Lack of effectiveness of 13-valent pneumococcal conjugate vaccination against pneumococcal carriage density in Papua New Guinean infants

BACKGROUND

Papua New Guinea (PNG) introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in 2014, with administration at 1, 2, and 3 months of age. PCV13 has reduced or eliminated carriage of vaccine types in populations with low pneumococcal carriage prevalence, carriage density and serotype diversity. This study investigated PCV13 impact on serotype-specific pneumococcal carriage prevalence, density, and serotype diversity in PNG infants, who have some of the highest reported rates of pneumococcal carriage and disease in the world.

METHODS

Nasopharyngeal swabs were collected at 1, 4 and 9 months of age from PCV13-vaccinated infants (n = 57) and age-/season-matched, unvaccinated infants (at approximately 1 month, n = 53; 4 months, n = 57; 9 months, n = 52). Serotype-specific pneumococcal carriage density and antimicrobial resistance genes were identified by qPCR and microarray.

RESULTS

Pneumococci were present in 89% of swabs, with 60 different serotypes and four non-encapsulated variants detected. Multiple serotype carriage was common (47% of swabs). Vaccine type carriage prevalence was similar between PCV13-vaccinated and unvaccinated infants at 4 and 9 months of age. The prevalence of non-vaccine type carriage was also similar between cohorts, with non-vaccine types present in three-quarters of samples (from both vaccinated and unvaccinated infants) by 4 months of age. The median pneumococcal carriage density was high and similar at each age group (~7.0 log₁₀genome equivalents/mL). PCV13 had no effect on overall pneumococcal carriage density, vaccine type density, non-vaccine type density, or the prevalence of antimicrobial resistance genes.

CONCLUSION

PNG infants experience dense and diverse pneumococcal colonisation with concurrent serotypes from 1 month of age. PCV13 had no impact on pneumococcal carriage density, even for vaccine serotypes. The low prevalence of vaccine serotypes, high pneumococcal carriage density and abundance of non-vaccine serotypes likely contribute to the lack of PCV13 impact on carriage in PNG infants. Indirect effects of the infant PCV programs are likely to be limited in PNG. Alternative vaccines with broader coverage should be considered.

Levels of pneumococcal conjugate vaccine coverage and indirect protection against invasive pneumococcal disease and pneumonia hospitalisations in Australia: An observational study

BACKGROUND

There is limited empiric evidence on the coverage of pneumococcal conjugate vaccines (PCVs) required to generate substantial indirect protection. We investigate the association between population PCV coverage and indirect protection against invasive pneumococcal disease (IPD) and pneumonia hospitalisations among undervaccinated Australian children.

METHODS AND FINDINGS

Birth and vaccination records, IPD notifications, and hospitalisations were individually linked for children aged <5 years, born between 2001 and 2012 in 2 Australian states (New South Wales and Western Australia; 1.37 million children). Using Poisson regression models, we examined the association between PCV coverage, in small geographical units, and the incidence of (1) 7-valent PCV (PCV7)-type IPD; (2) all-cause pneumonia; and (3) pneumococcal and lobar pneumonia hospitalisation in undervaccinated children. Undervaccinated children received <2 doses of PCV at <12 months of age and no doses at ≥12 months of age. Potential confounding variables were selected for adjustment a priori with the assistance of a directed acyclic graph. There were strong inverse associations between PCV coverage and the incidence of PCV7-type IPD (adjusted incidence rate ratio [aIRR] 0.967, 95% confidence interval [CI] 0.958 to 0.975, p-value < 0.001), and pneumonia hospitalisations (all-cause pneumonia: aIRR 0.991 95% CI 0.990 to 0.994, p-value < 0.001) among undervaccinated children. Subgroup analyses for children <4 months old, urban, rural, and Indigenous populations showed similar trends, although effects were smaller for rural and Indigenous populations. Approximately 50% coverage of PCV7 among children <5 years of age was estimated to prevent up to 72.5% (95% CI 51.6 to 84.4) of PCV7-type IPD among undervaccinated children, while 90% coverage was estimated to prevent 95.2% (95% CI 89.4 to 97.8). The main limitations of this study include the potential for differential loss to follow-up, geographical misclassification of children (based on residential address at birth only), and unmeasured confounders.

CONCLUSIONS

In this study, we observed substantial indirect protection at lower levels of PCV coverage than previously described-challenging assumptions that high levels of PCV coverage (i.e., greater than 90%) are required. Understanding the association between PCV coverage and indirect protection is a priority since the control of vaccine-type pneumococcal disease is a prerequisite for reducing the number of PCV doses (from 3 to 2). Reduced dose schedules have the potential to substantially reduce program costs while maintaining vaccine impact.

Excess respiratory mortality and hospitalizations associated with influenza in Australia, 2007-2015

BACKGROUND

Influenza is the most common vaccine-preventable disease in Australia, causing significant morbidity and mortality. We assessed the burden of influenza across all ages in terms of influenza-associated mortality and hospitalizations using national mortality, hospital-discharge and influenza surveillance data.

METHODS

Influenza-associated excess respiratory mortality and hospitalization rates from 2007 to 2015 were estimated using generalized additive models with a proxy of influenza activity based on syndromic and laboratory surveillance data. Estimates were made for each age group and year.

RESULTS

The estimated mean annual influenza-associated excess respiratory mortality was 2.6 per 100 000 population [95% confidence interval (CI): 1.8, 3.4 per 100 000 population]. The excess annual respiratory hospitalization rate was 57.4 per 100 000 population (95% CI: 32.5, 82.2 per 100 000 population). The highest mortality rates were observed among those aged ≥75 years (35.11 per 100 000 population; 95% CI: 19.93, 50.29 per 100 000 population) and hospitalization rates were also highest among older adults aged ≥75 years (302.95 per 100 000 population; 95% CI: 144.71, 461.19 per 100 000 population), as well as children aged <6 months (164.02 per 100 000 population; 95% CI: -34.84, 362.88 per 100 000 population). Annual variation was apparent, ranging from 1.0 to 3.9 per 100 000 population for mortality and 24.2 to 94.28 per 100 000 population for hospitalizations. Influenza A contributed to almost 80% of the average excess respiratory hospitalizations and 60% of the average excess respiratory deaths.

CONCLUSIONS

Influenza causes considerable burden to all Australians. Expected variation was observed among age groups, years and influenza type, with the greatest burden falling to older adults and young children. Understanding the current burden is useful for understanding the potential impact of mitigation strategies, such as vaccination.

Childhood vaccination coverage in Australia: an equity perspective

BACKGROUND

This study describes trends in social inequities in first dose measles-mumps-rubella (MMR1) vaccination coverage in Western Australia (WA) and New South Wales (NSW). Using probabilistically-linked administrative data for 1.2 million children born between 2002 and 2011, we compared levels and trends in MMR1 vaccination coverage measured at age 24 months by maternal country of birth, Aboriginal status, maternal age at delivery, socio-economic status, and remoteness in two states.

RESULTS

Vaccination coverage was 3-4% points lower among children of mothers who gave birth before the age of 20 years, mothers born overseas, mothers with an Aboriginal background, and parents with a low socio-economic status compared to children that did not belong to these social groups. In both states, between 2007 and 2011 there was a decline of 2.1% points in MMR1 vaccination coverage for children whose mothers were born overseas. In 2011, WA had lower coverage among the Aboriginal population (89.5%) and children of young mothers (89.3%) compared to NSW (92.2 and 92.1% respectively).

CONCLUSION

Despite overall high coverage of MMR1 vaccination, coverage inequalities increased especially for children of mothers born overseas. Strategic immunisation plans and policy interventions are important for equitable vaccination levels. Future policy should target children of mothers born overseas and Aboriginal children.

Impact of Coronavirus Disease 2019 Public Health Measures on Detections of Influenza and Respiratory Syncytial Virus in Children During the 2020 Australian Winter

Public health measures targeting coronavirus disease 2019 have potential to impact transmission of other respiratory viruses. We found 98.0% and 99.4% reductions in respiratory syncytial virus and influenza detections, respectively, in Western Australian children through winter 2020 despite schools reopening. Border closures have likely been important in limiting external introductions.

Predictors of hospital readmission in infants less than 3 months old

AIM

To examine rates and predictors of 7-day readmission in infants hospitalised before 3 months of age with infectious and non-infectious conditions.

METHODS

Retrospective population-based data-linkage study of 121 854 infants from a 5-year metropolitan birth cohort (2008-2012). Cox proportional hazard models were used to examine associations between infant and maternal factors with 7-day readmission.

RESULTS

A total of 11 669 (9.6%) infants were hospitalised at least once by 3 months of age (median 23 days old, 56% male) with 12 602 total index hospitalisations. Infection-related conditions accounted for 29.4% (n = 3705). Readmission within 7 days occurred after 4.8% of all index hospitalisations and 5.4% of infection-related hospitalisations. Age ≤21 days was the strongest readmission risk factor (hazard ratio 7.7 (95% confidence interval 4.7-12.7) compared to infants 61-90 days old). Other risk factors included shorter index hospitalisations, younger maternal age and multi-gravidity.

CONCLUSION

Hospitalisations and readmissions occur for many young infants. Risk factors for readmission should inform risk-based management guidelines.

Improving Influenza Vaccination in Children With Comorbidities: A Systematic Review

CONTEXT

Children with medical comorbidities are at greater risk for severe influenza and poorer clinical outcomes. Despite recommendations and funding, influenza vaccine coverage remains inadequate in these children.

OBJECTIVE

We aimed to systematically review literature assessing interventions targeting influenza vaccine coverage in children with comorbidities and assess the impact on influenza vaccine coverage.

DATA SOURCES

PubMed, Scopus, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Controlled Trials, Allied and Complementary Medicine Database, and Web of Science databases were searched.

STUDY SELECTION

Interventions targeting influenza vaccine coverage in children with medical comorbidities.

DATA EXTRACTION

Two reviewers independently screened articles, extracting studies' methods, interventions, settings, populations, and results. Four reviewers independently assessed risk of bias.

RESULTS

From 961 screened articles, 35 met inclusion criteria. Published studies revealed that influenza vaccine coverage was significantly improved through vaccination reminders and education directed at either patients' parents or providers, as well as by vaccination-related clinic process changes. Interventions improved influenza vaccine coverage by an average 60%, but no significant differences between intervention types were detected. Significant bias and study heterogeneity were also identified, limiting confidence in this effect estimate.

LIMITATIONS

A high risk of bias and overall low quality of evidence limited our capacity to assess intervention types and methods.

CONCLUSIONS

Interventions were shown to consistently improve influenza vaccine coverage; however, no significant differences in coverage between different intervention types were observed. Future well-designed studies evaluating the effectiveness of different intervention are required to inform future optimal interventions.

Assessing the Burden of Laboratory-Confirmed Respiratory Syncytial Virus Infection in a Population Cohort of Australian Children Through Record Linkage

BACKGROUND

Significant progress has been made towards an effective respiratory syncytial virus (RSV) vaccine. Age-stratified estimates of RSV burden are urgently needed for vaccine implementation. Current estimates are limited to small cohorts or clinical coding data only. We present estimates of laboratory-confirmed RSV across multiple severity levels.

METHODS

We linked laboratory, perinatal, and hospital data of 469 589 children born in Western Australia in 1996-2012. Respiratory syncytial virus tests and detections were classified into community, emergency department (ED), and hospital levels to estimate infection rates. Clinical diagnoses given to children with RSV infection presenting to ED or hospitalized were identified.

RESULTS

In 2000-2012, 10% (n = 45 699) of children were tested for RSV and 16% (n = 11 461) of these tested positive. Respiratory syncytial virus was detected in community, ED (both 0.3 per 1000 child-years), and hospital (2.4 per 1000 child-years) settings. Respiratory syncytial virus-confirmed rates were highest among children aged <3 months (31 per 1000 child-years). At least one third of children with RSV infection presenting to ED were diagnosed as other infection, other respiratory, or other (eg, agranulocytosis).

CONCLUSIONS

Respiratory syncytial virus is pervasive across multiple severity levels and diagnoses. Vaccines targeting children <3 months must be prioritized. Given that most children are never tested, estimating the under-ascertainment of RSV infection is imperative.

Epidemiology and seasonality of human parainfluenza serotypes 1-3 in Australian children

Background

Parainfluenza viruses are significant contributors to childhood respiratory illness worldwide, although detailed epidemiological studies are lacking. Few recent Australian studies have investigated serotype‐specific PIV epidemiology, and there is a paucity of southern hemisphere PIV reports. We report age‐stratified PIV hospitalisation rates and a mathematical model of PIV seasonality and dynamics in Western Australia (WA).

Methods

We used linked perinatal, hospital admission and laboratory diagnostic data of 469 589 children born in WA between 1996 and 2012. Age‐specific rates of viral testing and PIV detection in hospitalised children were determined using person time‐at‐risk analysis. PIV seasonality was modelled using a compartmental SEIRS model and complex demodulation methods.

Results

From 2000 to 2012, 9% (n = 43 627) of hospitalised children underwent PIV testing, of which 5% (n = 2218) were positive for PIV‐1, 2 or 3. The highest incidence was in children aged 1‐5 months (PIV‐1:62.6 per 100 000 child‐years, PIV‐2:26.3/100 000, PIV‐3:256/100 000), and hospitalisation rates were three times higher for Aboriginal children compared with non‐Aboriginal children overall (IRR: 2.93). PIV‐1 peaked in the autumn of even‐numbered years, and PIV‐3 annually in the spring, whereas PIV‐2 had inconsistent peak timing. Fitting models to the higher incidence serotypes estimated reproduction numbers of 1.24 (PIV‐1) and 1.72 (PIV‐3).

Conclusion

PIV‐1 and 3 are significant contributors towards infant respiratory hospitalisations. Interventions should prioritise children in the first 6 months of life, with respect to the observed autumn PIV‐1 and spring PIV‐3 activity peaks. Continued surveillance of all serotypes and investigation into PIV‐1 and 3 interventions should be prioritised.

Vaccine coverage in children born to migrant mothers in Australia: A population-based cohort study

BACKGROUND

Overall, infant immunisation coverage is currently >90% in Australia, but there are pockets of under-immunised children including children from migrant backgrounds. This study aimed to examine whether on-time vaccination coverage of diphtheria-tetanus-pertussis dose 3 (DTP3) for children born in Australia differed by mother's region of birth and if so, what factors were associated with these differences.

METHODS

We conducted a population-based cohort study using linked data on perinatal, immunisation and birth records for 2 million children born in Western Australia and New South Wales between 1996 and 2012. We assessed on-time coverage of DTP3 (vaccination from 2 weeks prior to, and up until 30 days after, the due date) in children with mothers born overseas. Logistic regression models were developed to determine factors associated with on-time coverage for each maternal region of birth and all regions combined, adjusting for a range of demographic factors. Adjusted estimates of coverage were calculated for the different regions of birth.

RESULTS

On-time DTP3 coverage was 76.2% in children of Australian born mothers, lower in children of mothers from Oceania (66.7%) and North America (68%), and higher in children born to mothers from South-East Asia (79.9%) and Southern Asia (79.3%). While most variables were consistently associated with lower coverage in all regions of birth, higher socioeconomic status and jurisdiction of birth showed varied results. Adjusted estimates of DTP3 coverage increased in children born to mothers from Australia (78.3%), Oceania (70.5%), Northern Africa (81.5%) and the Middle East (79.6%). DTP3 coverage decreased in children born to mothers from Europe and former USSR (74.6%), North-east Asia (75.2%), Southern Asia (76.7%), North America (65.5) and South/Central America and the Caribbean (73.2%).

CONCLUSIONS

On-time vaccination rates differed by mother's region of birth. More research is needed to determine the main reasons for these remaining differences to improve vaccine uptake and also help guide policy and practice.

Impact of Rotavirus Vaccines on Gastroenteritis Hospitalizations in Western Australia: A Time-series Analysis

Background

Rotavirus vaccination was introduced into the Australian National Immunisation Program in mid-2007. We aimed to assess the impact of the rotavirus vaccination program on the burden of hospitalizations associated with all-cause acute gastroenteritis (including rotavirus gastroenteritis and non-rotavirus gastroenteritis) in the Aboriginal and non-Aboriginal population in Western Australia.

Methods

We identified all hospital records, between July 2004 and June 2012, with a discharge diagnosis code for all-cause gastroenteritis. Age-specific hospitalization rates for rotavirus and non-rotavirus acute gastroenteritis before and after the introduction of the rotavirus vaccination program were compared. Interrupted time-series models were used to examine differences in the annual trends of all-cause gastroenteritis hospitalization between the two periods.

Results

Between July 2004 and June 2012, there were a total of 106,974 all-cause gastroenteritis-coded hospitalizations (1,381 rotavirus-coded [15% among Aboriginal] and 105,593 non-rotavirus gastroenteritis-coded [7% among Aboriginal]). Following rotavirus vaccination introduction, significant reductions in rotavirus-coded hospitalization rates were observed in all children aged <5 years (up to 79% among non-Aboriginal and up to 66% among Aboriginal). Among adults aged ≥65 years, rotavirus-coded hospitalizations were 89% (95% confidence interval, 16–187%) higher in the rotavirus vaccination program period. The time-series analysis suggested reductions in all-cause gastroenteritis hospitalizations in the post-vaccination period among both vaccinated and unvaccinated (age-ineligible) children, with increases observed in adults aged ≥45 years.

Conclusions

Rotavirus vaccination has been associated with a significant decline in gastroenteritis hospitalizations among children. The increase in the elderly requires further evaluation, including assessment of the cost-benefits of rotavirus vaccination in this population.

RSV prophylaxis use in high-risk infants in Western Australia, 2002-2013: a record linkage cohort study

Background

The monoclonal antibody, palivizumab is licensed for use in high-risk infants to prevent severe illness caused by respiratory syncytial virus (RSV). The level of its use and compliance with current jurisdictional guidelines which were amended in 2010, is unknown. We determined the level of palivizumab use in a cohort of high-risk infants in Western Australia.

Methods

Using probabilistically linked administrative data, we conducted a birth cohort study within tertiary neonatal intensive care units (NICUs) born between 2002 and 2013. We described palivizumab use by patient characteristics, eligibility criteria according to guidelines over the period of study and identified predictors of its use.

Results

Of 24,329 infants admitted to tertiary NICUs, 271 (1.1%) were dispensed 744 palivizumab doses with 62.5% being dispensed to infants born 2010–2013. The median number of doses received was 2. A total of 2679 infants met at least one of three criteria for palivizumab (criteria 1: gestational age at birth < 28 weeks and chronic lung disease; criteria 2: gestational age < 28 weeks and Aboriginal; criteria 3: congenital heart disease not otherwise in criteria 1 or 2). The extent of palivizumab use differed across the 3 groups. Of 803 infants meeting criteria 1, 21.8% received at least 1 dose of palivizumab; 52.8% from 2010 onwards. From 174 infants meeting criteria 2, 14.4% received at least 1 dose; 43.1% from 2010 onwards and from 1804 births meeting criteria 3, only 3.7% received at least 1 dose; 5.4% from year of birth 2010 onwards). In adjusted analyses, being born after 2010, being extreme preterm, chronic lung disease, congenital lung disease and being born in autumn or winter were independent predictors of palivizumab use.

Conclusion

In this high-risk setting and notwithstanding the limitations of our data sources, the level of compliance of palivizumab use against current guidelines was low. Most doses were dispensed to infants meeting at least one high-risk criterion. Evidence of incomplete dosing is an important finding in light of recent developments of single dose monoclonal antibodies offering longer protection.

Association between rotavirus vaccination and intussusception in Australian children: A record linkage study

BACKGROUND

Post-licensure surveillance studies have shown a small but increased risk of intussusception among infants in the days following rotavirus vaccination (RV).

OBJECTIVES

We assessed the temporal trends of intussusception-coded hospitalisations before and after the commencement of a universal rotavirus vaccination programme in Western Australia (WA) in 2007. We also assessed the perinatal factors and pathogens associated with these hospitalisations.

METHODS

Intussusception-coded hospitalisations occurring in a cohort of 367 476 WA-born children (2000-2012) aged <5 years were probabilistically linked to perinatal and pathology records. Age-specific incidence rates for overall and pathogen-specific intussusception-coded hospitalisations were calculated before (2000-2006) and after (2008-2012) RV introduction. Adjusted Cox proportional hazards models were used to assess perinatal risk factors for intussusception.

RESULTS

The overall rate of intussusception-coded hospitalisation was 26.4 per 100 000 child-years (95% confidence interval [CI] 24.0, 29.0) among children aged <5 years, with rates being 70% higher (95% CI 39, 107) in the RV period than in the pre-RV period. Compared with the pre-RV period, rates were higher among those aged 12-23 months (by 55%, 95% CI 5, 127) and 2-4 years (by 84%, 95% CI 20, 182) in the RV period. However, the risk of intussusception-coded hospitalisations associated with intussusception management-related procedure code(s) was similar among all age groups in both birth periods. Among infants aged <12 months, male sex, non-Aboriginal status, birth to multiparous mothers, and birth in RV era were independent risk factors associated with intussusception-coded hospitalisations. Adenovirus was strongly associated with intussusception (6.7 per 100 000 child-years, 95% CI 5.3, 9.3).

CONCLUSIONS

The risk of intussusception-coded hospitalisations was higher post-RV introduction, but not for intussusception-coded hospitalisations associated with procedure code(s). The increase was no higher in the vaccine-eligible age group than in older age groups, suggesting that the apparent increase is likely to be attributable to causes other than vaccination.

Early Childhood Health Outcomes Following In Utero Exposure to Influenza Vaccines: A Systematic Review

CONTEXT

Vaccination during pregnancy is an effective strategy for preventing infant disease; however, little is known about early childhood health after maternal vaccination.

OBJECTIVES

To systematically review the literature on early childhood health associated with exposure to influenza vaccines in utero.

DATA SOURCES

We searched CINAHL Plus, Embase, Medline, Scopus, and Web of Science for relevant articles published from inception to July 24, 2019.

STUDY SELECTION

We included studies published in English reporting original data with measurement of in utero exposure to influenza vaccines and health outcomes among children <5 years of age.

DATA EXTRACTION

Two authors independently assessed eligibility and extracted data on study design, setting, population, vaccines, outcomes, and results.

RESULTS

The search yielded 3647 records, of which 9 studies met the inclusion criteria. Studies examined infectious, atopic, autoimmune, and neurodevelopmental outcomes, and all-cause morbidity and mortality. Authors of 2 studies reported an inverse association between pandemic influenza vaccination and upper respiratory tract infections, gastrointestinal infections, and all-cause hospitalizations; and authors of 2 studies reported modest increased association between several childhood disorders and pandemic or seasonal influenza vaccination, which, after adjusting for confounding and multiple comparisons, were not statistically significant.

LIMITATIONS

Given the small number of studies addressing similarly defined outcomes, meta-analyses were deemed not possible.

CONCLUSIONS

Results from the few studies in which researchers have examined outcomes in children older than 6 months of age did not identify an association between exposure to influenza vaccines in utero and adverse childhood health outcomes.

Spatial patterns of tuberculosis and HIV co-infection in Ethiopia

Background

Tuberculosis (TB) and human immunodeficiency virus (HIV) are the leading causes of infectious-disease-related deaths in Ethiopia, but little is known about their spatial distribution across the country. The aim of this study was to investigate the spatial patterns of TB and HIV co-infection in Ethiopia at the district level.

Methods

We conducted an ecological study using TB and HIV data reported from all regions of Ethiopia through the national Health Management Information System (HMIS), between June 2015 and June 2017. Spatial clustering was assessed using Moran’s I statistic and Getis-Ord statistic. Spatial binomial regression models were constructed separately for the prevalence of TB among people living with HIV and for the prevalence of HIV among TB patients, with and without spatial components using a Bayesian approach.

Results

A total of 1,830,880 HIV and 192,359 TB patients were included in the analysis. The prevalence of HIV among TB patients was 7.34%; hotspots were observed in districts located in Amhara, Afar, and Gambela regions, and cold spots were observed in Oromiya and Southern Nations, Nationalities, and People (SNNP) regions. The prevalence of TB among people living with HIV varied from 0.7% in Oromia region to 14.5% in Afar region. Hotspots of TB prevalence among people living with HIV were observed in districts located in Gambela, Afar, Somali, and Oromiya regions; whereas the cold spots were observed in districts located in Amhara and Tigray regions. The ecological-level factors associated with the prevalence of TB among people living with HIV were low wealth index (OR: 1.49; 95% CrI: 1.05, 2.05), low adult literacy rate (OR: 0.67; 95% CrI: 0.46, 0.94), and distance to an international border (OR: 0.61; 95% CrI: 0.40, 0.91). The factors associated with the prevalence of HIV among TB patients were poor health care access (OR: 0.76; 95% CrI: 0.59, 0.95), low wealth index (OR: 1.31; 95% CrI: 1.01, 1.67), and low adult literacy rate (OR: 1.37; 95% CrI: 1.03, 1.78).

Conclusion

Our study provides evidence for geographic clustering of TB/HIV co-infection in Ethiopia. Health care access, proximity to international borders, and demographic factors such as low wealth index and adult literacy were significantly associated with the prevalence of TB/HIV co-infection.

Effectiveness of Palivizumab against Respiratory Syncytial Virus: Cohort and Case Series Analysis

OBJECTIVE

To measure the real-world effectiveness of palivizumab immunoprophylaxis against respiratory syncytial virus (RSV)-confirmed infection before age 2 years in a population-cohort of high-risk infants.

STUDY DESIGN

Palivizumab is funded for high-risk infants in Western Australia. We used probabilistically linked administrative data encompassing RSV laboratory-confirmed infections, hospital admissions, and palivizumab dispensing records for a cohort of 24 329 high-risk infants admitted to neonatal intensive care units, born 2002-2013 with follow-up to 2015. We used a traditional cohort method with Cox proportional hazards regression and a self-controlled case series analysis to assess effectiveness of palivizumab in reducing RSV-confirmed infection by number of doses.

RESULTS

From the cohort of 24 329 infants, 271 (1.1%) received at least 1 dose of palivizumab and 1506 (6.2%) had at least 1 RSV-confirmed infection before age 2 years. Using the traditional cohort approach, we found no protective association of palivizumab receipt with RSV detection (adjusted hazard ratio = 0.99 [95% CI 0.5, 1.9] for 1 dose). However, using a self-controlled case series to eliminate confounding by indication, a protective association was seen with a 74% lower RSV incidence (relative incidence = 0.26; 95% CI 0.11, 0.67) following any dose of palivizumab compared with control (nonexposed) periods.

CONCLUSIONS

After accounting for confounding by indication through a self-controlled analysis, palivizumab appeared effective for reducing virologically confirmed RSV in this high-risk cohort.

The Impact of Pneumococcal Vaccination on Bacterial and Viral Pneumonia in Western Australian Children: Record Linkage Cohort Study of 469589 Births, 1996-2012

Background

Pneumococcal conjugate vaccine (PCV) was included in Australia's National Immunisation Program for all children from 2005. We assessed the impact of PCV on all-cause and pathogen-specific pneumonia hospitalizations in Western Australian (WA) children aged ≤16 years.

Methods

All hospitalizations with pneumonia-related International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification diagnosis codes occurring in WA-born children (1996-2012) were linked to pathology records. Age-specific incidence rate ratios and temporal trends for all-cause and pathogen-specific pneumonia hospitalizations were calculated before and after PCV introduction.

Results

Among 469589 births, there were 15175 pneumonia-related hospitalizations. Hospitalization rates were 6.7 (95% confidence interval, 6.4-6.9) times higher in Aboriginal than in non-Aboriginal children. Following PCV introduction, all-cause pneumonia hospitalizations showed significant declines across all age groups. A pathogen was identified in 2785 of 6693 (41.6%) pneumonia hospitalizations that linked to a pathology record. Respiratory syncytial virus (RSV) was most frequently identified, with RSV-associated pneumonia hospitalization rates of 89.6/100000 child-years in Aboriginal and 26.6/100000 child-years in non-Aboriginal children. The most common bacterial pathogen was Streptococcus pneumoniae in Aboriginal children (32.9/100000 child-years) and Mycoplasma pneumoniae in non-Aboriginal children (8.4/100000 child-years). Viral pneumonia rates declined in all children following PCV introduction, with the greatest declines seen in non-Aboriginal children; declines in bacterial pneumonia were observed in non-Aboriginal children.

Conclusions

Based on our ecological analyses, PCV seems to have had an impact on hospitalizations for pneumonia, suggesting that the pneumococcus is likely to play a role in both bacterial and viral pneumonia. Respiratory viruses remain an important pathogen in childhood pneumonia. Vaccines targeting respiratory viruses are needed to combat the residual burden of childhood pneumonia.

2761. Interventions to Improve Influenza Vaccination Coverage in Children with Medical Comorbidities: A Meta-Analysis

Background

Influenza vaccination is the most effective influenza prevention tool for children with medical comorbidities. Despite this, coverage remains inadequate. Numerous interventions to improve vaccination coverage have been assessed, yet there remains a paucity of data comparing the relative efficacy and effectiveness of different interventions.

Methods

We searched MEDLINE, PubMed, Scopus, Embase, CINAHL, CENTRAL, and Web of Science (1980 to March 2019) for studies evaluating interventions which sought to improve influenza vaccine coverage in children with medical comorbidities. Interventions were divided into those targeting parents, targeting vaccination providers, and targeting the hospital, clinic or ward. Screening and data extraction from publications meeting inclusion criteria was performed by two reviewers. Results were pooled and meta-analyses were performed using Mantel–Haenszel random-effects models in Review Manager 5.

Results

35 articles met inclusion criteria; 14 cross-sectional, 12 randomized trials, and 9 cohort studies, 25 articles had sufficient data for pooled analysis. Of the included interventions, 17 were based within primary care or community-based settings, 17 were based in hospitals or tertiary clinics, and 1 intervention was conducted across both primary and tertiary settings. Interventions overall increased influenza vaccination likelihood by 33% (RR = 1.33: 95% CI 1.31, 1.35). Interventions targeting providers’ influenza vaccine knowledge increased vaccine coverage (RR = 1.42: 95% CI 1.36, 1.49) greater than those targeting parental knowledge (RR = 1.23: 95% CI 1.21, 1.26). Conversely, vaccination reminders targeting parents increased vaccine coverage (RR = 1.53: 95% CI 1.49, 1.58) greater than reminders targeting providers (RR = 1.23: 95% CI 1.20, 1.27). Interventions targeting hospitals, clinics or ward processes had the weakest impact on coverage (RR = 1.15: 95% CI 1.13, 1.17).

Conclusion

Interventions targeting parents, providers, and places individually have all shown to improve influenza vaccination in children with medical comorbidities. However, specifically targeting providers’ vaccine knowledge and parental reminders appear to have the greatest impact on vaccine uptake.

Disclosures

All authors: No reported disclosures.

454. Perinatal Risk Factors Associated with Skin Infection Hospitalisation in Western Australian Aboriginal and Non-Aboriginal Children

Background

Hospitalisation with skin infection in Western Australian (WA) Aboriginal children is common, with the highest rates in infants and children from remote WA. We aimed to quantify infant, maternal, and sociodemographic risk factors for skin infection hospitalization in WA children, focusing on Aboriginal children aged <17 years.

Methods

We conducted a retrospective population-based cohort study with linked perinatal and hospitalization data on WA-born children (1996–2012), of whom 31,348 (6.7%) were Aboriginal. We used Cox regression to calculate adjusted hazard ratios and associated population attributable fractions (PAFs) for perinatal factors attributed to the first hospitalization with skin infection. To identify specific risk factors for early-onset infection, we further restricted the cohort to infants aged <1 year.

Results

Overall, 5,439 (17.4%) Aboriginal and 6,750 (1.5%) non-Aboriginal children were hospitalized at least once with a skin infection. Aboriginal infants aged <1 year had the highest skin infection hospitalization rate (63.2/1,000 child-years). The strongest risk factors in Aboriginal children aged <17 years were socio-economic disadvantage, very remote location at birth and multi-parity (≥3 previous pregnancies) accounting for 24%, 23% and 15% of skin infection hospitalizations, respectively. Other risk factors included maternal age <20 years, maternal smoking during pregnancy and low birthweight.

Conclusion

We have quantified the relative influence of perinatal risk factors associated with skin infection hospitalizations in WA children, providing measures indicating which factors have the potential to reduce the most hospitalizations. Our evidence supports existing calls for substantial government investment in addressing underlying social and environmental barriers to healthy skin in WA Aboriginal children but also identifies potential areas to target health promotion messaging at individuals/families on maternal smoking during pregnancy and skin hygiene for families.

Disclosures

All authors: No reported disclosures.

Infant, maternal and demographic predictors of delayed vaccination: A population-based cohort study

BACKGROUND

Receiving vaccines at or close to their due date (vaccination timeliness) is a now key measure of program performance. However, studies comprehensively examining predictors of delayed infant vaccination are lacking. We aimed to identify predictors of short and longer-term delays in diphtheria-tetanus-pertussis (DTP) vaccination by dose number and ethnicity.

METHODS

Perinatal, notification, death and immunisation databases were linked for 1.3 million births in 2000-11 from two Australian states (Western Australia and New South Wales), with follow-up data until 2013. Ordinal logistic regression was used to estimate adjusted relative risks (RR) by degree of delay. Separate models were constructed for each vaccine dose and for Aboriginal and non-Aboriginal children.

RESULTS

Each dose-specific cohort included at least 49,000 Aboriginal and 1.1 million non-Aboriginal children. Delayed receipt was more common among Aboriginal than non-Aboriginal children (eg for the first dose of DTP [DTP1] 19.4 v 8.1%). Risk factors for delayed vaccination were strongest for DTP1, and delayed receipt of DTP1 was a key driver of subsequent delays; every week DTP1 was delayed was associated with a 1.6 to 2-fold increased risk of delayed DTP2 receipt. For DTP1, ≥3 previous pregnancies (the only factor more strongly associated with longer than shorter delays; RR ≥5 compared to no previous pregnancies), and children born to mothers <20 years of age (RR ≥2 compared to ≥35 years) were at highest risk of delay. Other independent predictors were prematurity, maternal smoking during pregnancy, and being born in Western Australia (if Aboriginal) or another country in the Oceania region.

CONCLUSION

The sub-populations at risk for delayed vaccination we have identified are likely generalisable to other high-income settings. Measures to improve their dose 1 timeliness, particularly for children with older siblings, are likely to have significant flow-on benefits for timeliness of later doses.

Perinatal risk factors associated with skin infection hospitalisation in Western Australian Aboriginal and Non-Aboriginal children

BACKGROUND

Hospitalisation with skin infection in Western Australian (WA) Aboriginal children is common, with the highest rates in infants and children from remote WA.

OBJECTIVE

We aimed to quantify infant, maternal, and sociodemographic risk factors for skin infection hospitalisation in WA children, focussing on Aboriginal children aged <17 years.

METHODS

We conducted a retrospective population-based cohort study with linked perinatal and hospitalisation data on WA-born children (1996-2012), of whom 31 348 (6.7%) were Aboriginal. We used Cox regression to calculate adjusted hazard ratios and associated population attributable fractions (PAFs) for perinatal factors attributed to first hospitalisation with skin infection. To identify specific risk factors for early-onset infection, we further restricted the cohort to infants aged <1 year.

RESULTS

Overall, 5439 (17.4%) Aboriginal and 6750 (1.5%) non-Aboriginal children were hospitalised at least once with a skin infection. Aboriginal infants aged <1 year had the highest skin infection hospitalisation rate (63.2 per 1000 child-years). The strongest risk factors in Aboriginal children aged <17 years were socio-economic disadvantage, very remote location at birth, and multi-parity (≥3 previous pregnancies) accounting for 24%, 23%, and 15% of skin infection hospitalisations, respectively. Other risk factors included maternal age <20 years, maternal smoking during pregnancy, and low birthweight.

CONCLUSIONS

We have quantified the relative influence of perinatal risk factors associated with skin infection hospitalisations in WA children, providing measures indicating which factors have the potential to reduce the most hospitalisations. Our evidence not only supports existing calls for substantial government investment in addressing underlying social and environmental barriers to healthy skin in WA Aboriginal children but also identifies potential areas to target health promotion messaging at individuals/families on maternal smoking during pregnancy and skin hygiene for families.

Timeliness and factors associated with rotavirus vaccine uptake among Australian Aboriginal and non-Aboriginal children: A record linkage cohort study

OBJECTIVES

Rotavirus vaccines (RV), included in Australia's National Immunisation Program from mid-July 2007, are unique in strict time limits for administration. Here, we report on timeliness of RV uptake, compare cumulative RV coverage to age 12 months with DTPa, and assess factors associated with receipt of RV among Aboriginal and non-Aboriginal children.

METHODS

Birth records for 681,456 children born in two Australian states in 2007-2012 were probabilistically linked to national immunisation records. We assessed on-time coverage (defined as receipt of vaccine dose between 4 days prior to scheduled date and the recommended upper limit) for RV and compared this to diphtheria-tetanus-pertussis (DTPa) vaccine. Logistic regression modelling was used to assess independent determinants of receipt of RV.

RESULTS

Compared to non-Aboriginal infants, on-time RV coverage was lower for all doses among Aboriginal infants. Post the upper age limit of RV dose2, DTPa dose2 coverage increased by 9-16% to ≥90%, whereas RV coverage remained around 77% (Aboriginal) and 85% (non-Aboriginal). Compared to first-born children, the adjusted odds of receiving ≥1 RV dose if born to a mother with ≥3 previous births was 0.30 (95%CI: 0.27-0.34) among Aboriginal, and 0.53 (95%CI: 0.51-0.55) among non-Aboriginal children. Prematurity (<33 weeks), low birthweight (<1500 g), maternal age <20 years, maternal smoking during pregnancy and living in a disadvantaged area were independently associated with decreased vaccine uptake.

CONCLUSIONS

Aboriginal children are at greater risk of rotavirus disease than non-Aboriginal children and delayed vaccine receipt is substantially higher. Although specific programs targeting groups at risk of delayed vaccination might improve RV coverage, relaxation of upper age restrictions is most readily implementable, and its overall risk-benefit should be evaluated.

Effectiveness of pneumococcal conjugate vaccine against hospital admissions for pneumonia in Australian children: a retrospective, population-based, record-linked cohort study

BACKGROUND

Reductions in pneumonia hospitalisations following introduction of pneumococcal conjugate vaccines (PCVs) have been reported from high-incidence and low-incidence settings but long-term data comparing vaccinated with unvaccinated children are sparse.

METHODS

We did a retrospective, population-based, record-linkage cohort study in Australian children using administrative health data from the Western Australian Midwives' Notification System and New South Wales Perinatal Data Collection, and the birth and death registries in both states. PCV vaccination details, pneumonia-coded hospital admissions, and invasive pneumococcal disease notification records were individually linked for children born between 2001 and 2012. The primary outcome was defined as the first hospital admission for all-cause pneumonia. Cox models were used to calculate adjusted hazard ratios (HR) to estimate the effect of PCV doses on pneumonia-coded hospital admissions by Aboriginal status, birth period, remoteness, and pneumonia diagnostic category in children younger than 2 years. Person-time of follow-up time for each child started at birth and was censored at the earliest of first hospital admission for all-cause pneumonia, death, invalid PCV dose, when the child reached age 24 months, or the end date of the study period (Dec 31, 2013) FINDINGS: The study cohort comprised 1 365 893 children liveborn between Jan 1, 2001, and Dec 31, 2012, of whom 66 484 (4·9%) were identified as Aboriginal. The overall rate for all-cause pneumonia hospital admissions for children younger than 2 years over the entire study period was 17·6/1000 child-years in Aboriginal children and 5·5/1000 child-years in non-Aboriginal children. Compared with children born between 2001 and 2004 (ie, the pre-universal PCV period), the incidence of pneumonia-coded hospital admissions decreased in both vaccinated (6·5 vs 5·7 per 1000 child-years [12% reduction, 95% CI 3-21; p=0·01]) and unvaccinated non-Aboriginal children (6·8 vs 3·7 [45% reduction; 41-49]) born 2005-12 (the universal PCV period); among Aboriginal children, declines were significant only among those vaccinated (27·4 vs 14·1 [49% reduction, 40-55]). Among Aboriginal children born 2005-12, the risk of pneumonia-coded hospital admission after three doses of PCV was lower than those unvaccinated (adjusted HR 0·83, 95% CI 0·65-0·99) but, among non-Aboriginal children, the risk was similar (adjusted HR 1·09, 0·98-1·22). Overall, remote-born Aboriginal children had the highest incidence of hospital admission for pneumonia and among children born 2005-12, the adjusted risk was 37% lower (adjusted HR 0·63, 95% CI 0·42-0·96) among those fully vaccinated than those unvaccinated.

INTERPRETATION

Reductions in pneumonia-coded hospital admissions in unvaccinated children predominated in non-Aboriginal children with low incidence of pneumonia but were not significant in Aboriginal children with high incidence. These findings have potential implications for measuring PCV effect using a non-specific endpoint such as all-cause pneumonia in high-incidence populations.

FUNDING

Commonwealth Government Collaborative Research Infrastructure Strategy and Education Investment Fund Super Science Initiative and the Australian National Health and Medical Research Council.

Temporal trends and socioeconomic differences in acute respiratory infection hospitalisations in children: an intercountry comparison of birth cohort studies in Western Australia, England and Scotland

OBJECTIVES

Acute respiratory infections (ARIs) are a global cause of childhood morbidity. We compared temporal trends and socioeconomic disparities for ARI hospitalisations in young children across Western Australia, England and Scotland.

DESIGN

Retrospective population-based cohort studies using linked birth, death and hospitalisation data.

SETTING AND PARTICIPANTS

Population birth cohorts spanning 2000-2012 (Western Australia and Scotland) and 2003-2012 (England).

OUTCOME MEASURES

ARI hospitalisations in infants (<12 months) and children (1-4 years) were identified through International Classification of Diseases, 10th edition diagnosis codes. We calculated admission rates per 1000 child-years by diagnosis and jurisdiction-specific socioeconomic deprivation and used negative binomial regression to assess temporal trends.

RESULTS

The overall infant ARI admission rate was 44.3/1000 child-years in Western Australia, 40.7/1000 in Scotland and 40.1/1000 in England. Equivalent rates in children aged 1-4 years were 9.0, 7.6 and 7.6. Bronchiolitis was the most common diagnosis. Compared with the least socioeconomically deprived, those most deprived had higher ARI hospitalisation risk (incidence rate ratio 3.9 (95% CI 3.5 to 4.2) for Western Australia; 1.9 (1.7 to 2.1) for England; 1.3 (1.1 to 1.4) for Scotland. ARI admissions in infants were stable in Western Australia but increased annually in England (5%) and Scotland (3%) after adjusting for non-ARI admissions, sex and deprivation.

CONCLUSIONS

Admissions for ARI were higher in Western Australia and displayed greater socioeconomic disparities than England and Scotland, where ARI rates are increasing. Prevention programmes focusing on disadvantaged populations in all three countries are likely to translate into real improvements in the burden of ARI in children.

Australian Aboriginal children have higher hospitalization rates for otitis media but lower surgical procedures than non-Aboriginal children: A record linkage population-based cohort study

Introduction

Otitis media (OM) is one of the most common infectious diseases affecting children globally and the most common reason for antibiotic prescription and paediatric surgery. Australian Aboriginal children have higher rates of OM than non-Aboriginal children; however, there are no data comparing OM hospitalization rates between them at the population level. We report temporal trends for OM hospitalizations and in-hospital tympanostomy tube insertion (TTI) in a cohort of 469,589 Western Australian children born between 1996 and 2012.

Materials and methods

We used the International Classification of Diseases codes version 10 to identify hospitalizations for OM or TTI recorded as a surgical procedure. Using age-specific population denominators, we calculated hospitalization rates per 1,000 child-years by age, year and level of socio-economic deprivation.

Results

There were 534,674 hospitalizations among 221,588 children hospitalized at least once before age 15 years. Aboriginal children had higher hospitalization rates for OM than non-Aboriginal children (23.3/1,000 [95% Confidence Interval (CI) 22.8,24.0] vs 2.4/1,000 [95% CI 2.3,2.4] child-years) with no change in disparity over time. Conversely non-Aboriginal children had higher rates of TTI than Aboriginal children (13.5 [95% CI 13.2,13.8] vs 10.1 [95% CI 8.9,11.4]). Children from lower socio-economic backgrounds had higher OM hospitalization rates than those from higher socio-economic backgrounds, although for Aboriginal children hospitalization rates were not statistically different across all levels of socio-economic disadvantage. Hospitalizations for TTI among non-Aboriginal children were more common among those from higher socio-economic backgrounds. This was also true for Aboriginal children; however, the difference was not statistically significant. There was a decline in OM hospitalization rates between 1998 and 2005 and remained stable thereafter.

Conclusion

Aboriginal children and children from lower socio-economic backgrounds were over-represented with OM-related hospitalizations but had fewer TTIs. Despite a decrease in OM and TTI hospitalization rates during the first half of the study for all groups, the disparity between Aboriginal and non-Aboriginal children and between those of differing socioeconomic deprivation remained.

Caregiver's attitudes, beliefs, and experiences for influenza vaccination in Australian children with medical comorbidities

BACKGROUND

Influenza vaccination is recommended and funded for Australian children with medical comorbidities that increase their risk of severe influenza. Despite this, influenza vaccine coverage remains low within this population. We examined caregivers' attitudes and practices for influenza vaccination in children with medical comorbidities.

METHODS

Cross-sectional surveys were conducted with caregivers of children (6 months to <18 years old) with medical comorbidities attending sub-speciality paediatric outpatient clinics at the Royal Children's Hospital (Melbourne), Princess Margaret Hospital (Perth), and Leading Steps private paediatric clinic (Gold Coast). Multivariate linear regression was used to identify surveys responses predictive of receipt of influenza vaccination in 2017.

RESULTS

From the 611 surveys collected, 556 were suitable for analysis. Caregiver reported 2017 influenza vaccine coverage was 52.2% in children with medical comorbidities. Caregivers who believed influenza vaccines to be ≥50% effective were more likely to vaccinate their children (adjusted Odds Ratio [aOR]:3.79 (2.41; 5.96). Those who expressed concerns about vaccine side effects were less likely to vaccinate their children (aOR: 0.49 [95% CI: 0.30; 0.80]). Influenza vaccine uptake was significantly more likely for children who had been previously recommended influenza vaccination by their hospital-based physician (aOR: 4.33 [95% CI: 2.58; 7.27]) and had previously received a hospital-based vaccination (aOR: 3.11 [95% CI 1.79; 5.40]). Hospital-based physicians were also caregivers' most commonly reported source of trusted vaccination information (63.5%). Whilst only 29.3% of caregivers reported their child had been recommended influenza vaccination during a previous admission, 80.1% of caregivers stated they were receptive to their child receiving potential future influenza vaccinations during hospitalisations.

CONCLUSIONS

Reported influenza vaccination coverage in children with medical comorbidities remains inadequate. An important finding of this study is that influenza vaccination recommendation by children's hospital physicians and previous vaccine receipt in hospital was associated with vaccine uptake. Opportunities for vaccination, especially during hospitalisation, must be examined.

Geographical disparities in emergency department presentations for acute respiratory infections and risk factors for presenting: a population-based cohort study of Western Australian children

INTRODUCTION

Studies examining acute respiratory infections (ARIs) in emergency department (EDs), particularly in rural and remote areas, are rare. This study aimed to examine the burden of ARIs among Aboriginal and non-Aboriginal children presenting to Western Australian (WA) EDs from 2002 to 2012.

METHOD

Using a retrospective population-based cohort study linking ED records to birth and perinatal records, we examined presentation rates for metropolitan, rural and remote Aboriginal and non-Aboriginal children from 469 589 births. We used ED diagnosis information to categorise presentations into ARI groups and calculated age-specific rates. Negative binomial regression was used to investigate association between risk factors and frequency of ARI presentation.

RESULTS

Overall, 26% of presentations were for ARIs. For Aboriginal children, the highest rates were for those aged <12 months in the Great Southern (1233 per 1000 child-years) and Pilbara regions (1088 per 1000 child-years). Rates for non-Aboriginal children were highest in children <12 months in the Southwest and Kimberley (400 and 375 per 1000 child-years, respectively). Presentation rates for ARI in children from rural and remote WA significantly increased over time in all age groups <5 years. Risk factors for children presenting to ED with ARI were: male, prematurity, caesarean delivery and residence in the Kimberley region and lower socio-economic areas.

CONCLUSION

One in four ED presentations in WA children are for ARIs, representing a significant out-of-hospital burden with some evidence of geographical disparity. Planned linkages with hospital discharge and laboratory detection data will aid in assessing the sensitivity and specificity of ARI diagnoses in ED.

Optimising the use of linked administrative data for infectious diseases research in Australia

Infectious diseases remain a major cause of morbidity in Australia. A wealth of data exists in administrative datasets, which are linked through established data-linkage infrastructure in most Australian states and territories. These linkages can support robust studies to investigate the burden of disease, the relative contribution of various aetiological agents to disease, and the effectiveness of population-based prevention policies - research that is critical to the success of current and future vaccination programs. At a recent symposium in Perth, epidemiologists, clinicians and policy makers in the infectious diseases field discussed the various benefits of, and barriers to, data-linkage research, with a focus on respiratory infection research. A number of issues and recommendations emerged. The demand for data-linkage projects is starting to outweigh the capabilities of exisiting data-linkage infrastructure. There is a need to further streamline processes relating to data access, increase data sharing and conduct nationally collaborative projects. Concerns about data security and sharing across jurisdictional borders can be addressed through multiple safe data solutions. Researchers need to do more to ensure that the benefits of linking datasets to answer policy-relevant questions are being realised for the benefit of community groups, government authorities, funding bodies and policy makers. Increased collaboration and engagement across all sectors can optimise the use of linked data to help reduce the burden of infectious diseases.

Assessment of on-time vaccination coverage in population subgroups: A record linkage cohort study

Reported infant vaccination coverage at age 12 months in Australia is >90%. On-time coverage of the 2-4-6 month schedule and coverage in specific populations is rarely reported. We conducted a population-based cohort study of 1.9 million Australian births, 1996-2012, combining individual birth and perinatal records with immunisation records through probabilistic linkage. We assessed on-time coverage across 13 demographic and perinatal characteristics of diphtheria-tetanus-pertussis vaccines (DTP) defined as vaccination 14 days prior to the scheduled due date, to 30 days afterwards. On-time DTP vaccination coverage in non-Aboriginal infants was 88.1% for the 2-month dose, 82.0% for 4-month dose, and 76.7% for 6-month dose; 3-dose coverage was 91.3% when assessed at 12 months. On-time DTP coverage for Aboriginal infants was 77.0%, 66.5%, and 61.0% for the 2-4-6 month dose; 3-dose coverage at 12 months was 79.3%. Appreciable differences in on-time coverage were observed across population subgroups. On-time coverage in non-Aboriginal infants born to mothers with ≥3 previous pregnancies was 62.5% for the 6-month dose (47.9% for Aboriginal infants); up to 23.5 percentage points lower than for first-borns. Infants born to mothers who smoked during pregnancy had coverage 8.7-10.3 percentage points lower than infants born to non-smoking mothers for the 4- and 6-month dose. A linear relationship was apparent between increasing socio-economic disadvantage and decreasing on-time coverage. On-time coverage of the 2-4-6 month schedule is only 50-60% across specific population subgroups representing a significant avoidable public health risk. Aboriginal infants, multiparous mothers, and those who are socio-economically disadvantaged are key groups most likely to benefit from targeted programs addressing vaccine timeliness.

Effectiveness of a 3 + 0 pneumococcal conjugate vaccine schedule against invasive pneumococcal disease among a birth cohort of 1.4 million children in Australia

BACKGROUND

Most studies use indirect cohort or case-control methods to estimate vaccine effectiveness (VE) of 7- and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13) against invasive pneumococcal disease (IPD). Neither method can measure the benefit vaccination programs afford the unvaccinated and many studies were unable to estimate dose-specific VE. We linked Australia's national immunisation register with health data from two states to calculate IPD incidence by vaccination status and VE for a 3 + 0 PCV schedule (doses at 2, 4, 6 months, no booster) among a cohort of 1.4 million births.

METHODS

Births records for 2001-2012 were probabilistically linked to IPD notifications, hospitalisations, deaths, and vaccination history (available until December 2013). IPD rates in vaccinated and unvaccinated children <2 years old were compared using Cox proportional hazards models (adjusting for potential confounders), with VE = (1 - adjusted hazard ratio) × 100. Separate models were performed for all-cause, PCV7, PCV13 and PCV13-non-PCV7 serotype-specific IPD, and for Aboriginal and non-Aboriginal children.

RESULTS

Following introduction of universal PCV7 in 2005, rates of PCV7 serotype and all-cause IPD in unvaccinated children declined 89.5% and 61.4%, respectively, to be similar to rates in vaccinated children. Among non-Aboriginal children, VEs for 3 doses were 94.2% (95%CI: 81.9-98.1) for PCV7 serotype-specific IPD, 85.6% (95%CI: 60.5-94.8) for PCV13-non-PCV7 serotype-specific IPD and 80.1% (95%CI: 59.4-90.3) for all-cause IPD. There were no statistically significant differences between the VEs for 3 doses and for 1 or 2 doses against PCV13 and PCV13-non-PCV7 serotype-specific IPD, or between Aboriginal and non-Aboriginal children.

CONCLUSION

Our population-based cohort study demonstrates that >90% coverage in the first year of a universal 3 + 0 PCV program provided high population-level protection, predominantly attributable to strong herd effects. The size of the cohort enabled calculation of robust dose-specific VE estimates for important population sub-groups relevant to vaccination policies internationally.

Abstract P5-21-26: T-DM1 activity in metastatic HER2-positive breast cancer patients who have received prior trastuzumab and pertuzumab: NSABP B-005

Background :

The pivotal phase III EMILIA trial reported a progression free survival (PFS) rate of 9.6 months and an objective response rate of 43% with T-DM1 in patients with HER2-positive metastatic breast cancer previously treated with trastuzumab and a taxane. However, there is very limited data on the efficacy of T-DM1 in patients who have received prior pertuzumab either neoadjuvantly or as first line therapy in the metastatic setting. The primary goal of this study was to assess the clinical efficacy (tumor response rates and median duration on therapy) of T-DM1 in patients previously treated with pertuzumab and trastuzumab.

Methods:

After IRB approval, a cancer data registry and electronic pharmacy database were utilized to identify breast cancer patients receiving treatment with T-DM1 at Cleveland Clinic and University of Pittsburgh. Patients that received trastuzumab and pertuzumab, in either the neoadjuvant or metastatic setting, with baseline and follow up imaging available for review were identified. Patient charts were reviewed to collect accurate information about the treatment sequencing and outcomes. RECIST version 1.1 was utilized for tumor assessment and patients with measurable disease and non measurable disease were included in the study.

Results:

We identified a total of 23 patients with a median age of 55 years that met the inclusion criteria. 69% percent of patients received T-DM1 as first line or second line therapy and 31% received it as third line or later. All patients had at least 1 measurable lesion. Best overall response showed rates of complete response, partial response and stable disease of 17%, 26% and 22% respectively. 35% patients progressed on first assessment after start of treatment. The median duration on therapy was 5.3 months (range 3 weeks to 33 months) with 43% of patients receiving T-DM1 for greater than 6 months.

Conclusion:

Our results were comparable to those reported by EMILIA trial. T-DM1 has reasonable clinical efficacy in patients who have received prior treatment with pertuzumab and trastuzumab with an overall response rate of 43% and median duration on therapy of 5.3 months.

Citation Format: Tiwari SR, Sussman T, Kota K, Moore HC, Montero AJ, Budd GT, Puhalha S, Abraham J. T-DM1 activity in metastatic HER2-positive breast cancer patients who have received prior trastuzumab and pertuzumab: NSABP B-005 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-26.

Advances in Vaccines to Prevent Viral Respiratory Illnesses in Children

Childhood vaccination has played a critical role in the reduction of morbidity and mortality from communicable diseases, including specific respiratory pathogens. Acute lower respiratory infection (ALRI) of both bacterial and viral aetiology continues to impact global child health. Key bacterial pathogens including Streptococcus pneumoniae and Haemophilus influenza type b are specifically targeted with current vaccination programmes, while at present there are less effective strategies for the prevention of viral disease. Influenza vaccines, including both live attenuated intranasal vaccines and inactivated influenza vaccines, are limited by seasonal strain variation and unsustained immunity. Research into the development of a universal influenza vaccine is ongoing; potential targets are the conserved regions of the virus such as the M2e antigen and hemagglutinin stalk. Respiratory syncytial virus (RSV) and parainfluenza virus 3 (PIV3) are the viral pathogens most commonly causing ALRI in children, particularly the infant population. Currently, no vaccine exists for either virus. Over the last decade, promising advances have been made. Protection of neonates via maternal RSV immunisation is being assessed in a phase III clinical trial, with many other candidates for RSV and PIV3 at less advanced stages of development.

Record linkage study of the pathogen-specific burden of respiratory viruses in children

Background

Reliance on hospital discharge diagnosis codes alone will likely underestimate the burden of respiratory viruses.

Objectives

To describe the epidemiology of respiratory viruses more accurately, we used record linkage to examine data relating to all children hospitalized in Western Australia between 2000 and 2012.

Patients/Methods

We extracted hospital, infectious disease notification and laboratory data of a cohort of children born in Western Australia between 1996 and 2012. Laboratory records of respiratory specimens collected within 48 hours of admission were linked to hospitalization records. We calculated the frequency and rates of virus detection. To identify groups where under‐ascertainment for respiratory viruses was greatest, we used logistic regression to determine factors associated with failure to test.

Results and conclusions

Nine percentage of 484 992 admissions linked to a laboratory record for respiratory virus testing. While 62% (n = 26 893) of laboratory‐confirmed admissions received respiratory infection diagnosis codes, 38% (n = 16 734) had other diagnoses, notably viral infection of unspecified sites. Of those tested, incidence rates were highest for respiratory syncytial virus (247 per 100 000 child‐years) followed by parainfluenza (63 per 100 000 child‐years). Admissions among older children and those without a respiratory diagnosis were associated with failure to test for respiratory viruses. Linked data can significantly enhance diagnostic codes when estimating the true burden of disease. In contrast to current emphasis on influenza, respiratory syncytial virus and parainfluenza were the most common viral pathogens among hospitalized children. By characterizing those failing to be tested, we can begin to quantify the under‐ascertainment of respiratory viruses.

Potential impact of a maternal vaccine for RSV: A mathematical modelling study

Respiratory syncytial virus (RSV) is a major cause of respiratory morbidity and one of the main causes of hospitalisation in young children. While there is currently no licensed vaccine for RSV, a vaccine candidate for pregnant women is undergoing phase 3 trials. We developed a compartmental age-structured model for RSV transmission, validated using linked laboratory-confirmed RSV hospitalisation records for metropolitan Western Australia. We adapted the model to incorporate a maternal RSV vaccine, and estimated the expected reduction in RSV hospitalisations arising from such a program. The introduction of a vaccine was estimated to reduce RSV hospitalisations in Western Australia by 6-37% for 0-2month old children, and 30-46% for 3-5month old children, for a range of vaccine effectiveness levels. Our model shows that, provided a vaccine is demonstrated to extend protection against RSV disease beyond the first three months of life, a policy using a maternal RSV vaccine could be effective in reducing RSV hospitalisations in children up to six months of age, meeting the objective of a maternal vaccine in delaying an infant's first RSV infection to an age at which severe disease is less likely.

Probabilistic linkage of national immunisation and state-based health records for a cohort of 1.9 million births to evaluate Australia's childhood immunisation program

Introduction

Several countries have developed national immunisation registers, but only the Nordic countries have linked their registers to other health data in order to comprehensively evaluate the `real world' effectiveness of vaccines. Nordic countries can link datasets deterministically using the national person identifier, but most countries, including Australia, don't have such an identifier to enable this type of linkage.

Objectives

To describe the process for assembling a linked study cohort that will enable the conduct of population-based studies related to immunisation and immunisation policy.

Methods

National death and immunisation databases along with state health data (notifications of vaccine preventable diseases, perinatal data, hospital admissions and emergency department presentations) up until December 2013 were probabilistically linked (using demographic details) for children born between 1996 and 2012 in two states: Western Australia and New South Wales (42% of Australia's population, combined).

Results

After exclusions there were 1.95 million children in the study cohort (live born children with both a birth and perinatal record which represents 97.5% of all live births in the state perinatal data collections - our source population) and 18.0 million person years of follow up (mean: 9.2 years per child). The characteristics of children in the cohort were generally similar to those only included in state perinatal databases and outcome measures were in keeping with expected figures from unlinked data sources. However, the lack of a dynamic national population register meant immigrants could not be included.

Conclusions

We have been able to develop a similarly comprehensive system to the Nordic countries based on probabilistic linkage methods. Our experience should provide encouragement to other countries with national immunisation registers looking to establish similar systems.

Viral Etiology and the Impact of Codetection in Young Children Presenting With Influenza-Like Illness

BACKGROUND

Children with acute respiratory tract infection (ARTI) frequently exhibit virus-virus codetection, yet the clinical significance of ARTI remains contentious. Using data from a prospective cohort of children with influenza-like illness, we examined the virology of ARTI and determined the clinical impact of virus-virus codetection.

METHODS

Children aged 6 to 59 months who presented to a tertiary pediatric hospital between influenza seasons 2008 and 2012 with fever and acute respiratory symptoms were enrolled, and nasal samples were collected. Respiratory viruses were identified by culture and polymerase chain reaction. We compared demographics, presenting symptoms, and clinical outcomes of children with a single-virus infection and those in whom 2 or more viruses were detected (virus-virus codetection). We used logistic regression models and estimated marginal means to calculate the adjusted odds ratios and probabilities of symptom presentation, prescription of antibiotics, and hospitalization.

RESULTS

Of 2356 children, a virus was detected in 1630 (69.2%) of them; rhinovirus (40.8%), influenza (29.5%), and respiratory syncytial virus (26.4%) were detected most commonly. Two or more viruses were detected in 25% of these children. After we adjusted for demographic factors, children with virus-virus codetection had greater odds of presenting with cough (adjusted odds ratio [aOR], 1.9; 95% confidence interval [CI], 1.2-3.1) and rhinorrhea (aOR, 1.8; 95% CI, 1.1-2.9) than those with a single-virus infection, although both symptoms were common. Children with influenza and respiratory syncytial virus combined had the highest probability of hospitalization (55%; 95% CI, 35%-73%), which was significantly greater than for those with influenza infection alone (22%; 95% CI, 16%-29%).

CONCLUSIONS

Overall, virus-virus codetection has limited impact on clinical severity among children with influenza-like illness. However, infection with specific pathogen pairs might be associated with more severe outcomes. Routine diagnostics to identify specific viruses should be restricted to common pathogens.

Using record linkage to validate notification and laboratory data for a more accurate assessment of notifiable infectious diseases

Background

Infectious disease burden is commonly assessed using notification data. Using retrospective record linkage in Western Australia, we described how well notification data captures laboratory detections of influenza, pertussis and invasive pneumococcal disease (IPD).

Methods

We linked data from the Western Australian Notifiable Infectious Diseases Database (WANIDD) and the PathWest Laboratory Database (PathWest) pertaining to the Triple I birth cohort, born in Western Australia in 1996–2012. These were combined to calculate the number of unique cases captured in each dataset alone or in both datasets. To assess the impact of under-ascertainment, we compared incidence rates calculated using WANIDD data alone and using combined data.

Results

Overall, there were 5550 influenza, 513 IPD (2001–2012) and 4434 pertussis cases (2000–2012). Approximately 2% of pertussis and IPD cases and 7% of influenza cases were solely recorded in PathWest. Notification of influenza and pertussis cases to WANIDD improved over time. Overall incidence rates of influenza in children aged <5 years using both datasets was 10% higher than using WANIDD data alone (IRR = 1.1, 95% CI = 1.1–1.2).

Conclusions

This is the first time WANIDD data have been validated against routinely collected laboratory data. We anticipated all cases would be captured in WANIDD but found additional laboratory-confirmed cases that were not notified. Studies investigating pathogen-specific infectious disease would benefit from using multiple data sources.

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-017-0484-7) contains supplementary material, which is available to authorized users.

Effectiveness of seasonal trivalent influenza vaccination against hospital-attended acute respiratory infections in pregnant women: A retrospective cohort study

BACKGROUND

Pregnant women are at risk of serious influenza infection. Although previous studies indicate maternal influenza vaccination can prevent hospitalisation in young infants, there is limited evidence of the effect in mothers.

METHODS

A cohort of 34,701 pregnant women delivering between 1 April 2012 and 31 December 2013 was created using birth records. Principal diagnosis codes from hospital emergency department (ED) and inpatient records were used to identify episodes of acute respiratory illness (ARI) during the 2012 and 2013 southern hemisphere influenza seasons. Cox regression models were used to calculate adjusted hazard ratios (aHRs) by maternal vaccination status, controlling for Indigenous status, socioeconomic level, medical conditions, and week of delivery.

RESULTS

3,007 (8.7%) women received a seasonal influenza vaccine during pregnancy. Vaccinated women were less likely to visit an ED during pregnancy for an ARI (9.7 visits per 10,000 person-days vs. 35.5 visits per 10,000 person-days; aHR: 0.19, 95% CI: 0.05-0.68). Vaccinated women were also less likely to be hospitalised with an ARI compared to unvaccinated women (16.2 hospitalisations per 10,000 person-days vs. 34.0 hospitalisations per 10,000 person-days; aHR: 0.35, 95% CI: 0.13-0.97).

CONCLUSIONS

Influenza vaccination during pregnancy was associated with significantly fewer hospital attendances for ARI in pregnant women.

Time series analysis of RSV and bronchiolitis seasonality in temperate and tropical Western Australia

Respiratory syncytial virus (RSV) causes respiratory illness in young children and is most commonly associated with bronchiolitis. RSV typically occurs as annual or biennial winter epidemics in temperate regions, with less pronounced seasonality in the tropics. We sought to characterise and compare the seasonality of RSV and bronchiolitis in temperate and tropical Western Australia. We examined over 13 years of RSV laboratory identifications and bronchiolitis hospitalisations in children, using an extensive linked dataset from Western Australia. We applied mathematical time series analyses to identify the dominant seasonal cycle, and changes in epidemic size and timing over this period. Both the RSV and bronchiolitis data showed clear winter epidemic peaks in July or August in the southern Western Australia regions, but less identifiable seasonality in the northern regions. Use of complex demodulation proved very effective at comparing disease epidemics. The timing of RSV and bronchiolitis epidemics coincided well, but the size of the epidemics differed, with more consistent peak sizes for bronchiolitis than for RSV. Our results show that bronchiolitis hospitalisations are a reasonable proxy for the timing of RSV detections, but may not fully capture the magnitude of RSV epidemics.

Exploring the dynamics of respiratory syncytial virus (RSV) transmission in children

Respiratory syncytial virus (RSV) is the main cause of lower respiratory tract infections in children. Whilst highly seasonal, RSV dynamics can have either one-year (annual) or two-year (biennial) cycles. Furthermore, some countries show a 'delayed biennial' pattern, where the epidemic peak in low incidence years is delayed. We develop a compartmental model for RSV infection, driven by a seasonal forcing function, and conduct parameter space and bifurcation analyses to document parameter ranges that give rise to these different seasonal patterns. The model is sensitive to the birth rate, transmission rate, and seasonality parameters, and can replicate RSV dynamics observed in different countries. The seasonality parameter must exceed a threshold for the model to produce biennial cycles. Intermediate values of the birth rate produce the greatest delay in these biennial cycles, while the model reverts to annual cycles if the duration of immunity is too short. Finally, the existence of period doubling and period halving bifurcations suggests robust model dynamics, in agreement with the known regularity of RSV outbreaks. These findings help explain observed RSV data, such as regular biennial dynamics in Western Australia, and delayed biennial dynamics in Finland. From a public health perspective, our findings provide insight into the drivers of RSV transmission, and a foundation for exploring RSV interventions.

Systematic review and meta-analysis of respiratory viral coinfections in children

Respiratory infections are a common cause of paediatric morbidity. Clinical outcomes in children hospitalized with single respiratory virus infection are compared with those with two or more viral-viral coinfection. Studies were restricted to those reporting on children aged less than 5 years (PROSPERO CRD#42014009133). Published data to calculate risk ratios (RR) comparing children with single viral infections to coinfection using a random effects model were used. Similar analyses by pathogen pairs and by excluding children with comorbidities were performed. Of 4443 articles reviewed, 19 were included. Overall, no differences in the risk of fever, admission to an intensive care unit (ICU), oxygen use, mechanical ventilation and abnormal radiographs between children with single infection and those with coinfection were found. When analysing only children without comorbidities, the risk of fever (RR = 1.16 to RR = 1.24, 95% confidence intervals (CI) = 1.00-1.55) and ICU admission (RR = 1.08 to RR = 1.31, 95% CI = 0.93-1.83) increased but remained non-significant. Point estimates suggested an increased risk of ICU admission in those coinfected with either respiratory syncytial virus or human metapneumovirus compared with those with single infection but was non-significant. Our findings suggest that coinfection is not associated with increased clinical severity, but further investigations by pathogen pairs are warranted.

Surveillance of antenatal influenza vaccination: validity of current systems and recommendations for improvement

BACKGROUND

Although influenza vaccination is recommended during pregnancy as standard of care, limited surveillance data are available for monitoring uptake. Our aim was to evaluate the validity of existing surveillance in Western Australia for measuring antenatal influenza immunisations.

METHODS

The self-reported vaccination status of 563 women who delivered between April and October 2013 was compared against three passive data collection sources: a state-wide antenatal influenza vaccination database maintained by the Department of Health, a public maternity hospital database, and a private health service database. Sensitivity, specificity, and positive and negative predictive values were calculated for each system using self-report as the "gold standard."

RESULTS

The state-wide antenatal vaccination database detected 45.7 % (95 % CI: 40.1-51.4 %) of influenza vaccinations, the public maternity hospital database detected 66.7 % (95 % CI: 55.1-76.9 %), and the private health service database detected 29.1 % (95 % CI: 20.5-39.4 %). Specificity exceeded 90 % and positive predictive values exceeded 80 % for each system. Sensitivity was lowest for women whose antenatal care was provided by a private obstetrician.

CONCLUSIONS

Existing resources for surveillance of antenatal influenza vaccinations detect 29-67 % of vaccinations. Considering the importance of influenza immunisation as a public health intervention, particularly in pregnant women, improvements to routine monitoring of influenza vaccination is warranted.