenza and pneumonia and respiratory admissions. A smoothing spline was used to control for unmeasured time varying factors. Results for 2009, in which the pandemic influenza A(H1N1)pdm09 virus circulated, were not included in annual averages and are reported separately. RESULTS: During the study period, the estimated annual average, all-age, annual respiratory hospitalisation rates attributable to seasonal influenza type A, B and total influenza were 45.4 (95% CI: 34.9, 55.9), 32.6 (95% CI: 22.8, 42.4), and 76.9 (95% CI: 73.6, 80.2) per 100,000 population, respectively. During 2009, the estimated total pandemic influenza-attributable, all-age, respiratory hospitalisation rate was 56.1 (95% CI: 47.4, 64.9) per 100,000. Older adults (≥85 years of age) experienced the highest influenza-attributable hospitalisation rates for both seasonal and 2009 pandemic influenza. Collinearity between influenza A and B time series in some years limited the ability of the model to resolve differences in influenza attribution between the two virus types. CONCLUSION: Both seasonal and pandemic influenza caused considerable morbidity in Australia during the years studied, particularly among older adults. The pandemic hospitalisation rate in 2009 was lower than the average overall annual rate for seasonal influenza, but young to middle aged adults experience a hospitalisation rate similar to that of severe seasonal influenza.

Retrospective observational cohort study of out-of-hospital cardiac arrest outcomes in Tasmania 2010-2014.

OBJECTIVE: This study aims to present overall survival rates to hospital discharge for out-of-hospital cardiac arrest (OHCA) in Tasmania and to identify predictors of survival. METHODS: A retrospective observational cohort study was undertaken from 1 January 2010 to 31 December 2014. A probabilistically linked data set was created from paramedic electronic medical records and hospital patient records. Logistic regression was used to assess factors associated with survival of OHCA. RESULTS: During the study, 2949 incidents of OHCA were reviewed and 1146 had emergency management provided, with an overall survival rate to hospital discharge of 135 (12%). A number of independent factors are associated with improved outcomes including if the initial presenting cardiac rhythm was either ventricular fibrillation or ventricular tachycardia (adjusted odds ratio [OR] 8.75, 95% confidence interval [CI] 5.15-14.89) (P < 0.0001) relative to those who were found in a non-shockable rhythm. Another factor was age group (overall P < 0.001). Those aged 85+ years had a reduced overall survival rate (2.9%), which was lower than those <16 years of age (OR 0.37, 95% CI 0.07-1.94; adjusted OR 0.38, CI 0.03-1.00) (P < 0.001). The odds of surviving OHCA decreased by 9% for every minute defibrillation of a shockable rhythm was delayed were witnessed by a bystander (OR 0.90, 95% CI 0.85-0.95). CONCLUSION: Time to defibrillation for witnessed arrests, other than paramedic witnessed arrest was associated with better overall survival rates than unwitnessed OHCA. Further factors such as the event being of cardiac aetiology, bystander cardio-pulmonary resuscitation performed, initial presenting cardiac rhythm of ventricular fibrillation or ventricular tachycardia and decreasing age were all associated with increased probability of survival.

A model of influenza infection and vaccination in children aged under 5 years in Beijing, China.

BACKGROUND: Children aged under 5 years are particularly vulnerable to influenza infection. In this study, we aim to estimate the number and incidence of influenza among young children and estimate the impact of childhood vaccination in different scenarios from 2013/14 to 2016/17 seasons. METHODS: The number and incidence rate of influenza infections among children aged under 5 years in Beijing was estimated by scaling up observed surveillance data. Then, we used a susceptible-exposed-infected-recovery (SEIR) model to reproduce the weekly number of influenza infections estimated in Beijing during the study seasons, and to estimate the number and proportion of influenza-attributed medically attended acute respiratory infections (I-MAARI) averted by vaccination in each season. Finally, we evaluated the impact of alternative childhood vaccination programs with different coverage and speed of vaccine distribution. RESULTS: The estimated average annual incidence of influenza in children aged under 5 years was 33.9% (95% confidence interval (CI): 27.5%, 47.2%) during the study period. With the actual coverage during the included seasons at around 2.9%, an average of 3.9% (95%CI: 3.5%, 4.4%) I-MAARI was reduced compared to a no-vaccination scenario. Reaching 20%, 40%, 50%, 60%, 80% and 100% vaccine coverage would lead to an overall I-MAARI reduction of 25.3%, 42.7%, 51.9%, 57.0%, 65.3% and 71.2%. At 20% coverage scenario, an average of 28.8% I-MAARI will be prevented if intensive vaccination implemented in 2 months since the vaccine released. CONCLUSION: In Beijing, the introduction of a program for vaccinating young children, even at relatively low vaccine coverage rates, would considerably reduce I-MAARI, particularly if the vaccines can be quickly delivered.

Impact of seasonal influenza on polyclinic attendances for upper respiratory tract infections in Singapore.

PURPOSE: The burden of influenza on primary health-care services is not well established in tropical countries, where there are no clearly defined influenza seasons. We aimed to estimate the association between influenza infection activity and polyclinic attendance rates for upper respiratory tract infections (URTIs) in the Singapore population. METHODS: We used generalized additive time series models to estimate the association between the proportion of respiratory tests positive for influenza infection in Singapore reported to the World Health Organization every week, and the population rate of polyclinic attendances in Singapore for physician-diagnosed URTI, which includes influenza-like illness (ILI), for six years from 2012 through 2017. Where data were available, we controlled for other infections that can cause fever or respiratory symptoms. RESULTS: Influenza, dengue fever and chickenpox (varicella) were positively associated with acute URTI polyclinic attendances. The estimated URTI polyclinic attendance rates attributable to influenza, dengue fever and chickenpox were 618.9 (95% confidence interval [CI]: 501.6-736.3), 153.3 (95% CI: 16.5-290.2) and 1751.5 (95% CI: 1246.3-2256.8) per 100 000 population per year, respectively. CONCLUSION: Influenza poses a considerable burden on primary health-care services in Singapore. However, a substantial number of polyclinic attendances due to febrile infections such as dengue fever and chickenpox appear to be recorded as URTI in the polyclinic database. These associations require further investigation.

Effect of overseas parental employment migration on healthcare seeking for common childhood illnesses and nutritional status among left-behind young children: A systematic review.

We aimed to examine the available evidence on the impact of overseas parental migration on healthcare seeking for common childhood illnesses and the nutritional status of children left-behind under five years of age. A systematic review of English language articles was conducted on PubMed, MEDLINE and EMBASE, supplemented by a manual search of grey literature and reference lists. There were no studies examining the association between overseas parental migration and healthcare seeking for common childhood illnesses. We found three cross-sectional surveys examining the association with an indicator of nutritional status. We observed mixed findings from the available studies. The results indicated that children left-behind may have positive, negative or null effects on their nutritional status. There was insufficient information available to draw conclusions on the magnitude and direction of the association between overseas parental migration and its effect on either healthcare seeking for common childhood illnesses or the nutritional status of left-behind children. The association, if any, may be context or country dependent. Prospective studies are needed to address this important knowledge gap.