C. Raina MacIntyre

Compulsory vaccination and conscientious or philosophical exemptions: Past, present, and future

Compulsory vaccination has contributed to the success of immunisation programmes in the USA and Australia, yet the benefits from compulsory vaccination are not universally recognised. Some people--experts and the public alike--believe that the benefits of compulsory vaccination are outweighed by the associated ethical problems. A review of vaccination legislation in the UK, Australia, and the USA raises four main points. First, compulsory vaccination may be effective in preventing disease outbreaks, reaching and sustaining high immunisation coverage rates, and expediting the introduction of new vaccines. Second, to be effective, compulsory programmes must have a reliable supply of safe and effective vaccines and most people must be willing to be vaccinated. Third, allowance of exemptions to compulsory vaccination may limit public backlash. Finally, compulsory vaccination may increase the burden on governments to ensure the safety of vaccines. Nevertheless, although compulsory immunisation can be very effective, it might not be acceptable in some countries where high coverage has been achieved through other approaches or efforts, such as in Sweden, Norway, Denmark, the Netherlands, and the UK. These factors should be considered when compulsory vaccinations are being introduced or immunisation laws refined. Lessons learned from compulsory vaccination could be useful to other public-health programmes.

Cost-effectiveness analyses of human papillomavirus vaccination

With a human papillomavirus (HPV) vaccine soon to become available for widespread use, several studies have modelled the cost-effectiveness of vaccination. These pioneer studies are likely to be influential on the design of further analyses, and we have therefore summarised and critically reviewed the strengths and limitations of their methods and assumptions. Despite a lack of transparency in some key elements, the most influential assumptions were identified as relating to vaccine effectiveness, cervical screening, and model design. Although the studies suggest that the introduction of an HPV vaccine could be cost effective compared with current practice in the USA, there is still substantial uncertainty around key variables, and model validation seems insufficient. The desirability of vaccinating boys in addition to girls has been explored in only one study. Further refinements to model design and epidemiological variables of (type-specific) HPV disease progression, and expansions on the options for vaccine use, are required for policy making.

Accuracy of ICD–9–CM codes in hospital morbidity data, Victoria: implications for public health research

Abstract: Hospital morbidity data in the form of International classification of diseases, 9th revision, clinical modification codes are often used for epidemiological studies and disease surveillance. We aimed to evaluate the reliability of the Victorian In–patient Minimum Database for use in epidemiological studies and disease surveillance. Data from 1993–94 were collected, as part of a coding audit of public hospitals in Victoria, from 7052 randomly selected records. The frequency of discrepancy in any coding field was 53 per cent, and of discrepancy in the principal diagnosis, 22 per cent. New Australian national diagnosis–related group (ANDRG) codes were assigned as a result of discrepancy in 13.6 per cent of cases. Discrepancy rates increased with increasing rarity of ANDRG, from 50 per cent to 56 per cent. Predictors of change in ANDRG assignment were discrepancy in the principal diagnosis, ANDRG frequency of over 0.6 per cent, more than three diagnoses, medical ANDRGs, length of stay over five days and rural hospitals. Rates of any discrepancy increased from 36 per cent in patients with one diagnosis to 94 per cent in patients with 12 diagnoses. The discrepancy rates were consistent with those of other studies. Coding discrepancy is likely to be caused by universal difficulties associated with the coding of hospital records, rather than any unique local problems. The predictors of discrepancy suggest that more complex cases are more prone to coding discrepancy. In areas where the database is less reliable, use of a supplementary data source, such as linkage studies, would improve reliability. (Aust N Z J Public Health 1997; 21: 477–82)

Funding of drugs: do vaccines warrant a different approach?

Summary Vaccines have features that require special consideration when assessing their cost-effectiveness. These features are related to herd immunity, quality-of-life losses in young children, parental care and work loss, time preference, uncertainty, eradication, macroeconomics, and tiered pricing. Advisory committees on public funding for vaccines, or for pharmaceuticals in general, should be knowledgable about these special features. We discuss key issues and difficulties in decision making for vaccines against rotavirus, human papillomavirus, varicella-zoster virus, influenza virus, and Streptococcus pneumoniae. We argue that guidelines for economic evaluation should be reconsidered generally to recommend (1) modelling options for the assessment of interventions against infectious diseases; (2) a wider perspective to account for impacts on third parties, if relevant; (3) a wider scope of costs than health-care system costs alone, if appropriate; and (4) alternative discounting techniques to explore social time preference over long periods.

Herpes zoster burden of illness and health care resource utilisation in the Australian population aged 50 years and older

Incidence of zoster and post-herpetic neuralgia (PHN) and associated health care resource utilisation were investigated in the Australian population aged > or =50 years, using general practice data from 2000 to 2006, and pharmaceutical prescribing, hospital morbidity and emergency department data from 1998 to 2005. Zoster and PHN incidence rates were estimated as approximately 10/1000 and 1.45/1000 persons, respectively, with antivirals prescribed for 73.5% of zoster cases. Estimated hospitalisation and emergency department visit rates were 0.67/1000 and 0.38/1000 persons, respectively. Management of zoster (including PHN) involved approximately 2.4 general practitioner consultations. Total costs to the health care system were estimated as approximately 32.8 million per year. The substantial burden of zoster and PHN highlights the potential benefit of zoster vaccination.

Population Seroprevalence of Human Papillomavirus Types 6, 11, 16, and 18 in Men, Women, and Children in Australia

BACKGROUND Representative population-based data on human papillomavirus (HPV) epidemiology are important for public health decision making but are difficult to obtain. Seroepidemiology is a valuable tool, although the relationship between HPV infection and seropositivity is incomplete. METHODS We obtained a large representative sample using residual diagnostic test serum samples obtained from individuals aged 0-69 years (1247 samples from male patients and 1523 samples from female patients) in Australia. Serum antibody levels to HPV types 6, 11, 16, and 18 were measured using an immunoassay. RESULTS Overall, seroprevalence of HPV types 6 and 16 was higher than seroprevalence of HPV types 11 and 18. Among female patients, peak HPV seropositivity occurred among those who were 30-39 years of age for types 6, 16, and 18 (22%, 22%, and 10.5%, respectively) and among those who were 40-49 years of age for HPV 11 (11.8%). Among male subjects, peak HPV seropositivity occurred among those who were 40-49 years of age for types 6 and 11 (15.4% and 9.1%, respectively) and among those who were 50-59 years of age for types 16 and 18 (14.3% and 8.2%, respectively). No cases of HPV seropositivity were detected in individuals <10 years of age. CONCLUSIONS Australian seroepidemiological data, showing differing age-specific patterns of HPV seropositivity in male and female patients, are likely to be generalizable to other developed countries and add to other data supporting completion of HPV vaccination before adolescence.

National serosurvey of cytomegalovirus in Australia

ABSTRACT In anticipation of the development of a vaccine against cytomegalovirus (CMV), we conducted a large, nationally representative serosurvey to examine the seroprevalence of CMV in Australia. Sera were collected opportunistically from laboratories around Australia. Age- and gender-representative samples were tested for CMV antibody. The population-weighted rate of CMV seropositivity in subjects between 1 and 59 years of age was 57% (95% confidence interval, 55.2 to 58.6%). An association between CMV seroprevalence and increasing age was recognized; however, little overall difference in seroprevalence between the sexes was found. The finding that high levels of CMV exposure occur in the first few years of life suggests that for a universal vaccination program to have maximal impact, the vaccine would need to be delivered to infants and have a long duration of protective efficacy. This is the first national serosurvey looking at cytomegalovirus in the Australian community. This study provides valuable information that can be used to examine the incidence of infection in the community and help focus the administration of a future CMV vaccine to appropriate target populations.

Influenza-related hospitalisation and death in Australians aged 50 years and older

Summary Estimating the true burden of influenza is problematic because relatively few hospitalisations or deaths are specifically coded as influenza related. Statistical regression techniques using influenza and respiratory syncytial virus surveillance data were used to estimate the number of excess hospitalisations and deaths attributable to influenza. Several International Classification of Diseases 10th Revision (ICD-10) groupings were used for both hospitalisation and mortality estimates, including influenza and pneumonia, other respiratory disorders, and circulatory disorders. For Australians aged 50–64 years, the annual excess hospitalisations attributable to influenza were 33.3 (95%CI: 23.2–43.4) per 100,000 for influenza and pneumonia and 57.6 (95%CI: 32.5–82.8) per 100,000 for other respiratory disorders. For Australians aged ≥65 years, the annual excess hospitalisations attributable to influenza were 157.4 (95%CI: 108.4–206.5) per 100,000 for influenza and pneumonia and 282.0 (95%CI: 183.7–380.3) per 100,000 for other respiratory disorders. The annual excess all-cause mortality attributable to influenza was 6.4 (95%CI: 2.6–10.2) per 100,000 and 116.4 (95%CI: 71.3–161.5) per 100,000, for Australians aged 50–64 years and those aged ≥65 years, respectively. In the age-group ≥65 years, a significant association was found between influenza activity and circulatory mortality. We conclude that influenza is responsible for a substantial amount of mortality and morbidity, over and above that which is directly diagnosed as influenza in Australians aged ≥50 years.

Will they just pack up and leave? – attitudes and intended behaviour of hospital health care workers during an influenza pandemic

BackgroundThere is a general consensus that another influenza pandemic is inevitable. Although health care workers (HCWs) are essential to the health system response, there are few studies exploring HCW attitudes to pandemic influenza. The aim of this study was to explore HCWs knowledge, attitudes and intended behaviour towards pandemic influenza.MethodsCross-sectional investigation of a convenience sample of clinical and non-clinical HCWs from two tertiary-referral teaching hospitals in Sydney, Australia was conducted between June 4 and October 19, 2007. The self-administered questionnaire was distributed to hospital personal from 40 different wards and departments. The main outcome measures were intentions regarding work attendance and quarantine, antiviral use and perceived preparation.ResultsRespondents were categorized into four main groups by occupation: Nursing (47.5%), Medical (26.0%), Allied (15.3%) and Ancillary (11.2%). Our study found that most HCWs perceived pandemic influenza to be very serious (80.9%, n = 873) but less than half were able to correctly define it (43.9%, n = 473). Only 24.8% of respondents believed their department to be prepared for a pandemic, but nonetheless most were willing to work during a pandemic if a patient or colleague had influenza. The main determinants of variation in our study were occupational factors, demographics and health beliefs. Non-clinical staff were significantly most likely to be unsure of their intentions (OR 1.43, p < 0.001). Only 42.5% (n = 459) of respondents considered that neuraminidase inhibitor antiviral medications (oseltamivir/zanamivir) would protect them against pandemic influenza, whereas 77.5% (n = 836) believed that vaccination would be of benefit.ConclusionWe identified two issues that could undermine the best of pandemic plans – the first, a low level of confidence in antivirals as an effective measure; secondly, that non-clinical workers are an overlooked group whose lack of knowledge and awareness could undermine pandemic plans. Other issues included a high level of confidence in dietary measures to protect against influenza, and a belief among ancillary workers that antibiotics would be protective. All health care worker strategies should include non clinical and ancillary staff to ensure adequate business continuity for hospitals. HCW education, psychosocial support and staff communication could improve knowledge of appropriate pandemic interventions and confidence in antivirals.

Acute myocardial infarction and influenza: a meta-analysis of case–control studies

Objective Acute myocardial infarction (AMI) is the leading cause of death and disability globally. There is increasing evidence from observational studies that influenza infection is associated with AMI. In patients with known coronary disease, influenza vaccination is associated with a lower risk of cardiovascular events. However, the effect of influenza vaccination on incident AMI across the entire population is less well established. Method The purpose of our systematic review of case–control studies is twofold: (1) to estimate the association between influenza infection and AMI and (2) to estimate the association between influenza vaccination and AMI. Cases included those conducted with first-time AMI or any AMI cases. Studies were appraised for quality and meta-analyses using random effects models for the influenza exposures of infection, and vaccination were conducted. Results 16 studies (8 on influenza vaccination, 10 on influenza infection and AMI) met the eligibility criteria, and were included in the review and meta-analysis. Recent influenza infection, influenza-like illness or respiratory tract infection was significantly more likely in AMI cases, with a pooled OR 2.01 (95% CI 1.47 to 2.76). Influenza vaccination was significantly associated with AMI, with a pooled OR of 0.71 (95% CI 0.56 to 0.91), equating to an estimated vaccine effectiveness of 29% (95% CI 9% to 44%) against AMI. Conclusions Our meta-analysis of case–control studies found a significant association between recent respiratory infection and AMI. The estimated vaccine effectiveness against AMI was comparable with the efficacy of currently accepted therapies for secondary prevention of AMI from clinical trial data. A large-scale randomised controlled trial is needed to provide robust evidence of the protective effect of influenza vaccination on AMI, including as primary prevention.