Vaccination In Australia Research Articles

Playing with fire – What is influencing horse owners’ decisions to not vaccinate their horses against deadly Hendra virus infection?

Hendra virus is a zoonotic paramyxovirus, which causes severe respiratory and neurological disease in horses and humans. Since 2012, the Hendra virus sub-unit G vaccine has been available for horse vaccination in Australia. Uptake of the vaccine has been limited and spill-over events of Hendra virus infection in horses continue to occur. We conducted an online, questionnaire-based cross-sectional study of 376 horse owners belonging to a variety of different equestrian clubs in Queensland, Australia, to identify risk factors for non-vaccination against Hendra virus. A total of 43.1% (N = 162) of horse owners indicated that they currently did not vaccinate against Hendra virus infection, while 56.9% (N = 214) currently vaccinated against Hendra virus infection. A total of 52 risk factors were evaluated relating to equestrian activities, horse management, perceived risk and severity of horse and human infection with Hendra virus, side effects of Hendra vaccination, other vaccinations conducted by horse owners and horse owners’ attitudes towards veterinarians. The final multivariable logistics regression model identified the following risk factors associated with increased odds of non-vaccination against Hendra virus: 1) perceived low risk (compared to high) of Hendra virus infection to horses (considering the horse owners’ location and management practices) or horse owners were unsure about the risk of infection, 2) perceived moderate severity (compared to very severe or severe) of Hendra virus infection in humans, 3) horse owners non-vaccination of their pets, 4) horse owners non-vaccination against strangles disease in horses, 5) handling of more than three horses per week (compared to one horse only) and 6) perceived attitude that veterinarians had a high motivation of making money from Hendra virus vaccination (compared to veterinarians having a low motivation of making money from Hendra virus vaccination). Horse owners were more likely to vaccinate against Hendra virus if horses were used for dressage, show jumping or eventing. The study also identified horse owners’ concerns about side-effects and about the lack of evidence on vaccine efficacy.

Population-based estimates of the effectiveness of pneumococcal vaccination in Australia.

ABSTRACTObjectivesAustralia’s Childhood Immunisation Register (ACIR) is one of only a handful of national immunisation registers world-wide. We have, for the first time, linked the ACIR to other health datasets to measure the real-world impact of Australia’s immunisation program. In this study, we aimed to assess the population-based effectiveness of the 3-dose infant pneumococcal vaccination program (due at 2, 4, and 6 months) against invasive pneumococcal disease caused by the 7 vaccine specific serotypes. The 7-valent pneumococcal conjugate vaccine (PCV7) has been available since 2001 and a funded universal program started in 2005 (with a switch to 13-valent PCV in 2011). ApproachVaccination records from ACIR, death records, and invasive pneumococcal disease notifications for 2001-2013 were individually linked for 1.37 million children born in 2001-2012 in two Australian states (Western Australia and New South Wales). A Cox proportional hazards model (adjusting for sex, Indigenous status and year of birth) was used to estimate the hazard ratio for invasive pneumococcal disease in vaccinated compared to unvaccinated children less than 2 years old. The per cent of disease prevented by vaccination, or vaccine effectiveness, was calculated as (1-adjusted hazard ratio) x 100%. ResultsFrom 2005, vaccination coverage with dose 3 of the pneumococcal vaccine was steady at ~91% in eligible cohorts. Between 2001 and 2013, there were 468 notifications of invasive pneumococcal disease caused by the 7 vaccine specific serotypes during 2.66 million person years of observation; only 39 (8.3%) of these cases occurred after the universal program was implemented. Vaccine effectiveness against invasive pneumococcal disease caused by the 7 vaccine specific serotypes for 1, 2 and 3 doses of the pneumococcal vaccine was 68% (95%CI: 44-89%), 93% (81-97%), and 92% (95%CI: 86-93%), respectively. ConclusionThis is the first study to link Australia’s national immunisation register and measure population-based vaccine effectiveness. The study provides robust evidence of the effectiveness of at least 2 doses of pneumococcal vaccine against vaccine serotype specific infection using a 3 dose infant schedule.

Cost-effectiveness of the next generation nonavalent human papillomavirus vaccine in the context of primary human papillomavirus screening in Australia: a comparative modelling analysis

First generation bivalent and quadrivalent human papillomavirus (HPV) vaccines have been introduced in most developed countries. A next generation nonavalent vaccine (HPV9) has become available, just as many countries are considering transitioning from cytology-based to HPV-based cervical screening. A key driver for the cost-effectiveness of HPV9 will be a reduction in screen-detected abnormalities and surveillance tests. We aimed to evaluate the cost-effectiveness of HPV9 in Australia, a country with HPV vaccination of both sexes that is transitioning to 5-yearly HPV-based screening. We used Policy1-Cervix and HPV-ADVISE-two dynamic models of HPV transmission, vaccination, and cervical screening-to estimate the cost-effectiveness of HPV9 versus quadrivalent vaccine (HPV4), assuming lifelong vaccine protection, two vaccine doses, and that additional costs were incurred in girls only. Policy1-Cervix was used to estimate the lifetime risk of cervical cancer diagnosis and death. Probabilistic sensitivity analysis of the cost-effectiveness outcomes was done with both models, and results are presented as the median and 10th to 90th percentiles of simulation runs (referred to as 80% uncertainty intervals [UIs]). Compared with cytology-based screening, HPV screening is predicted to reduce lifetime risk of cervical cancer diagnosis by 18% and of death by 20%, even in unvaccinated cohorts. Under base-case assumptions (lifelong protection, full efficacy at two doses), HPV4 will provide a further reduction in diagnosis of 54% and in death of 53% and HPV9 will provide a further reduction in both diagnosis and death of 11%, compared with cytology-based screening in unvaccinated cohorts. For HPV9 to remain a cost-effective alternative to HPV4, the incremental cost per dose in girls should not exceed a median of AUS$35·99 (80% UI 28·47-41·18) with Policy1-Cervix or AUS$22·74 (15·49-34·45) with HPV-ADVISE, at a willingness-to-pay threshold of AUS$30 000 per quality-adjusted life-year. Differing methods and assumptions led to some differences in the estimates produced by the two models. However, on the basis of median results, HPV9 will be a cost-effective alternative to HPV4 if the additional cost per dose is AUS$23-36 (US$18-28). These results will be important when determining the optimum price of the vaccine in Australia. National Health and Medical Research Council, Australia.

Effectiveness of seasonal influenza vaccine in Australia, 2015: An epidemiological, antigenic and phylogenetic assessment

BackgroundA record number of laboratory-confirmed influenza cases were notified in Australia in 2015, during which type A(H3) and type B Victoria and Yamagata lineages co-circulated. We estimated effectiveness of the 2015 inactivated seasonal influenza vaccine against specific virus lineages and clades. MethodsThree sentinel general practitioner networks conduct surveillance for laboratory-confirmed influenza amongst patients presenting with influenza-like illness in Australia. Data from the networks were pooled to estimate vaccine effectiveness (VE) for seasonal trivalent influenza vaccine in Australia in 2015 using the case test-negative study design. ResultsThere were 2443 eligible patients included in the study, of which 857 (35%) were influenza-positive. Thirty-three and 19% of controls and cases respectively were reported as vaccinated. Adjusted VE against all influenza was 54% (95% CI: 42, 63). Antigenic characterisation data suggested good match between vaccine and circulating strains of A(H3); however VE for A(H3) was low at 44% (95% CI: 21, 60). Phylogenetic analysis indicated most circulating viruses were from clade 3C.2a, rather than the clade included in the vaccine (3C.3a). VE point estimates were higher against B/Yamagata lineage influenza (71%; 95% CI: 57, 80) than B/Victoria (42%, 95% CI: 13, 61), and in younger people. ConclusionsOverall seasonal vaccine was protective against influenza infection in Australia in 2015. Higher VE against the B/Yamagata lineage included in the trivalent vaccine suggests that more widespread use of quadrivalent vaccine could have improved overall effectiveness of influenza vaccine. Genetic characterisation suggested lower VE against A(H3) influenza was due to clade mismatch of vaccine and circulating viruses.

WHO SPEAKS FOR "WE" SPEAKS NOT FOR "ME" - THE VACCINATION DEBATE

Vaccinations are widely regarded as one of the great modern medical advances having saved many lives, and many more from disabilities. However, the success of vaccinations has led to a conflict between the utilitarian ethics of the common good versus the deontological ethics of individual rights. Growing vaccine hesitancy and policies designed to force non-vaccinators to vaccinate inflame the debate. The key question examined is whether, in the case of vaccination, there is justification for limiting individual rights to choose as in Australia's "no jab no pay" policy which removes the possibility of conscientious objection. Examined in this way, it is concluded that it probably matters little whether non-vaccinators vaccinate or not. Because of the success of mass vaccination in Australia, the risks of infection and consequent morbidity/mortality are low - as are the risks of an adverse vaccination reaction. Having non-vaccinators vaccinate is likely to provide little gain, herd immunity levels will change very little. The debate distracts efforts from more promising unvaccinated target groups (those lacking access), and more generally, from other more useful public goods. It is concluded that promoting vaccination for the common good is to be encouraged, and so is the option allowing an individual to conscientiously object.

PT274 The Economic Case for a Group A Streptococcal Vaccine in Australia and New Zealand

PT274 The Economic Case for a Group A Streptococcal Vaccine in Australia and New Zealand

Willingness to pay for MenB vaccine in Australia

Willingness to pay for MenB vaccine in Australia

Retrospective economic evaluation of childhood 7-valent pneumococcal conjugate vaccination in Australia: Uncertain herd impact on pneumonia critical

BackgroundRetrospective cost-effectiveness analyses of vaccination programs using routinely collected post-implementation data are sparse by comparison with pre-program analyses. We performed a retrospective economic evaluation of the childhood 7-valent pneumococcal conjugate vaccine (PCV7) program in Australia. MethodsWe developed a deterministic multi-compartment model that describes health states related to invasive and non-invasive pneumococcal disease. Costs (Australian dollars, A$) and health effects (quality-adjusted life years, QALYs) were attached to model states. The perspective for costs was that of the healthcare system and government. Where possible, we used observed changes in the disease rates from national surveillance and healthcare databases to estimate the impact of the PCV7 program (2005–2010). We stratified our cost-effectiveness results into alternative scenarios which differed by the outcome states included. Parameter uncertainty was explored using probabilistic sensitivity analysis. ResultsThe PCV7 program was estimated to have prevented ∼5900 hospitalisations and ∼160 deaths from invasive pneumococcal disease (IPD). Approximately half of these were prevented in adults via herd protection. The incremental cost-effectiveness ratio was ∼A$161,000 per QALY gained when including only IPD-related outcomes. The cost-effectiveness of PCV7 remained in the range A$88,000–$122,000 when changes in various non-invasive disease states were included. The inclusion of observed changes in adult non-invasive pneumonia deaths substantially improved cost-effectiveness (∼A$9000 per QALY gained). ConclusionUsing the initial vaccine price negotiated for Australia, the PCV7 program was unlikely to have been cost-effective (at conventional thresholds) unless observed reductions in non-invasive pneumonia deaths in the elderly are attributed to it. Further analyses are required to explore this finding, which has significant implications for the incremental benefit achievable by adult PCV programs.

O16.1 The rapid and near elimination of human papillomavirus (hpv) type 6, 11, 16 and 18 among young high-risk women within three years of the national hpv vaccination programme in australia: findings from a 10-year cross-sectional study

Introduction The national quadrivalent human papillomavirus (HPV) vaccination programme was launched in Australia in April 2007. The aim of this study was to explore the proportion of vaccine targeted HPV genotypes contained in the quadrivalent (4vHPV) and the nine-valent (9vHPV) vaccines detected among young women diagnosed with Chlamydia trachomatis . Methods Women ≤25 years attending Melbourne Sexual Health Centre from 1-July-2004 to 30-June-2014 and diagnosed with chlamydia were included in the analysis. Detection of HPV genotypes was performed on stored cervical or high vaginal samples. The proportions of women who had 4vHPV types (6/11/16/18) and the other five types within the 9vHPV grouping (31/33/45/52/58 alone) excluding 4vHPV types were calculated for each Australian financial year and stratified by age and vaccine eligibility. The proportions of HPV types among unvaccinated women in the post-vaccination period were also calculated to assess herd protection. Results A total of 1,202 women were included in this study. The proportion of samples with 4vHPV types dramatically decreased among Australian-born ≤25 year old females over the 10 year period (6/11 decreased from 16% to 2% [ p trend p trend p = 0 .031), but no decline was seen in the other five types within the 9vHPV grouping (22.5% vs. 25.9%; p = 0 .805). Conclusion Coverage achieved using the 3-dose vaccine was sufficient to largely eradicate 4vHPV types in Australian born women ≤21 years old, within three years of the introduction of the national HPV vaccination program. A strong herd protection was observed among women, with a significant decline in the proportion of 4vHPV in unvaccinated women. Disclosure of interest statement EPFC has received a conference sponsorship from CSL Biotherapies. CKF has received honoraria from CSL Biotherapies and Merck and research funding from CSL Biotherapies. CKF owns shares in CSL Biotherapies the manufacturer for Gardasil. SNT and SMG are investigators on a national prevalence study of cervical cancer tissue that is receiving unrestricted funding from bioCSL, supplier of HPV vaccine in Australia. SMG has received grant support from CSL and GlaxoSmithKline, and lecture fees from Merck, GSK and Sanofi Pasteur; in addition, she has received funding through her institution to conduct HPV vaccine studies for Merck Sharp and Dohme and GlaxoSmithKline. SMG is a member of the Merck Global Advisory Board and the Merck Scientific Advisory Committee for HPV. MYC has been an investigator on investigator initiated research grants from Merck Sharp and Dohme. MGL receives unrestricted grants from Boehringer Ingelhiem, Gilead Sciences, Merck Sharp and Dohme, Bristol-Myers Squibb, Janssen-Cilag, ViiV HealthCare. All other authors have no conflicts of interest.

Intussusception in Australia: epidemiology prior to the introduction of rotavirus vaccine

ObjectivesTo describe the incidence rate and clinical outcomes of intussusception in Australia in children aged <24 months prior to the use of rotavirus vaccines in Australia, and to explore associations between patient characteristics and outcomes in children with intussusception. MethodsThis study used Australian national hospital discharge data on intussusception from July 2000 to June 2006 for children aged <24 months and data from the Australian Bureau of Statistics (ABS) as a proxy for population numbers to estimate incidence. Logistic regression was used to examine associations between patient characteristics (age, sex, ethnicity) and outcomes (length of hospital stay >2 days and the need for surgical intervention). ResultsThe overall incidence rate of intussusception was 5.4 per 10,000 child‐years in children under 24 months (95%CI 5.17–5.70). There was a declining rate over the study period (p<0.001). Age at time of intussusception was strongly associated with length of hospital stay and surgery. ConclusionsThis study provides an estimate of the pre‐rotavirus vaccine incidence of intussusception across Australia, which is important for monitoring the occurrence of intussusceptions post the introduction of rotavirus vaccine.

Are we prepared for Ebola and other viral haemorrhagic fevers?

Are we prepared for Ebola and other viral haemorrhagic fevers?

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

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. 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. 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). 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.

Case for Pharmacist Administered Vaccinations in Australia

ABSTRACTBackgroundPharmacists in Portugal, New Zealand, the UK and USA are able to administer vaccines. Despite international trends, current jurisdictional regulations prevent Australian pharmacists from administering vaccines.AimTo assess if there is a case for pharmacist administered vaccination (PAV) in Australia.DiscussionStudies and government data indicate suboptimal uptake of some vaccines in Australia. Over the past two decades, PAV services have been introduced successfully in some developed countries. Available literature revealed PAVs provided significant benefits in these countries, such as increased vaccination uptake and subsequent decreased disease burden and associated cost benefits. PAVs are in line with Australian government policy and priorities. The pharmacy profession, guided by peak professional bodies, has demonstrated a willingness to embrace PAVs based on appropriate competencies and broadening health delivery options to the public.ConclusionThere is a case for PAV services in Australia. It is not possible to adopt an overseas model of PAVs in Australia without significant modification to its unique immunisation program, which incorporates a different funding and governance system.

Intussusception Risk and Disease Prevention Associated With Rotavirus Vaccines in Australia's National Immunization Program

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. 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. 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. 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.

Changes in Patterns of Hospitalized Children With Varicella and of Associated Varicella Genotypes After Introduction of Varicella Vaccine in Australia

Varicella in children, although usually mild, can cause hospitalization and rarely death. This study examined patterns of hospitalized children with varicella, and associated varicella genotypes, in 4 tertiary children's hospitals throughout Australia before and after varicella vaccine was introduced. We obtained coded data on discharge diagnoses from each hospital before (1999 to 2001) and after (2007 to 2010) varicella vaccine introduction in 2005, adding active surveillance to capture clinical features, complications and immunization history in the latter period. Varicella vesicles were swabbed, and genotyping of varicella strains was performed by real-time polymerase chain reaction amplification. Overall, a 68% reduction in coded hospitalizations (varicella, 73.2% [P < 0.001]; zoster, 40% [P = 0.002]) occurred post-vaccine introduction. Of children with detailed clinical data (97 varicella and 18 zoster cases), 46 (40%) were immunocompromised. Only 6 of 32 (19%) age-eligible immunocompetent children were immunized. Complications, most commonly secondary skin infections (n = 25) and neurologic conditions (n = 14), occurred in 44% of children. There were no deaths; but 3 immunocompetent unimmunized children had severe multiple complications requiring intensive care. All strains genotyped were "wild-type" varicella, with Clade 1 (European origin) predominating. After the introduction of varicella vaccine, coverage of greater than 80% at 2 years of age was achieved, with varicella hospitalizations reduced by almost 70%. Of hospitalized children age-eligible for varicella vaccine, 80% were unimmunized, including all cases requiring intensive care.

Confidence at the expense of trust: The mass adoption of the Human Papillomavirus (HPV) vaccine in Australia

Confidence at the expense of trust: The mass adoption of the Human Papillomavirus (HPV) vaccine in Australia

Confidence at the expense of trust: The mass adoption of the Human Papillomavirus vaccine in Australia

Australia leads the world in the mass adoption of Human Papillomavirus (HPV) vaccines, a new frontier in mass vaccination programmes. This article reports on participatory workshops with the first generation of young Australian women to participate in the HPV mass vaccination programme. In particular, it addresses the themes of trust and confidence. A substantial literature highlights the growing realm of active trust at the expense of habitual confidence in ‘risk society’. Another line of inquiry highlights the preference of governments for policies designed to enhance confidence rather than trust. This study finds that participants were guided by confidence in their adoption of the HPV vaccine, at the expense of trust. Participants readily transferred their confidence in the existing vaccination regime to the HPV mass vaccination programme, notwithstanding its novel features. Yet participants expressed growing misgivings about their informed consent and the ‘marketing’ of the vaccine in the course of workshops, reflecting failure to achieve their active trust.

Outbreak-specific monovalent/bivalent vaccination to control and eradicate virulent ovine footrot

Footrot is a contagious disease of small ruminants which is caused by the bacterium Dichelobacter nodosus. In its virulent form there are severe economic losses and a very significant animal welfare issue. Sheep and goats can be vaccinated for treatment and prevention of the disease. There are 10 different serogroups of D. nodosus (A–I and M) and immunity is serogroup-specific. When all 10 serogroups are presented together in a vaccine, protection persists for only a few months due to “antigenic competition”. Consequently we evaluated the use of sequential monovalent or bivalent vaccines to control/eliminate/eradicate virulent footrot in a longitudinal intervention study on 12 commercial farms in southeast Australia with flock sizes of approximately 1200–4200 sheep. Overall, virulent footrot was eradicated from 4 of the flocks, 2 of which had 2 serogroups, and the others 4 or 5 serogroups. Where there were only 1 or 2 serogroups (3 farms) the clinical response was rapid and dramatic; prevalence was reduced from 45 to 50% before vaccination to 0% (2 farms) or 0.4% (1 farm) after one round of vaccination. In the remaining 9 flocks there were more than 2 serogroups and successive bivalent vaccines were administered leading to eradication of virulent footrot on 2 farms over 4 years and control of the disease on all but 3 of the others. Of the latter farms, 1 discontinued, and 2 initially had poor response to vaccine due to misdiagnosis of serogroup ‘M’, which was previously unknown in Australia. Control was achieved after administration of a serogroup M vaccine. These results provide clear evidence for control, elimination and eradication of virulent footrot by outbreak-specific vaccination in Australia.

Impact of rotavirus vaccination in Australia

Rotavirus is the major cause of gastroenteritis in young children worldwide, resulting in >500 000 deaths annually. In an effort to reduce the disease burden two live oral rotavirus vaccines were developed: Rotarix a monovalent vaccine and RotaTeq a pentavalent vaccine containing five human-bovine reassortant strains. Both vaccines were introduced into the Australian National Immunisation Program in July 2007. Each state and territory health agency has independently selected the rotavirus vaccine to include in its immunisation schedule. Studies from multiple Australian states have shown that emergency room visits and hospitalisation for rotavirus have declined dramatically since vaccine introduction. Studies have been conducted comparing the impact of the different vaccines on the circulating rotavirus strains. Differences in the prevalence of genotypes G2P[4] and G3P[8] were identified between states, while rare genotypes have recently been identified as a minor cause of disease in Australian children. Vaccine introduction has resulted in a dramatic decline in the rates of severe rotavirus disease. Since vaccine introduction, changes have been demonstrated in circulating strains. This likely reflects the natural annual fluctuations in strain prevalence rather than a lack of vaccine protection. Additional studies are required to determine the longer-term impact of vaccine introduction on circulating strains.

Estimating rotavirus gastroenteritis hospitalisations by using hospital episode statistics before and after the introduction of rotavirus vaccine in Australia

IntroductionHospital discharge records and laboratory data have shown a substantial early impact from the rotavirus vaccination program that commenced in 2007 in Australia. However, these assessments are affected by the validity and reliability of hospital discharge coding and stool testing to measure the true incidence of hospitalised disease. The aim of this study was to assess the validity of these data sources for disease estimation, both before and after, vaccine introduction. MethodsAll hospitalisations at a major paediatric centre in children aged <5 years from 2000 to 2009 containing acute gastroenteritis (AGE) ICD 10 AM diagnosis codes were linked to hospital laboratory stool testing data. The validity of the rotavirus-specific diagnosis code (A08.0) and the incidence of hospitalisations attributable to rotavirus by both direct estimation and with adjustments for non-testing and miscoding were calculated for pre- and post-vaccination periods. ResultsA laboratory record of stool testing was available for 36% of all AGE hospitalisations (n=4948) the rotavirus code had high specificity (98.4%; 95% CI, 97.5–99.1%) and positive predictive value (96.8%; 94.8–98.3%), and modest sensitivity (61.6%; 58–65.1%). Of all rotavirus test positive hospitalisations only a third had a rotavirus code. The estimated annual average number of rotavirus hospitalisations, following adjustment for non-testing and miscoding was 5- and 6-fold higher than identified, respectively, from testing and coding alone. Direct and adjusted estimates yielded similar percentage reductions in annual average rotavirus hospitalisations of over 65%. ConclusionDue to the limited use of stool testing and poor sensitivity of the rotavirus-specific diagnosis code routine hospital discharge and laboratory data substantially underestimate the true incidence of rotavirus hospitalisations and absolute vaccine impact. However, this data can still be used to monitor vaccine impact as the effects of miscoding and under-testing appear to be comparable between pre and post vaccination periods.