COVID-19 Vaccine Uptake by Infection Status in New South Wales, Australia

Using linked public health data from Australia to measure uptake of COVID-19 vaccination by infection status, we found coverage considerably lower among infected than uninfected persons for all ages. Increasing uptake of scheduled doses, including among previously infected persons after the recommended postinfection delay, is needed to reduce COVID-19 illness rates.

Australian hospital paediatricians and nurses' perspectives and practices for influenza vaccine delivery in children with medical comorbidities

INTRODUCTION

Influenza vaccination of children with medical comorbidities is critical due their increased risks for severe influenza disease. In Australia, hospitals are an avenue for influenza vaccine delivery to children with comorbidities but are not always effectively utilised. Qualitative enquiry sought to ascertainment the barriers and enablers for influenza vaccination recommendation, delivery, and recording of these children at Australian hospitals.

METHODS

Semi-structured interviews and discussion group sessions were conducted with paediatricians and nurses at four tertiary paediatric specialist hospitals and two general community hospitals in three Australian states. Transcripts from interviews and group sessions were inductively analysed for themes. The Capability, Opportunity, Motivation, and Behaviour (COM-B) model was used to explore the elements of each theme and identify potential interventions to increase influenza vaccination recommendation and delivery behaviours by providers.

RESULTS

Fifteen discussion sessions with 28 paediatricians and 26 nurses, and nine in-depth interviews (five paediatricians and four nurses) were conducted. Two central thematic domains were identified: 1. The interaction between hospital staff and parents/patients for influenza vaccine recommendation, and 2. Vaccination delivery and recording in the hospital environment. Six themes across these domains emerged detailing the importance of dedicated immunisation services, hospital leadership, paediatricians' vaccine recommendation role, the impact of comorbidities, vaccination recording, and cocooning vaccinations. Supportive hospital leadership, engaged providers, and dedicated immunisation services were identified as essential for influenza vaccination of children with comorbidities in Australian hospital.

CONCLUSION

Recommendation of influenza vaccination for Australian children with comorbidities is impacted by the beliefs of paediatricians and the perceived impact of influenza disease on children's comorbidities. Dedicated immunisation services and supportive hospital leadership were drivers for influenza vaccine delivery at hospitals. Future interventions targeting hospital-based influenza vaccine delivery for children with comorbidities should take a rounded approach targeting providers' attitudes, the hospital environment and leadership support.

How accurately does the Australian Immunisation Register identify children overdue for vaccine doses? A national cross-sectional study

Abstract

The accuracy of data recorded in the Australian Immunisation Register (AIR) is important for assessment of population-level vaccine coverage but has not been assessed nationally since 2001. We undertook a cross-sectional study in five states in 2017 using standard criteria to validate AIR records classified as three months overdue for any vaccine at 12, 24 and 48 months. Of 2,000 records selected for audit, 905 were assessable, of which 124 (14%) were misclassified as overdue (errors). Among 563 general practice (GP) records, 91 (16.1%) were errors. Compared with Victoria (1/99; 1%), errors were significantly higher in Western Australia (11/106; 10.4%), Queensland (13/104; 12.5%), South Australia (23/110; 20.9%) and New South Wales (43/144; 29.9%); p < 0.01 for all. Among 165 council and community health centre providers, the overall error rate (17; 10.3%) was non-significantly lower than for GP providers, with an odds ratio (OR) of 0.6 and a 95% confidence interval (95% CI) of 0.3-1.1, and did not differ between states. Records were transmitted to the AIR by paper-based methods in 13 cases, with significantly higher error rates (7/13; 54%) than for practice management software (77/630; 12.2%); OR 9.8 (95% CI 2.8-36.4) or the AIR secure site (23/87; 26.4%); OR 2.6 (95% CI 1.4-4.5). Accuracy is increasingly important, with mandatory reporting to the AIR for all National Immunisation Program vaccines from July 2021, and best achieved by uniform use of practice management software.

Risk factors and disease severity in Australian infants aged under 6 months hospitalised with influenza 2011-2019

AIM

Infants aged <6 months are vulnerable to severe influenza disease and no vaccine is approved for use in this age group. We aimed to describe the epidemiology, risk factors associated with severe outcomes and management of influenza in Australian infants aged <6 months.

METHODS

Incident cases aged <6 months of laboratory-confirmed influenza were captured through two national active prospective sentinel hospital-based surveillance systems in Australia from 2011 to 2019, inclusive. Demographic and clinical features, disease risk factors and outcomes (intensive care unit (ICU) admission and length of stay) and oseltamivir use were analysed. The proportion of infant influenza hospitalisations and nosocomial cases among all hospitalisations were also reported.

RESULTS

Of 680 hospitalised infants aged <6 months, 57.9% were male and 14.5% were Indigenous Australian. Median age was 2.6 months, 19.2% were born premature and 19.0% had a comorbidity, excluding prematurity. Overall, 77.9% had influenza A. Nosocomial cases accounted for 7.8%. ICU admission occurred in 14.7% and oseltamivir was prescribed for 18.8%. Factors associated with ICU admission included age <1 month (adjusted odds ratio (aOR) 3.95, 95% confidence interval (CI): 1.47-10.60), comorbidity (aOR 7.69, 95% CI: 4.04-14.64) and prematurity (aOR 2.60, 95% CI: 1.40-4.81). The proportion of infants with influenza among all infant hospitalisations ranged 1.0-2.6% in the 2019 influenza season.

CONCLUSION

Infants aged <6 months, and particularly neonates, experience serious disease from influenza. This data underpins the need for preventative strategies such as maternal immunisation and continued investigation into the possibility of safe and efficacious vaccination prior to 6 months of age.

Pertussis Disease and Antenatal Vaccine Effectiveness in Australian Children

BACKGROUND

Population-level studies of severe pertussis extending beyond infancy are sparse, and none in the context of antenatal vaccination. We compared hospitalized pertussis cases from birth to 15 years of age before and after introduction of antenatal immunization.

METHODS

Active surveillance of laboratory-confirmed pertussis hospitalizations in a national network of pediatric hospitals in Australia January 2012 to June 2019. Impact of maternal vaccination was assessed by vaccine effectiveness (VE) in cases and test-negative controls with <2 months of age and by before-after comparison of age distribution of cases. Among cases eligible for one or more vaccine doses, we examined proportions age-appropriately immunized and with comorbidities by age group.

RESULTS

Among 419 eligible cases, the proportion <2 months of age significantly decreased from 33.1% in 2012 to 2014 compared with 19.6% in 2016 to 2019 when mothers of only 4 of 17 (23.5%) cases <2 months of age had received antenatal vaccination. VE was estimated to be 84.3% (95% CI, 26.1-96.7). Across all years (2012-2019), of 55 cases 4-11 months of age, 21 (38%) had ≥2 vaccine doses, whereas among 155 cases ≥12 months of age, 122 (85.2%) had ≥3 vaccine doses. Prevalence of comorbidities (primarily cardiorespiratory) increased from 5 (2.1%) <6 months of age to 36 (24.2%) ≥12 months of age (P < 0.001), with 6/16 (38%) cases ≥12 months of age who required intensive care having comorbidities.

CONCLUSIONS

Below the age of 12 months, prevention of severe pertussis will be maximized by high maternal antenatal vaccine uptake and timeliness of infant vaccine doses. Despite full immunization, we found children ≥12 months of age accounted for 27% of hospitalizations <15 years, with 24% having comorbities, suggesting new vaccine strategies, such as additional doses or more immunogenic vaccines, require evaluation.

Influenza hospitalizations in Australian children 2010-2019: The impact of medical comorbidities on outcomes, vaccine coverage, and effectiveness

BACKGROUND

Children with comorbidities are at greater risk of severe influenza outcomes compared with healthy children. In Australia, influenza vaccination was funded for those with comorbidities from 2010 and all children aged <5 years from 2018. Influenza vaccine coverage remains inadequate in children with and without comorbidities.

METHODS

Children ≤16 years admitted with acute respiratory illness and tested for influenza at sentinel hospitals were evaluated (2010-2019). Multivariable regression was used to identify predictors of severe outcomes. Vaccine effectiveness was estimated using the modified incidence density test-negative design.

RESULTS

Overall, 6057 influenza-confirmed hospitalized cases and 3974 test-negative controls were included. Influenza A was the predominant type (68.7%). Comorbidities were present in 40.8% of cases. Children with comorbidities were at increased odds of ICU admission, respiratory support, longer hospitalizations, and mortality. Specific comorbidities including neurological and cardiac conditions increasingly predisposed children to severe outcomes. Influenza vaccine coverage in influenza negative children with and without comorbidities was low (33.5% and 17.9%, respectively). Coverage improved following introduction of universal influenza vaccine programs for children <5 years. Similar vaccine effectiveness was demonstrated in children with (55% [95% confidence interval (CI): 45; 63%]) and without comorbidities (57% [(95%CI: 44; 67%]).

CONCLUSIONS

Comorbidities were present in 40.8% of influenza-confirmed admissions and were associated with more severe outcomes. Children with comorbidities were more likely experience severe influenza with ICU admission, mechanical ventilation, and in-hospital morality. Despite demonstrated vaccine effectiveness in those with and without comorbidities, vaccine coverage was suboptimal. Interventions to increase vaccination are expected to reduce severe influenza outcomes.

ATAGI 2021 annual statement on immunisation Last updated: 19 September 2021

The Australian Technical Advisory Group on Immunisation (ATAGI) 2021 Annual Statement on Immunisation is the first publication in this series. It highlights the key successes, trends and challenges in the use of vaccines and control of vaccine preventable diseases (VPDs) in Australia in 2020. It also signals ATAGI’s priority actions for addressing key issues for 2021 and beyond.

Paediatric Active Enhanced Disease Surveillance (PAEDS) 2017 and 2018: Prospective hospital-based surveillance for serious paediatric conditions

INTRODUCTION

The Paediatric Active Enhanced Disease Surveillance (PAEDS) network is a hospital-based active surveillance system employing prospective case ascertainment for selected serious childhood conditions, particularly vaccine-preventable diseases and potential adverse events following immunisation (AEFI). This report presents surveillance data for 2017 and 2018.

METHODS

Specialist nurses screened hospital admissions, emergency department (ED) records, laboratory and other data on a daily basis in seven paediatric tertiary referral hospitals across Australia to identify children with the conditions under surveillance. In 2017 and 2018 these included acute flaccid paralysis (AFP; a syndrome associated with poliovirus infection), acute childhood encephalitis (ACE), influenza, intussusception (IS; a potential AEFI with rotavirus vaccines), pertussis, varicella-zoster virus infection (varicella and herpes zoster), invasive meningococcal, and invasive Group A streptococcus diseases. An additional social research component was added to evaluate parental attitudes to vaccination.

RESULTS

PAEDS captured 1,580 and 925 cases for 2017 and 2018, respectively, across all conditions under surveillance. Key outcomes of PAEDS included: contribution to national AFP surveillance to reach the World Health Organization reporting targets; identification of a third human parechovirus outbreak among other infectious diseases linked to ACE; demonstration of variable influenza activity between 2017 and 2018, with vaccine effectiveness (VE) analysis demonstrating that the protection offered through vaccination is season-dependent. All IS cases associated with vaccine receipt were reported to the relevant state health department. Varicella and herpes zoster case numbers remained unchanged, with vaccine uptake found to be suboptimal among eligible children under the NIP. Enhanced pertussis surveillance continues to capture controls for VE estimation. Surveillance for invasive meningococcal disease showed predominance for serotype B at 57% over 2 years among 77 cases where serotyping was available, and surveillance for invasive group A streptococcus captured severe disease in children.

CONCLUSION

PAEDS continues to provide unique policy-relevant data on serious paediatric conditions using hospital-based sentinel surveillance.

Paediatric Active Enhanced Disease Surveillance (PAEDS) 2017 and 2018: Prospective hospital-based surveillance for serious paediatric conditions

Introduction

The Paediatric Active Enhanced Disease Surveillance (PAEDS) network is a hospital-based active surveillance system employing prospective case ascertainment for selected serious childhood conditions, particularly vaccine-preventable diseases and potential adverse events following immunisation (AEFI). This report presents surveillance data for 2017 and 2018.

Methods

Specialist nurses screened hospital admissions, emergency department (ED) records, laboratory and other data on a daily basis in seven paediatric tertiary referral hospitals across Australia to identify children with the conditions under surveillance. In 2017 and 2018 these included acute flaccid paralysis (AFP; a syndrome associated with poliovirus infection), acute childhood encephalitis (ACE), influenza, intussusception (IS; a potential AEFI with rotavirus vaccines), pertussis, varicella-zoster virus infection (varicella and herpes zoster), invasive meningococcal, and invasive Group A streptococcus diseases. An additional social research component was added to evaluate parental attitudes to vaccination.

Results

PAEDS captured 1,580 and 925 cases for 2017 and 2018, respectively, across all conditions under surveillance. Key outcomes of PAEDS included: contribution to national AFP surveillance to reach the World Health Organization reporting targets; identification of a third human parechovirus outbreak among other infectious diseases linked to ACE; demonstration of variable influenza activity between 2017 and 2018, with vaccine effectiveness (VE) analysis demonstrating that the protection offered through vaccination is season-dependent. All IS cases associated with vaccine receipt were reported to the relevant state health department. Varicella and herpes zoster case numbers remained unchanged, with vaccine uptake found to be suboptimal among eligible children under the NIP. Enhanced pertussis surveillance continues to capture controls for VE estimation. Surveillance for invasive meningococcal disease showed predominance for serotype B at 57% over 2 years among 77 cases where serotyping was available, and surveillance for invasive group A streptococcus captured severe disease in children.

Conclusion

PAEDS continues to provide unique policy-relevant data on serious paediatric conditions using hospital-based sentinel surveillance.

Epidemic and Inter-epidemic Burden of Pediatric Human Parechovirus Infection in New South Wales, Australia, 2017-2018

BACKGROUND

Human parechovirus (HPeV) typically infects young children, and although infection is often asymptomatic, some types (eg, HPeV3) are associated with severe clinical manifestations, including central nervous system infection or sepsis-like syndrome, particularly affecting young infants. The third documented national epidemic of HPeV occurred in Australia in 2017-2018.

METHODS

Four public laboratories that perform almost all of the HPeV PCR testing in New South Wales provided data regarding HPeV tests performed from July 1, 2017 to June 30, 2018. Limited demographic and clinical data were obtained from electronic medical records for laboratory test-positive cases that presented to each of the 3 pediatric hospitals in New South Wales.

RESULTS

Five hundred eighty-one HPeV-positive samples obtained from 395 cases were included in the analysis. The peak of the outbreak occurred in late November 2017 (approximately 35 new cases each week), with the main HPeV epidemic occurring between the spring and summer months of September 2017 to January 2018; although this seasonality was observed primarily in infants less than 12 months of age. Among the 388 pediatric cases, almost half were younger than 2 months (188; 47%) and only 10 were children older than 2 years. The annualized estimated incidence of laboratory confirmed HPeV infection in children was approximately 142.4 cases per 100,000 children younger than 5 years in New South Wales during the epidemic season.

CONCLUSIONS

The large burden of HPeV infection and disease identified in young infants in this and previous Australian studies highlight the need for more comprehensive national surveillance of HPeV infections and improved prevention strategies.

Influenza Epidemiology, Vaccine Coverage and Vaccine Effectiveness in Children Admitted to Sentinel Australian Hospitals in 2017: Results from the PAEDS-FluCAN Collaboration

BACKGROUND

In 2017, Australia experienced record influenza notifications. Two surveillance programs combined to summarize the epidemiology of hospitalized influenza in children and report on vaccine effectiveness (VE) in the context of a limited nationally funded vaccination program.

METHODS

Subjects were prospectively recruited (April-October 2017). Case patients were children aged ≤16 years admitted to 11 hospitals with an acute respiratory illness and laboratory-confirmed influenza. Controls were hospitalized with acute respiratory illness and tested negative for influenza. VE estimates were calculated using the test-negative design.

RESULTS

A total of 1268 children were hospitalized with influenza: 31.5% were <2 years old, 8.3% were indigenous, and 45.1% had comorbid conditions predisposing to severe influenza. Influenza B was detected in 34.1% with influenza A/H1N1 and A/H3N2 detected in 47.2% and 52.8% of subtyped influenza A specimens. The median length of stay was 3 days (interquartile range, 1-5), 14.5% were admitted to the intensive care unit, and 15.9% received oseltamivir. Four in-hospital deaths occurred (0.3%): one was considered influenza associated. Only 17.1% of test-negative-controls were vaccinated. The VE of inactivated quadrivalent influenza vaccine for preventing hospitalized influenza was estimated at 30.3% (95% confidence interval, 2.6%-50.2%).

CONCLUSIONS

Significant influenza-associated morbidity was observed in 2017 in Australia. Most hospitalized children had no comorbid conditions. Vaccine coverage and antiviral use was inadequate. Influenza vaccine was protective in 2017, yet VE was lower than previous seasons. Multiple Australian states have introduced funded preschool vaccination programs in 2018. Additional efforts to promote vaccination and monitor effectiveness are required.

Comparative Postmarket Safety Profile of Adjuvanted and High-Dose Influenza Vaccines in Individuals 65 Years or Older

IMPORTANCE

Every year, influenza vaccines are administered to millions of people worldwide to reduce morbidity and mortality from influenza. As new vaccine formulations are increasingly used, monitoring and comparing safety, in addition to vaccine effectiveness, in target populations are essential.

OBJECTIVE

To assess the postmarketing safety profile of 2018 Southern Hemisphere influenza vaccines, particularly 2 new enhanced trivalent inactivated influenza vaccines: an adjuvanted trivalent inactivated influenza vaccine (aIIV3) and high-dose trivalent inactivated influenza vaccine (HD-IIV3), among Australian individuals 65 years or older.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used solicited short message service-based self-reported survey data on adverse events occurring within 3 to 5 days after receipt of an influenza vaccination. Participants included individuals 65 years or older who received routinely recommended influenza vaccines at 1 of 265 sentinel immunization sites, including primary care, hospital, and community-based clinics, participating in Australia's AusVaxSafety active vaccine safety surveillance system from April 1 to August 31, 2018. Data were analyzed from September 1, 2018, to June 30, 2019.

EXPOSURE

Any licensed 2018 influenza vaccine administered in clinical practice.

MAIN OUTCOMES AND MEASURES

Rates (overall, by brand, and by concomitant vaccine receipt) of adverse events, including medical attendance as a proxy for serious adverse events.

RESULTS

Of 72 013 individuals 65 years or older who received an influenza vaccine in 2018, 50 134 individuals (69.6%) responded to the initial survey regarding adverse events experienced after vaccination (median [interquartile range] age, 71 [68-76] years; 27 056 [54.0%] women). Most individuals received an enhanced trivalent inactivated influenza vaccine, including 28 003 individuals (55.9%) who received aIIV3 and 19 306 individuals (38.5%) who received HD-IIV3; 2208 individuals (4.4%) received a quadrivalent inactivated influenza vaccine. Individuals who received HD-IIV3 reported significantly higher rates of any adverse event compared with individuals who received aIIV3 (1716 individuals [8.9%] vs 1796 individuals [6.4%]; P < .001) as well as specific adverse events, including fever (195 individuals [1.1%] vs 164 individuals [0.6%]; P < .001), injection site pain (383 individuals [2.1%] vs 350 individuals [1.3%]; P < .001), and injection site swelling or redness (256 individuals [1.4%] vs 248 individuals [0.9%]; P < .001). Adverse event rates reported by those receiving any quadrivalent inactivated influenza vaccine were similar to rates reported by those receiving aIIV3. Rates of medical care seeking for adverse events associated with aIIV3 and HD-IIV3 were low and comparable (80 individuals [0.3%] vs 56 individuals [0.3%]; P = .91).

CONCLUSIONS AND RELEVANCE

The findings of this large-scale participant-based postmarketing assessment of the safety of 2 new enhanced influenza vaccines used in individuals 65 years or older provide reassuring near-real-time and cumulative data to inform and support confidence in ongoing vaccine use.

The impact of new universal child influenza programs in Australia: Vaccine coverage, effectiveness and disease epidemiology in hospitalised children in 2018

BACKGROUND

New jurisdictionally-based vaccination programs were established providing free quadrivalent influenza vaccine (QIV) for preschool Australian children in 2018. This was in addition to the National Immunisation Program (NIP) funded QIV for Indigenous children and children with comorbid medical conditions. We assessed the impact of this policy change on influenza disease burden and vaccine coverage, as well as report on 2018 vaccine effectiveness in a hospital-based surveillance system.

METHODS

Subjects were recruited prospectively from twelve PAEDS-FluCAN sentinel hospital sites (April until October 2018). Children aged ≤16 years hospitalised with an acute respiratory illness (ARI) and laboratory-confirmed influenza were considered cases. Hospitalised children with ARI who tested negative for influenza were considered controls. VE estimates were calculated from the adjusted odds ratio of vaccination in cases and controls.

RESULTS

A total of 458 children were hospitalised with influenza: 31.7% were <2 years, 5.0% were Indigenous, and 40.6% had medical comorbidities predisposing to severe influenza. Influenza A was detected in 90.6% of children (A/H1N1: 38.0%; A/H3N2: 3.1%; A/unsubtyped 48.6%). The median length of stay was 2 days (IQR: 1,3) and 8.1% were admitted to ICU. Oseltamivir use was infrequent (16.6%). Two in-hospital deaths occurred (0.45%). 12.0% of influenza cases were vaccinated compared with 36.0% of test-negative controls. Vaccine effectiveness of QIV for preventing influenza hospitalisation was estimated at 78.8% (95%CI: 66.9; 86.4).

CONCLUSIONS

Compared with 2017 (n = 1268 cases), a significant reduction in severe influenza was observed in Australian children, possibly contributed to by improved vaccine coverage and high vaccine effectiveness. Despite introduction of jurisdictionally-funded preschool programs and NIP-funded vaccine for children with risk factors for severe disease, improved coverage is required to ensure adequate protection against paediatric influenza morbidity and mortality.

SCN1A Variants in vaccine-related febrile seizures: A prospective study

OBJECTIVE

Febrile seizures may follow vaccination. Common variants in the sodium channel gene, SCN1A, are associated with febrile seizures, and rare pathogenic variants in SCN1A cause the severe developmental and epileptic encephalopathy Dravet syndrome. Following vaccination, febrile seizures may raise the specter of poor outcome and inappropriately implicate vaccination as the cause. We aimed to determine the prevalence of SCN1A variants in children having their first febrile seizure either proximal to vaccination or unrelated to vaccination compared to controls.

METHODS

We performed SCN1A sequencing, blind to clinical category, in a prospective cohort of children presenting with their first febrile seizure as vaccine proximate (n = 69) or as non-vaccine proximate (n = 75), and children with no history of seizures (n = 90) recruited in Australian pediatric hospitals.

RESULTS

We detected 2 pathogenic variants in vaccine-proximate cases (p.R568X and p.W932R), both of whom developed Dravet syndrome, and 1 in a non-vaccine-proximate case (p.V947L) who had febrile seizures plus from 9 months. All had generalized tonic-clonic seizures lasting >15 minutes. We also found enrichment of a reported risk allele, rs6432860-T, in children with febrile seizures compared to controls (odds ratio = 1.91, 95% confidence interval = 1.31-2.81).

INTERPRETATION

Pathogenic SCN1A variants may be identified in infants with vaccine-proximate febrile seizures. As early diagnosis of Dravet syndrome is essential for optimal management and outcome, SCN1A sequencing in infants with prolonged febrile seizures, proximate to vaccination, should become routine. ANN NEUROL 2020;87:281-288.

Evolutionary analysis of human parechovirus type 3 and clinical outcomes of infection during the 2017-18 Australian epidemic

Human parechovirus type 3 (HPeV3) can cause severe sepsis-like illness in young infants and may be associated with long term neurodevelopmental delay later in childhood. We investigated the molecular epidemiology of HPeV infection in thirty three infants requiring hospitalization before, during and after the peak of the 2017/18 HPeV epidemic wave in Australia. During the peak of the epidemic, all cases were infected with an HPeV3, while before and after the peak, HPeV1 was the predominant type detected. The predominant HPeV3 was the recombinant HPeV3 also detected in the 2013/14 and 2015/16 Australian epidemics. Sepsis-like or meningitis-like symptoms were only reported in cases infected with the recombinant HPeV3. Phylogenetic analysis of the recombinant HPeV3 revealed that the virus continued to evolve, also between the Australian outbreaks, thus indicating continued circulation, despite not being detected and reported in Australia or elsewhere in between epidemic waves. The recombinant HPeV3 continued to show a remarkable stability in its capsid amino acid sequence, further strengthening our previous argument for development of a vaccine or immunotherapeutics to reduce the severity of HPeV3 outbreaks due to this virus.

Varicella vaccine effectiveness over 10 years in Australia; moderate protection from 1-dose program

OBJECTIVES

To examine the impact of Australia's single dose infant varicella vaccination program, we assessed single dose varicella vaccine effectiveness (VE) in preventing hospitalised disease using two methods.

METHODS

Clinically confirmed varicella cases from the Paediatric Active Enhanced Disease Surveillance (PAEDS) sentinel network were age-matched to 20 controls obtained from the Australian Immunisation Register. Conditional logistic regression models were used to estimate VE and compared with estimates obtained using our second approach.

RESULTS

There were 78 hospitalised varicella cases during the post vaccine introduction period from January 2008 to December 2015, who were eligible for funded varicella vaccination. Median age at onset was 4.5 years and more than half (59%) were vaccinated. The majority of children received one vaccine brand (Varilrix, GSK). The estimated case-control VE for one dose of vaccine against hospitalised varicella was 64.7% (95% CI: 43.3-78.0%); estimates using the screening method were not significantly different. Exclusion of children who were immunocompromised did not significantly alter VE estimates.

CONCLUSIONS

Although Australia's program has impacted on the burden of varicella disease, single dose VE against varicella hospitalisation is only moderate. Greater reductions in varicella disease could potentially be achieved by incorporation of a second vaccine dose into the program to minimise breakthrough disease and interrupt virus circulation.

Active surveillance of 2017 seasonal influenza vaccine safety: an observational cohort study of individuals aged 6 months and older in Australia

OBJECTIVE

To actively solicit adverse events experienced in the days following immunisation with quadrivalent inactivated influenza vaccine using Australia's near real-time, participant-based vaccine safety surveillance system, AusVaxSafety.

DESIGN AND SETTING

Observational cohort study conducted in 194 sentinel surveillance immunisation sites (primary care, hospital and community-based clinics) across Australia.

PARTICIPANTS

Individuals aged ≥6 months who received a routine seasonal influenza vaccine at a participating site (n=102 911) and responded to a survey (via short message service or email) sent 3 days after vaccination about adverse events experienced (n=73 892; 71.8%).

MAIN OUTCOME MEASURE

Near real-time and cumulative participant-reported rates of any adverse event, fever or medical attendance experienced within 3 days after vaccination overall, by brand, age, pregnancy status and concomitant vaccine receipt.

RESULTS

Participant median age was 57 years (range: 6 months to 102 years); 58.1% (n=42 869) were female and 2.7% (n=2018) were pregnant. Near real-time fast initial response cumulative summation and Bayesian analyses of weekly event rates did not demonstrate a safety signal. Children aged 6 months to 4 years had higher event rates (522/6180; 8.4%) compared with older ages; participants aged ≥65 years reported fewer events (1695/28 154; 6.0%). There were no clinically significant differences in safety between brands, by age group or overall. Cumulative data analysis demonstrated that concomitant vaccination was associated with increased rates of fever (2.1% vs 0.8%) and medical attendance (0.8% vs 0.4%), although all rates were low and did not exceed expected levels.

CONCLUSIONS

Novel, postmarketing AusVaxSafety surveillance demonstrated comparable and expected safety outcomes for the 2017 quadrivalent inactivated influenza vaccine brands used in Australia. These near real-time, participant-reported data are expected to encourage confidence in vaccine safety and promote uptake.

Systematic Review and Meta-analysis of Indirect Protection Afforded by Vaccinating Children Against Seasonal Influenza: Implications for Policy

Background

Universal childhood vaccination is a potential solution to reduce seasonal influenza burden.

Methods

We reviewed systematically the literature on "herd"/indirect protection from vaccinating children aged 6 months to 17 years against influenza.

Results

Of 30 studies included, 14 (including 1 cluster randomized controlled trial [cRCT]) used live attenuated influenza vaccine, 11 (7 cRCTs) used inactivated influenza vaccine, and 5 (1 cRCT) compared both vaccine types. Twenty of 30 studies reported statistically significant indirect protection effectiveness (IPE) with point estimates ranging from 4% to 66%. Meta-regression suggests that studies with high quality and/or sufficiently large sample size are more likely to report significant IPE. In meta-analyses of 6 cRCTs with full randomization (rated as moderate quality overall), significant IPE was found in 1 cRCT in closely connected communities where school-aged children were vaccinated: 60% (95% confidence interval [CI], 41%-72%; I2 = 0%; N = 2326) against laboratory-confirmed influenza, and 3 household cRCTs in which preschool-aged children were vaccinated: 22% (95% CI, 1%-38%; I2 = 0%; N = 1903) against acute respiratory infections or influenza-like illness. Significant IPE was also reported in a large-scale cRCT (N = 8510) that was not fully randomized, and 3 ecological studies (N > 10000) of moderate quality including 36% reduction in influenza-related mortality among the elderly in a Japanese school-based program. Data on IPE in other settings are heterogeneous and lacked power to draw a firm conclusion.

Conclusions

The available evidence suggests that influenza vaccination of children confers indirect protection in some but not all settings. Robust, large-scaled studies are required to better quantify the indirect protection from vaccinating children for different settings/endpoints.

Australian rubella serosurvey 2012-2013: On track for elimination?

BACKGROUND

The World Health Organization has targeted rubella virus for elimination regionally. Australia was one of the first countries to implement a nationally funded rubella immunisation program, in 1971, and conducts regular national rubella serosurveillance studies. We aimed to estimate the seroprevalence of rubella-specific IgG antibody in the Australian population by age and sex in 2012-2013, to compare the results with three previous serosurveys conducted in 1996-1999, 2002 and 2007 and to estimate the effective reproduction numbers (R_n).

METHODS

This study used 2729 serum and plasma specimens, randomly selected from a specimen bank collected in 2012-2013 across Australia. Age groups included in the sample ranged from 1 to 49 years. Sera were tested for rubella-specific IgG-antibody using the Enzygnost anti-rubella IgG enzyme immunoassay and classified as positive, negative or equivocal according to rubella-specific IgG concentrations of >7 IU/ml, <3 IU/ml and 3-7 IU/ml, respectively.

RESULTS

The overall proportions seropositive, seronegative and equivocal for rubella-specific IgG were 92.1% (95% CI, 91.0-93.2), 6.7% (95% CI, 5.7-7.7) and 1.2% (95% CI, 0.8-1.6), respectively. The proportion of males seropositive was significantly lower than females in the 30-34 (83.1% vs. 96.8%, p = 0.003), 35-39 (86.1% vs. 96.3%, p = 0.02) and 40-44 (86.1% vs. 95.7%, p = 0.03) year age groups. R_n for rubella in 2012-2013 was estimated to be 0.33 (95% CI 0.28-0.39).

DISCUSSION

The 2012-2013 national serosurvey showed levels of rubella-specific IgG seropositivity in the Australian population are relatively high with no evidence of decrease compared to previous serosurveys conducted in 1996-1999, 2002 and 2007. The lower proportion of seropositive males aged 30-44 years likely reflects the initial immunisation program targeting females only. To our knowledge this study represents the longest period of serosurveillance following introduction of a nationally funded rubella immunisation program. The lack of evidence of decreasing rubella-specific IgG seropositivity is therefore reassuring for Australia and other countries with longstanding high vaccine coverage.

Repeated Vaccination Does Not Appear to Impact Upon Influenza Vaccine Effectiveness Against Hospitalization With Confirmed Influenza

Background.

Annual influenza vaccine is recommended for those at greatest risk of severe influenza infection. Recent reports of a negative impact of serial influenza vaccination on vaccine effectiveness (VE) raises concerns about the recommendation for annual influenza vaccines, particularly in persons at greatest risk.

Methods.

The Influenza Complications Alert Network (FluCAN) is an Australian hospital-based sentinel surveillance program. In this observational study, cases were defined as subjects aged >9 years admitted with influenza confirmed by polymerase chain reaction. Controls were subjects with acute respiratory illness testing negative for influenza. Propensity scores were used to adjust for the likelihood of being vaccinated. VE was calculated as 1 - adjusted odds ratio of vaccination in cases compared with test-negative controls.

Results.

Over 2010-2015, 6223 cases and 6505 controls were hospitalized with confirmed influenza and influenza test-negative acute respiratory illness, respectively. Following stratification by quintile of propensity score, site, and year, VE was estimated to be 43% (95% confidence interval [CI], 37%-49%) overall. VE was estimated to be 51% (95% CI, 45%-57%) in those vaccinated in both the current and previous season, compared with 33% (95% CI, 17%-47%) vaccinated in the current season only and 35% (95% CI, 21%-46%) in the previous season only. Similar results were observed for influenza A/H1N1, influenza A/H3N2, and influenza B strains.

Conclusions.

Vaccination in both the current and previous seasons was associated with a higher VE against hospitalization with influenza than vaccination in either single season. These findings reinforce current recommendations for annual influenza vaccination, particularly those at greatest risk of influenza disease.

Evaluation of bacille Calmette-Guérin immunisation programs in Australia

bacille Calmette-Guérin (BCG) immunisation programs in Australia are funded and operated by the individual states and territories. In recent years BCG vaccine shortages have required use of unregistered products. We aimed to evaluate BCG immunisation programs in Australia, with particular reference to program implementation and national consistency.
 Methods: Between September and November 2015, 12 key stakeholders, representing Australian states and territories, completed surveys. We analysed BCG vaccination coverage data from the Australian Childhood Immunisation Register (ACIR), and data on adverse events following immunisation (AEFI) with BCG vaccine from the Therapeutic Goods Administration's Adverse Drug Reactions System, for 2001 to 2014.
 Results: Access to BCG vaccination varies between jurisdictions, with some states providing this only in major city locations. Analysis of ACIR data suggests significant differences in vaccine delivery between jurisdictions, but varying levels of under-reporting to the ACIR were also acknowledged. The rate of BCG AEFI appeared to increase between 2011 and 2014; however, these data need to be interpreted with caution due to small numbers, likely under-reporting of both numerator (AEFI) and denominator (vaccine doses administered), and the general increase in reporting of AEFI related to other vaccines in children over this period.
 Conclusions: BCG immunisation programs aim to prevent severe forms of tuberculosis in young children who live in or travel to high burden settings. A range of factors, particularly inconsistent vaccine supply are leading to low, variable and inequitable vaccine delivery across Australian jurisdictions. Improved BCG vaccination uptake and AEFI data quality are required for accurate monitoring of program delivery and vaccine safety - this is particularly important given the current need to use unregistered vaccines. Improved and consistent access to BCG vaccine is suggested to optimise equity for at-risk children Australia-wide.

Adverse events following immunisation with bacille Calmette-Guérin vaccination: baseline data to inform monitoring in Australia following introduction of new unregistered BCG vaccine

In recent years there has been a global shortage of bacille Calmette-Guérin (BCG) vaccine and, from September 2012, unregistered vaccines have needed to be used in Australia (a Danish product initially until the end of 2015, and a Polish product used in some jurisdictions from early 2016). We examined rates and types of adverse events following immunisation (AEFI) with BCG vaccine reported to the Therapeutic Goods Administration between 2009 and 2014 in children aged less than 7 years. Reporting rates of AEFI with BCG vaccine increased from 87 per 100,000 doses (registered Sanofi Pasteur product) in 2009 to 201 per 100,000 doses (unregistered Danish Statens Serum Institute product) in 2014, with Victoria having the highest rate each year. Substantial variation between jurisdictions exists, suggesting differential reporting of BCG vaccine doses administered and/or BCG vaccine-related AEFI. The most commonly reported reactions were abscess (31%), injection site reaction (27%) and lymphadenopathy/lymphadenitis (17%). This study provides baseline data on BCG vaccine safety to inform surveillance. Given the current use of unregistered vaccines in the context of vaccine supply issues, improved recording of both administered BCG vaccine doses and the reporting of BCG vaccine-related AEFI are required to facilitate close monitoring of vaccine safety.

Influenza epidemiology in patients admitted to sentinel Australian hospitals in 2015: the Influenza Complications Alert Network

The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance program that operates at sites in all states and territories in Australia. This report summarises the epidemiology of hospitalisations with laboratory-confirmed influenza during the 2015 influenza season. In this observational study, cases were defined as patients admitted to one of the sentinel hospitals with an acute respiratory illness with influenza confirmed by nucleic acid detection. During the period 1 April to 30 October 2015 (the 2015 influenza season), 2,070 patients were admitted with confirmed influenza to one of 17 FluCAN sentinel hospitals. Of these, 46% were elderly (≥ 65 years), 15% were children (< 16 years), 5% were Indigenous Australians, 2.1% were pregnant and 75% had chronic co-morbidities. A high proportion were due to influenza B (51%). There were a large number of hospital admissions detected with confirmed influenza in this national observational surveillance system in 2015 with case numbers similar to that reported in 2014. The national immunisation program is estimated to avert 46% of admissions from confirmed influenza across all at-risk groups, but more complete vaccination coverage in target groups could further reduce influenza admissions by as much as 14%.

Australian vaccine preventable disease epidemiological review series: Influenza 2006 to 2015

INTRODUCTION

Influenza is a major contributor to the preventable health burden of Australians each year. The National Immunisation Program provides influenza vaccine for those at highest risk of severe disease. This review of influenza epidemiology examines current data on influenza disease burden in Australia, in the context of several comparable countries having programs with much broader eligibility for influenza vaccine in children.

METHODS

Influenza notifications (2006-2015), hospitalisations, and deaths (2006-2013) were sourced and age-specific rates calculated. Comparisons were made across age groups in the pre-pandemic, pandemic, and post-pandemic periods and by Indigenous and non-Indigenous status.

RESULTS

The 2009 pandemic year and the 2012 non-pandemic season resulted in the highest rates of notification, hospitalisation and death. Influenza notification rates were 4.0 times higher and hospitalisation rates 2.1 times higher during 2011-2013 compared with 2006-2008. Death rates varied widely, but peaks corresponded to high-activity seasons. Influenza hospitalisation rates were highest among those aged <5 and ≥65 years, but influenza-attributable deaths were identified primarily in those aged ≥75 years. Significantly higher notification and hospitalisation rates were seen for all Indigenous people, but higher death rates were largely restricted to the 2009 pandemic year.

CONCLUSIONS

Based on notifications, hospitalisations and deaths, burden of disease from influenza is highest at the extremes of life and is significantly higher among Indigenous people of all ages. This pattern of disease burden warrants consideration of widened eligibility for influenza vaccine under the National Immunisation Program to all Indigenous people and all children less than 5 years of age.

Paediatric Active Enhanced Disease Surveillance inaugural annual report, 2014

INTRODUCTION

The Paediatric Active Enhanced Disease Surveillance (PAEDS) network is a hospital-based active surveillance system employing prospective case ascertainment of selected uncommon vaccine preventable diseases and potential adverse events following immunisation (AEFI). PAEDS enhances other Australian surveillance systems by providing prospective detailed clinical and laboratory data for the same child.

METHODS

Specialist surveillance nurses screen hospital admissions, emergency department records, laboratory and other data, to prospectively identify hospitalised children aged under 15 years in 5 paediatric tertiary referral hospitals in New South Wales, Victoria, South Australia, Western Australia and Queensland. Standardised protocols and case definitions are used across all sites. Conditions under surveillance include vaccine preventable diseases: acute flaccid paralysis, varicella, pandemic and seasonal influenza and pertussis, and potential AEFIs: febrile seizures and intussusception. PAEDS also conducts surveillance for acute childhood encephalitis.

RESULTS

Since August 2007, PAEDS has recruited a total of 6,227 hospitalised cases in total, for all conditions. From January to December 2014, there were 1,220 cases recruited across all conditions. Key outcomes include: enhanced acute flaccid paralysis surveillance to reach World Health Organization targets; supporting varicella and influenza vaccination in children; confirmation of a known low risk of febrile seizures following the 1st dose of measles-mumps-rubella vaccine but no increased risk of febrile seizures after measles-mumps-rubella-varicella vaccine, and a slightly increased risk of developing intussusception 1-7 days after rotavirus vaccination in infants aged less than 3 months. Acute childhood encephalitis data facilitated rapid investigation and response to the enterovirus 71 outbreak in 2013-2014.

CONCLUSIONS

PAEDS provides unique policy-relevant data. This is the first of planned PAEDS annual reports to Communicable Diseases Intelligence.

Surveillance of adverse events following immunisation in Australia annual report, 2014

This report summarises Australian passive surveillance data for adverse events following immunisation (AEFI) for 2014 reported to the Therapeutic Goods Administration for 2014 and describes reporting trends over the 15-year period 1 January 2000 to 31 December 2014. There were 3,087 AEFI records for vaccines administered in 2014; an annual AEFI reporting rate of 13.2 per 100,000 population. There was a decline of 5% in the overall AEFI reporting rate in 2014 compared with 2013. This decline in reported adverse events in 2014 compared with the previous year was mainly attributable to fewer reports following the human papillomavirus (HPV) vaccine as it was the 2nd year of the extension of the National HPV Vaccination Program to males. AEFI reporting rates for most vaccines were lower in 2014 compared with 2013. The most commonly reported reactions were injection site reaction (27%), pyrexia (18%), rash (16%), vomiting (9%), headache (7%), and syncope (5%). The majority of AEFI reports described non-serious events while 7% (n=211) were classified as serious. There were 5 deaths reported with no clear causal relationship with vaccination found.

Influenza epidemiology, vaccine coverage and vaccine effectiveness in children admitted to sentinel Australian hospitals in 2014: the Influenza Complications Alert Network (FluCAN)

The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance programme operating in all states and territories in Australia. We summarise the epidemiology of children hospitalised with laboratory-confirmed influenza in 2014 and reports on the effectiveness of inactivated trivalent inactivated vaccine (TIV) in children. In this observational study, cases were defined as children admitted with acute respiratory illness (ARI) with influenza confirmed by PCR. Controls were hospitalised children with ARI testing negative for influenza. Vaccine effectiveness (VE) was estimated as 1 minus the odds ratio of vaccination in influenza positive cases compared with test-negative controls using conditional logistic regression models. From April until October 2014, 402 children were admitted with PCR-confirmed influenza. Of these, 28% were aged < 1 year, 16% were Indigenous, and 39% had underlying conditions predisposing to severe influenza. Influenza A was detected in 90% of cases of influenza; influenza A(H1N1)pdm09 was the most frequent subtype (109/141 of subtyped cases) followed by A(H3N2) (32/141). Only 15% of children with influenza received antiviral therapy. The adjusted VE of one or more doses of TIV for preventing hospitalised influenza was estimated at 55.5% (95% confidence intervals (CI): 11.6–77.6%). Effectiveness against influenza A(H1N1)pdm09 was high (91.6% , 95% CI: 36.0–98.9%) yet appeared poor against H3N2. In summary, the 2014 southern hemisphere TIV was moderately effective against severe influenza in children. Significant VE was observed against influenza A(H1N1)pdm09.

The effectiveness of influenza vaccination in preventing hospitalisation in children in Western Australia

BACKGROUND

There is increasing evidence demonstrating influenza vaccine effectiveness (VE) in the prevention of influenza in children, including the very young. Data demonstrating the effectiveness against severe disease, including hospitalisation, are limited. We aimed to determine the VE of the southern hemisphere trivalent inactivated influenza vaccine (TIV) in preventing laboratory-confirmed influenza-associated hospitalisation in children.

PATIENTS AND METHODS

Laboratory records were used to identify children with confirmed influenza hospitalised (i.e., cases) during a 5 year period (2008, 2010-2013) at the only tertiary paediatric facility in Western Australia. Cases and time, age and ward matched controls were retrospectively reviewed to determine risk factors, vaccination status and outcome. Adjusted odds ratios and VE estimates were derived using conditional logistic regression models.

RESULTS

Three hundred and eighty five cases were identified (Influenza A, 64.9%; Influenza B, 35.1%). Influenza-like illness and pneumonia were the most frequent presentation (74.5% and 23.9%, respectively). The median length of stay was 2 days (Interquartile range 1-4 days). Twenty children (5.2%) required admission to the intensive care unit. Vaccine uptake in cases and controls was low (4.9% and 8.5%, respectively). Three hundred and six case-control pairs were included in the VE analysis, of which 19 pairs were informative with discrepant vaccination status. VE (fully vaccinated vs. unvaccinated) was estimated to be 62.3% (95% CI: -6.6%, 86.7%).

CONCLUSION

In this study, the point estimate for the effectiveness of TIV in preventing influenza-associated hospitalisation in children was similar to that reported for emergency or outpatient attended, laboratory-confirmed influenza, yet confidence intervals were wide. Vaccine uptake remains low. Studies, enroling larger numbers of children, ideally with higher vaccine uptake, are needed to provide additional evidence on TIV protection against influenza hospitalisation in children.

Systematic review of fever, febrile convulsions and serious adverse events following administration of inactivated trivalent influenza vaccines in children

In 2010, increased febrile convulsions (FC) occurred after administration of inactivated trivalent influenza vaccine (TIV) in Australia. We systematically reviewed the rates of fever, FC and serious adverse events (SAEs) after TIV, focussing on published and unpublished clinical trial data from 2005 to 2012, and performed meta-analysis of fever rates. From 4,372 records in electronic databases, 18 randomised controlled trials (RCTs), 14 non-randomised clinical trials, six observational studies and 12 registered trials (five RCTs and seven non-randomised) were identified. In published RCTs, fever ≥ 38 °C rates after first dose of non-adjuvanted TIV were 6.7% and 6.9% for children aged 6–35 months and ≥ 3 years, respectively. Analysis of RCTs by vaccine manufacturer showed pooled fever estimates up to 5.1% with Sanofi or GlaxoSmithKline vaccines; bioCSL vaccines were used in two non-randomised clinical trials and one unpublished RCT and were associated with fever in 22.5–37.1% for children aged 6–35 months. In RCTs, FCs occurred at a rate of 1.1 per 1,000 vaccinated children. While most TIVs induced acceptably low fever rates, bioCSL influenza vaccines were associated with much higher rates of fever in young children. Future standardised study methodology and access to individual level data would be illuminating.

Febrile seizures following measles and varicella vaccines in young children in Australia

BACKGROUND

Febrile seizures (FS) are common in childhood with incidence peaking in the second year of life when measles and varicella-containing vaccines are administered. This study aimed to examine the vaccine-attributable risk of FS following separate administration of MMR and monovalent varicella vaccines (VV) prior to a planned change to MMRV as the second dose of measles-containing vaccine at 18 months of age.

METHODS

All FS cases in children aged <5 years from 1st January 2012 to 30th April 2013 were identified from emergency department (ED) and inpatient databases at five Australian tertiary paediatric hospitals participating in PAEDS (Paediatric Active Enhanced Disease Surveillance). Immunization records were obtained from the Australian Childhood Immunization Register (ACIR). The relative incidence (RI) of FS following MMR dose 1 (MMR1) and VV in children aged 11-23 months was determined using the self-controlled case series (SCCS) method and used to calculate attributable risk.

RESULTS

There were 2013 FS episodes in 1761 children. The peak age at FS was 18 months. The risk of FS was significantly increased 5-12 days post receipt of MMR1 at 12 months (RI=1.9 [95% CI: 1.3-2.9]), but not after VV at 18 months (RI=0.6 [95% CI: 0.3-1.2]. The estimated excess annual number of FS post MMR1 was 24 per 100,000 vaccinated children aged 11-23 months (95% CI=7-49 cases per 100,000) or 1 per 4167 doses.

CONCLUSIONS

Our study detected the expected increased FS risk post MMR1 vaccine at 12 months, but monovalent varicella vaccine at age 18 months was not associated with increased risk of FS. This provides baseline data to assess the risk of FS post MMRV, introduced in Australia as the second dose of measles-containing vaccine at 18 months of age in July 2013.

Varicella and herpes zoster hospitalizations before and after implementation of one-dose varicella vaccination in Australia: an ecological study

OBJECTIVE

To examine trends in varicella and herpes zoster (HZ) hospitalization following the availability and subsequent National Immunization Programme funding of one-dose varicella vaccination in Australia.

METHODS

Varicella vaccination coverage for children born between 2001 and 2009 was obtained from the Australian Childhood Immunization Register. Principal or any coded varicella or HZ hospitalizations were retrieved from the national hospital morbidity database from 1998 to 2010. Trends in hospitalization rates in different age groups and indigenous status were assessed. Incidence rate ratios (IRR) were calculated between periods before and after implementation of immunization programme funding.

FINDINGS

In the first year of the funded immunization programme, varicella vaccine coverage reached 75% in children aged 24 months and more than 80% in children aged 60 months. Compared with the pre-vaccine period, varicella hospitalization rates during the funded programme were significantly lower for age groups younger than 40 years; with the greatest reduction in children aged 18-59 months (IRR: 0.25; 95% confidence interval, CI: 0.22-0.29). Indigenous children had a higher varicella hospitalization rate compared with non-indigenous children before vaccine implementation (IRR: 1.9; 95% CI: 1.4-2.7), but afterwards reached equivalence (IRR: 1.1; 95% CI: 0.7-1.6). The age-standardized HZ hospitalization rate declined between the periods (IRR: 0.95; 95% CI: 0.92-0.97).

CONCLUSION

Rapid attainment of high coverage reduced varicella hospitalizations in the targeted age group, particularly for indigenous children, but also in non-targeted age groups, with no increase in HZ hospitalizations. This suggests high one-dose varicella vaccine coverage can have a substantial impact on severe disease.

Duration of protection after first dose of acellular pertussis vaccine in infants

OBJECTIVE

Data on the effectiveness of the diphtheria-tetanus-acellular pertussis (DTaP) vaccine in the first 4 years of life are sparse. We evaluated the vaccine effectiveness (VE) of 1 and 2 doses of DTaP before 6 months of age and of 3 doses from 6 months of age in Australia, where, since 2003, a fourth dose is not given until 4 years.

METHODS

We matched reported pertussis cases aged 2 to 47 months between January 2005 and December 2009 to controls from a population-based immunization register by date of birth and region of residence. VE by number of doses and age group was calculated as (1 - odds ratio) × 100%.

RESULTS

VE against hospitalization increased from 55.3% (95% confidence interval [CI], 42.7%-65.1%) for 1 dose before 4 months of age to 83.0% (95% CI, 70.2%-90.3%) for 2 doses before 6 months. The VE of 3 doses of DTaP against all reported pertussis was 83.5% (95% CI, 79.1%-87.8%) between 6 and 11 months, declining to 70.7% (95% CI, 64.5%-75.8%) between 2 and 3 years of age and 59.2% (95% CI, 51.0%-66.0%) between 3 and 4 years of age.

CONCLUSIONS

DTaP provided good protection against pertussis in the first year of life from the first dose. Without a booster dose, the effectiveness of 3 doses waned more rapidly from 2 to 4 years of age than previously documented for children >6 years of age who had received 5 doses.

Intussusception risk and disease prevention associated with rotavirus vaccines in Australia's National Immunization Program

BACKGROUND

Estimates of the risk of intussusception (IS) associated with currently licensed rotavirus vaccines (RV1 [Rotarix; GSK] and RV5 [RotaTeq; Merck]) diverge. Contemporaneous introduction of both vaccines in Australia enabled a population-based assessment of risk.

METHODS

Confirmed cases of IS in infants aged 1 to <12 months were identified from national hospitalization databases, supplemented by active hospital-based surveillance, from July 2007 through June 2010. Vaccination histories were verified by the Australian Childhood Immunisation Register, which was also used to identify age-matched controls. Self-controlled case series and case-control methods were used to assess the risk of IS associated with both vaccines in prespecified periods after vaccination. The estimated burden of vaccine-attributable IS was compared with estimated reductions in gastroenteritis hospitalizations.

RESULTS

Based on 306 confirmed cases of IS, the relative incidence of IS in the 1-7-day period after the first vaccine dose, was 6.8 (95% confidence interval, 2.4-19.0; P < .001) for RV1, and 9.9 (95% confidence interval, 3.7-26.4; P < .001) for RV5. There was a smaller increased risk 1-7 days after the second dose of each vaccine. The case-control analysis gave similar results. We estimate an excess of 14 IS cases and >6500 fewer gastroenteritis hospitalizations in young children annually in Australia after vaccine introduction.

CONCLUSIONS

We found a similarly increased risk of IS after both vaccines, but the balance of benefits and risks at population level was highly favorable, a finding likely to extend to other settings despite varying incidence of IS and potentially higher morbidity and mortality from both gastroenteritis and IS.

Disseminated tuberculosis and tuberculous meningitis in Australian-born children; case reports and review of current epidemiology and management

We present two cases of tuberculous meningitis in Australian-born children. We review the current literature surrounding management of paediatric tuberculosis and disseminated disease, emphasising the importance of prompt diagnosis and intervention. We discuss the epidemiology of tuberculosis in the Australian paediatric population and highlight the sentinel role of childhood infection in public health surveillance.

Sources of pertussis infection in young infants: a review of key evidence informing targeting of the cocoon strategy

BACKGROUND

The relative contribution of different categories of contact in transmitting pertussis to very young infants, who experience the most severe morbidity, is the most important single factor determining the likely benefit of pertussis vaccination of their close contacts (the "cocooning" strategy).

OBJECTIVE

To identify, evaluate the quality of and summarise existing data on potential sources of infant pertussis infection in high income countries, focussing on infants under 6 months old.

DATA SOURCES

Online databases MEDLINE and EMBASE. Additional studies were identified from the reference lists of relevant articles. Study selection and analysis: Study quality was evaluated by standardised criteria, based on the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Pooled estimates of the proportion of pertussis cases attributable to various contact sources were calculated using data from the highest quality studies.

RESULTS

Nine studies met the inclusion criteria; seven included data on contacts of hospitalised infants less than 6 months old. Case definitions and methods of contact ascertainment were variable. Most identified sources were from the household, of which 39% (95%CI 33-45%) were mothers, 16% (95%CI 12-21%) fathers, and 5% (95%CI 2-10%) grandparents. Estimates for siblings (16-43%) and non-household contacts (4-22%) were more heterogeneous. For 32-52% of infant cases, no source was identified. Asymptomatic pertussis infection was found in 8-13% of contacts evaluated.

CONCLUSIONS

These data suggest that the greatest potential impact of pertussis vaccination of adults to prevent severe disease in young infants comes from vaccinating mothers, followed by fathers, with grandparents having a minor role. Siblings varied in importance and, given recent data regarding waning immunity in vaccinated children, need further study. Non-household sources are also well documented, highlighting the potential limitations of the cocoon strategy to prevent severe infant disease.

Decline in rotavirus hospitalisations following introduction of Australia's national rotavirus immunisation programme

AIM

To determine the impact of rotavirus immunisation on rotavirus hospitalisations in young children. methods: Annual hospitalisations for rotavirus gastroenteritis to The Children's Hospital at Westmead, a tertiary care paediatric hospital in Sydney, were recorded from 2001 for 6 years prior to and 2.5 years following the introduction of rotavirus vaccines to the National Immunisation Program. Data on hospital-acquired rotavirus gastroenteritis were collected prospectively.

RESULTS

Hospitalisations for rotavirus gastroenteritis declined in the two full rotavirus seasons (2008 and 2009) after vaccine introduction by 75% compared with mean annual hospitalisations from 2001 to 2006. The greatest decline was seen in those <12 months of age (93%), but the reduction occurred consistently across all age groups, even in children not eligible for immunisation, suggesting an effect on herd immunity. A substantial decline in nosocomial rotavirus gastroenteritis was seen from 2007 to 2009, suggesting a reduction in virus transmission in the hospital setting.

CONCLUSION

This study demonstrates a substantial reduction in hospitalisations in children of all ages to a large paediatric hospital and reduced nosocomial infections since the introduction of a nationally funded rotavirus immunisation programme in Australia.

Reduction in rotavirus-associated acute gastroenteritis following introduction of rotavirus vaccine into Australia's National Childhood vaccine schedule

INTRODUCTION

: Rotavirus vaccines were introduced into the funded Australian National Immunization Program (NIP) in July 2007. Due to purchasing arrangements, individual states and territories chose either a 2-dose RV1 (Rotarix, GSK) regimen or 3-dose RV5 (Rotateq, Merck/CSL) regimen. This allowed comparison of both vaccines in similar populations with high infant vaccination coverage.

METHODS

: Admission and rotavirus identification data from the major pediatric hospitals in 3 states (2 using RV5, 1 RV1), together with state-based hospitalization and vaccination data from Queensland (RV5) were analyzed for the years before, and up to 30 months following rotavirus vaccine introduction. Emergency encounters and short-stay unit admissions for gastroenteritis are also described.

RESULTS

: Rotavirus vaccine coverage in Australia is high, with 87% of infants receiving at least 1 dose. Hospital admissions for both rotavirus gastroenteritis and nonrotavirus-coded gastroenteritis were reduced following vaccine introduction in all states, not only for the age group eligible for NIP rotavirus vaccination, but also for children born prior. RV5 vaccine efficacy in Queensland has been estimated at 89.3%. Marked reductions in acute gastroenteritis emergency presentations and short-stay unit admissions have also been observed.

CONCLUSIONS

: Early evidence from the NIP in Australia has demonstrated high rotavirus coverage with both RV1 and RV5. The introduction of both vaccines has been associated with a marked reduction in gastroenteritis admissions, supportive of both direct vaccine protection, as well as with indirect herd protection.