Heterogeneity in influenza seasonality and vaccine effectiveness in Australia, Chile, New Zealand and South Africa: early estimates of the 2019 influenza season.

We compared 2019 influenza seasonality and vaccine effectiveness (VE) in four southern hemisphere countries: Australia, Chile, New Zealand and South Africa. Influenza seasons differed in timing, duration, intensity and predominant circulating viruses. VE estimates were also heterogeneous, with all-ages point estimates ranging from 7-70% (I2: 33%) for A(H1N1)pdm09, 4-57% (I2: 49%) for A(H3N2) and 29-66% (I2: 0%) for B. Caution should be applied when attempting to use southern hemisphere data to predict the northern hemisphere influenza season.

Hepatocellular carcinoma over three decades in Victoria, Australia: epidemiology, diagnosis and trends, 1984-2013.

BACKGROUND: Liver cancer continues to be a health priority in Australia, with the majority attributable to preventable causes, and certain populations at higher risk. AIMS: Epidemiological assessment of incidence, trends and distribution to inform prevention, and reassessment of data in light of recent changes to registry case definitions. METHODS: Reported cases of hepatocellular carcinoma (HCC) in Victoria, Australia, 1984-2013, were obtained from the Victorian Cancer Registry. Demographic characteristics were examined, incidence and survival assessed using Poisson and Cox regression, and geographic distribution mapped. Incidence was compared before and after inclusion of non-histologically confirmed cases in Registry data to assess impacts on incidence trends. RESULTS: Diagnoses of HCC rose substantially between 1984 and 2013, increasing sixfold from 0.9 to 5.9 per 100 000. The rate of increase per year accelerated from 5.3% between 1984 and 2003 to 9.5% between 2004 and 2013. Cases were disproportionately male (80%), median age at diagnosis was 66 years and 53% were born overseas. Even during 2004-2013, 5-year survival was only 16%, although higher among younger people, metropolitan residents and people born overseas. Incidence showed strong geographic clustering. The proportion of cases diagnosed clinically increased from 1% during 1984-2004 to 43% in 2009-2013. The revised case definition added 993 cases (27.3% of total). CONCLUSION: Cases of HCC are becoming increasingly common, and revised incidence estimates highlight the impact of case definitions in the context of changing diagnostic approaches. The ongoing burden, disproportionate population distribution and low survival emphasise the importance of prevention and early detection as a public health imperative.

Low interim influenza vaccine effectiveness, Australia, 1 May to 24 September 2017.

In 2017, influenza seasonal activity was high in the southern hemisphere. We present interim influenza vaccine effectiveness (VE) estimates from Australia. Adjusted VE was low overall at 33% (95% confidence interval (CI): 17 to 46), 50% (95% CI: 8 to 74) for A(H1)pdm09, 10% (95% CI: -16 to 31) for A(H3) and 57% (95% CI: 41 to 69) for influenza B. For A(H3), VE was poorer for those vaccinated in the current and prior seasons.

Increase in Meningococcal Serogroup W Disease, Victoria, Australia, 2013-2015.

In Victoria, Australia, invasive meningococcal disease caused by Neisseria meningitidis serogroup W increased from 4% of all cases in 2013 to 30% in 2015. This increase resulted largely from strains similar to those in the serogroup W sequence type 11 clonal complex, previously described in the United Kingdom and South America.

Effectiveness of clindamycin and intravenous immunoglobulin, and risk of disease in contacts, in invasive group a streptococcal infections.

BACKGROUND: The use of clindamycin and intravenous immunoglobulin (IVIG) in treatment of invasive group A streptococcal (iGAS) infection, and the need for prophylactic antibiotics in close contacts, remains contentious. Controlled trials are unlikely to be conducted, so prospective, observational studies provide the best data to inform practice. METHODS: We conducted population-based, prospective, active surveillance of iGAS infections throughout the state of Victoria, Australia (population 4.9 million), from March 2002 through August 2004. RESULTS: Eighty-four cases of severe iGAS infection (streptococcal toxic shock syndrome, necrotizing fasciitis, septic shock, or GAS cellulitis with shock) were identified. Clindamycin-treated patients had more severe disease than clindamycin-untreated patients but lower mortality (15% vs 39%; odds ratio [OR], 0.28; 95% confidence interval [CI], .10-.80). Among those who received concurrent IVIG, the fatality rate was lower still (7%). The adjusted point estimate of the OR for mortality was lower in clindamycin-treated patients (0.31; 95% CI, .09-1.12) and clindamycin plus IVIG-treated patients (0.12; 95% CI, .01-1.29) compared with clindamycin-untreated patients. Three confirmed cases of iGAS infection occurred in household contacts of index cases. The incidence rate of iGAS disease in contacts was 2011 (95% CI, 413-5929) times higher than the population incidence in Victoria. CONCLUSIONS: Our data suggest that clindamycin treatment of patients with severe iGAS infections substantially reduces mortality and that this effect may be enhanced by concurrent treatment with IVIG. The dramatically increased risk of iGAS disease among household contacts within 1 month of the index case highlights a potential role for antibiotic prophylaxis.

Burden of antimicrobial prescribing in primary care attributable to sore throat: a retrospective cohort study of patient record data.

BACKGROUND: Reducing antibiotic use in Australia, and the subsequent impact on antimicrobial resistance, requires multiple, sustained approaches with appropriate resources and support. Additional strategies to reduce antibiotic prescribing include effective vaccines, against pathogens such as Streptococcus pyogenes, the most common bacterial cause of sore throat. As part of efforts towards assessing the benefits of introducing new strategies to reduce antimicrobial prescribing, we aimed to determine the burden of antimicrobial prescribing for sore throat in general practice. METHODS: General practice activity data from 2013 - 2017 derived from the first 8 practices participating in the 'Primary Care Audit, Teaching and Research Open Network' (Patron) program were analysed according to reason for visit (upper respiratory tract infection, URTI, or sore throat) and antibiotic prescription. The main outcome measures were percentage of sore throat or URTI presentations with antibiotic prescription by age. RESULTS: A total of 722,339 visits to general practice were made by 65,449 patients; 5.7% of visits were for URTI with 0.8% meeting the more specific criteria for sore throat. 66.1% of sore throat visits and 36.2% of URTI visits resulted in antibiotic prescription. Penicillin, the recommended antibiotic for sore throat when indicated, was the antibiotic of choice in only 52.9% of sore throat cases prescribed antibiotics. Broader spectrum antibiotics were prescribed more frequently in older age groups. CONCLUSIONS: Frequency of antibiotic prescribing for sore throat is high and broad, despite Australian Therapeutic guideline recommendations. Multiple, sustained interventions to reduce prescribing, including availability of effective S. pyogenes vaccines that could reduce the incidence of streptococcal pharyngitis, could obviate the need to prescribe antibiotics and support ongoing efforts to promote antimicrobial stewardship.

Differential COVID-19 case ascertainment by age and vaccination status in Victoria, Australia: a serosurveillance and record linkage study.

Objectives: To compare serological evidence of prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with linked coronavirus disease 2019 (COVID-19) case notification data in Victoria, Australia, and to determine in vitro SARS-CoV-2 neutralisation activity based on prior infection and vaccination history. Design, setting, participants: Four cross-sectional serological surveys were conducted between 30 June and 31 October 2022 (a period of Omicron BA.4/BA.5 dominance) using 1,974 residual serum samples obtained from the Victorian Infectious Diseases Reference Laboratory. Serological results were linked to COVID-19 case notification and vaccination data. Surrogate virus neutralisation testing was performed to obtain in vitro inhibition estimates by anti-nucleocapsid serostatus and COVID-19 vaccination history. Main outcome measures: Adjusted anti-SARS-CoV-2 spike and nucleocapsid seropositivity by sex, age and region of residence; adjusted proportion of cases notified by anti-nucleocapsid serostatus, age and number of COVID-19 vaccination doses received; adjusted percentage in vitro inhibition against wildtype and Omicron BA.4/BA.5 SARS-CoV-2 variants by anti-nucleocapsid serostatus and COVID-19 vaccination history. Results: The prevalence of anti-SARS-CoV-2 nucleocapsid antibodies was inversely proportional to age. In October 2022, prevalence was 84% (95% confidence interval [95% CI]: 75-93%) among 18-29-year-olds, compared to 39% (95% CI: 27-52%) among ≥ 80-year-olds. In most age groups, approximately 40% of COVID-19 cases appear to have been notified via existing surveillance mechanisms. Case notification was highest among individuals older than 80 years and people who had received COVID-19 vaccine booster doses. In vitro neutralisation of Omicron BA.4/BA.5 sub-variants was highest for individuals with evidence of both prior infection and booster vaccination. Conclusions: Under-notification of SARS-CoV-2 infections in the Victorian population is not uniform across age and vaccination strata. Seroprevalence data that give insights into case notification behaviour provide additional context for the interpretation of existing COVID-19 surveillance information.

Relevance of the Aboriginal Rethink Sugary Drink media campaign to Aboriginal and non-Aboriginal audiences in regional Victoria.

OBJECTIVE: To test the hypothesis that a culturally tailored sugar-sweetened beverage (SSB) campaign designed specifically for the Victorian Aboriginal community will not only be valuable for Aboriginal Victorians but will also have cross-over benefits for non-Aboriginal Victorians. METHODS: An online survey was completed by 155 Victorians (78 Aboriginal, 77 non-Aboriginal) four months after the Aboriginal Rethink Sugary Drink (RSD) advertisement was launched. Differences between Aboriginal and non-Aboriginal respondents were assessed using χ2 and Wilcoxon rank-sum tests. RESULTS: Seventy-six per cent of Aboriginal respondents recalled seeing the advertisement compared to 56% of non-Aboriginal respondents (p<0.05). A high proportion of respondents (59% for Aboriginal, 55% for non-Aboriginal) who had seen the advertisement correctly identified the sugar content of a 600mL drink. The perceived relevance of the advertisement was high (78% for Aboriginal vs. 47% for non-Aboriginal; p=0.003), as was the response that it motivated action to improve health (82% vs. 50%; p=0.001). CONCLUSION: Notwithstanding the small sample size, the Aboriginal advertisement appeared to engage both Aboriginal and non-Aboriginal Victorians and promote SSB knowledge and motivation to improve health, particularly among Aboriginal Victorians, who were the target population. Public health campaigns should be designed with Aboriginal Australians to ensure equitable reach and impacts across the whole population. Implications for public health: Aboriginal-led health promotion campaigns may be beneficial for both Aboriginal and non-Aboriginal audiences.

Antimicrobial stewardship in Australian hospitals: how does compliance with antimicrobial stewardship standards compare across key hospital classifications?

BACKGROUND: There is little information on the prevalence and type of antimicrobial stewardship (AMS) activities that are currently occurring in Australian hospitals. OBJECTIVES: To determine what AMS activities are currently occurring in Australian hospitals, identify gaps in compliance with the Australian Commission on Safety and Quality in Health Care (ACSQHC) standards and determine perceived barriers and enablers for implementing AMS programmes. METHODS: A cross-sectional survey open to all Australian hospitals, conducted online and available to hospitals between November 2016 and July 2017. RESULTS: Responses were received from 254 hospitals. Compliance with ACSQHC AMS essential activities was high, except for essential activity 3 (post-prescription reviews), which was conducted by only 39% of respondent hospitals. Importantly, compliance varied by hospital remoteness classification for all activities except essential activity 1 (availability and endorsement of guidelines) and additional activity 4 (publishing antimicrobial susceptibility data annually), with major city hospitals having the highest compliance across all activities. The three most frequently reported barriers to implementing AMS programmes were a lack of training and education, lack of pharmacy resources and a lack of willingness from medical officers to change. CONCLUSIONS: Due to low response rates from certain hospital groups, the survey results are not generalizable to all Australia hospitals. This survey has identified that several gaps in compliance still exist and outlines the need to address lower AMS compliance in hospitals located outside major cities. The key barriers and enablers for AMS programme implementation identified should be used to inform future strategies.

Right sizing for vaccine effectiveness studies: how many is enough for reliable estimation?

Background: The precision of vaccine effectiveness (VE) estimates is dependent on sample size and sampling methods. In Victoria, participating general practitioners (GPs) are not limited by the number of influenza-like illness (ILI) patients they collect respiratory samples (swabs) from in sentinel surveillance. However, in the context of scarce resources it is of interest to determine the minimum sample size needed for reliable estimates. Methods: Following the test-negative design, patients with ILI were recruited by GPs and tested for influenza. Descriptive analyses were conducted to assess possible selection bias introduced by GPs. VE was calculated by logistic regression as [1 ­ odds ratio] x 100% and adjusted for week of presentation and age. Random 20% and 50% samples were selected without replacement to estimate the effect of swab rates on VE estimates. Results: GPs swabbed a smaller proportion of patients aged ≥65 years (45.9%, n=238) than those <5 (75.6%, n=288), 5­17 (67.9%, n=547) and 18­64 (75.6%, n=2662) years. Decreasing the swab rate did not alter VE point estimates significantly. However, it reduced the precision of estimates and in some instances resulted in too small a sample size to estimate VE. Conclusion: Imposing a 20% or 50% swabbing rate produces less robust VE estimates. The number of swabs required per year to produce precise estimates should be dictated by seasonal severity, rather than an arbitrary rate. It would be beneficial for GPs to swab patients systematically by age group to ensure there are sufficient data to investigate VE against a particular subtype in a given age group.

Intraseason decline in influenza vaccine effectiveness during the 2016 southern hemisphere influenza season: A test-negative design study and phylogenetic assessment.

BACKGROUND: We estimated the effectiveness of seasonal inactivated influenza vaccine and the potential influence of timing of immunization on vaccine effectiveness (VE) using data from the 2016 southern hemisphere influenza season. METHODS: Data were pooled from three routine syndromic sentinel surveillance systems in general practices in Australia. Each system routinely collected specimens for influenza testing from patients presenting with influenza-like illness. Next generation sequencing was used to characterize viruses. Using a test-negative design, VE was estimated based on the odds of vaccination among influenza-positive cases as compared to influenza-negative controls. Subgroup analyses were used to estimate VE by type, subtype and lineage, as well as age group and time between vaccination and symptom onset. RESULTS: A total of 1085 patients tested for influenza in 2016 were included in the analysis, of whom 447 (41%) tested positive for influenza. The majority of detections were influenza A/H3N2 (74%). One-third (31%) of patients received the 2016 southern hemisphere formulation influenza vaccine. Overall, VE was estimated at 40% (95% CI: 18-56%). VE estimates were highest for patients immunized within two months prior to symptom onset (VE: 60%; 95% CI: 26-78%) and lowest for patients immunized >4 months prior to symptom onset (VE: 19%; 95% CI: -73-62%). DISCUSSION: Overall, the 2016 influenza vaccine showed good protection against laboratory-confirmed infection among general practice patients. Results by duration of vaccination suggest a significant decline in effectiveness during the 2016 influenza season, indicating immunization close to influenza season offered optimal protection.

Disease burden and health-care clinic attendances for young children in remote aboriginal communities of northern Australia.

OBJECTIVE: To determine the frequency of presentations and infectious-disease burden at primary health care (PHC) services in young children in two remote Aboriginal communities in tropical northern Australia. METHODS: Children born after 1 January 2001, who were resident at 30 September 2005 and for whom consent was obtained, were studied. Clinic records were reviewed for all presentations between 1 January 2002 and 30 September 2005. Data collected included reason for presentation (if infectious), antibiotic prescription and referral to hospital. FINDINGS: There were 7273 clinic presentations for 174 children aged 0-4.75 years, 55% of whom were male. The median presentation rate per child per year was 16 (23 in the first year of life). Upper-respiratory-tract infections (32%) and skin infections (18%) were the most common infectious reasons for presentation. First presentations for scabies and skin sores peaked at the age of 2 months. By 1 year of age, 63% and 69% of children had presented with scabies and skin sores, respectively. CONCLUSION: These Aboriginal children average about two visits per month to PHC centres during their first year of life. This high rate is testament to the disease burden, the willingness of Aboriginal people to use health services and the high workload experienced by these health services. Scabies and skin sores remain significant health problems, with this study describing a previously undocumented burden of these conditions commencing within the first few months of life. Appropriate prevention and treatment strategies should encompass early infancy to reduce the high burden of infectious diseases in this population.

Mapping progress in chronic hepatitis B: geographic variation in prevalence, diagnosis, monitoring and treatment, 2013-15.

OBJECTIVE: To measure progress towards Australia's National Hepatitis B Strategy 2014-17 targets, and assess geographic variation in disease burden and access to care for those living with chronic hepatitis B (CHB). METHODS: Data were generated from routinely collected sources, including risk-group prevalence and population data, infectious diseases notifications, Medicare records, and immunisation registry data, and assessed nationally and according to geographic area for 2013-15. RESULTS: CHB prevalence in 2015 was 239,167 (1.0%), with 62% of those affected having been diagnosed (target 80%). Treatment uptake was 6.1% (target 15%), and only 15.3% of people with CHB received guideline-based care. CHB prevalence ranged within Australia's 31 Primary Health Networks (PHNs) from 1.77% (NT) to 0.56% (Grampians & Barwon South West VIC). No PHN reached the 15% treatment target, with uptake highest in South Western Sydney (13.7%). Immunisation coverage reached the 95% target in three PHNs. CONCLUSIONS: The CHB burden in Australia is significant and highly geographically focused, with notable disparities in access to care across Australia. Implications for public health: Efforts to improve progress toward National Strategy targets should focus on priority areas where the prevalence of CHB is substantial but access to treatment and care remains low.

Infection is the major component of the disease burden in aboriginal and non-aboriginal Australian children: a population-based study.

BACKGROUND: Infection accounts for the majority of pediatric mortality and morbidity in developing countries, but there are limited data on the infectious diseases burden in children from developed countries. We investigated reasons for hospitalization before age 2 years in a birth cohort of Western Australian Aboriginal and non-Aboriginal children. METHODS: Data on live births between January 1990 and December 2000, and corresponding deaths and hospitalizations in the first 2 years of life, were obtained through linked population-based data. RESULTS: Almost half the cohort of 270,068 children were hospitalized at least once. Aboriginal children had significantly higher admission rates (2196 vs. 779 per 1000 live births), stayed longer and were more likely to die in hospital than non-Aboriginal children. Infections (mainly respiratory and gastrointestinal) were the most common reason for hospitalization, accounting for 34% of all admissions, with higher rates in Aboriginal (1114 per 1000 live births) than non-Aboriginal children (242 per 1000) (P < 0.001). Over time, admission rates for infections declined in Aboriginal children but increased in non-Aboriginal children. Aboriginal children were admitted 14 times more often for pneumonia than non-Aboriginal children. CONCLUSIONS: Infections are the leading cause of hospitalization in children under 2 years of age. The continuing heavy burden of serious infections, borne disproportionately by Aboriginal children, needs to be alleviated. Public health interventions such as the development and universal implementation of vaccines for respiratory syncytial virus, rotavirus and influenza are needed, while adequate funding must be committed to Indigenous health services and training.

Upper respiratory tract bacterial carriage in Aboriginal and non-Aboriginal children in a semi-arid area of Western Australia.

BACKGROUND: Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are associated with otitis media (OM). Indigenous children experience particularly high rates of OM. Few studies worldwide have described upper respiratory tract (URT) carriage in Indigenous and non-Indigenous children living in the same area. AIM: The aim of this study was to describe URT bacterial carriage in Aboriginal and non-Aboriginal children in the Kalgoorlie-Boulder area, Western Australia, as part of an investigation into causal pathways to OM. METHODS: Five hundred four and 1045 nasopharyngeal aspirates were collected from 100 Aboriginal and 180 non-Aboriginal children, respectively, followed from birth to age 2 years. Standard procedures were used to identify bacteria. RESULTS: Overall carriage rates of S. pneumoniae, M. catarrhalis and H. influenzae in Aboriginal children were 49%, 50% and 41%, respectively, and 25%, 25% and 11% in non-Aboriginal children. By age 2 months S. pneumoniae and M. catarrhalis had been isolated from 37% and 36% of Aboriginal children and from 11% and 12% of non-Aboriginal children, respectively. From age 3 months onward, carriage rates in Aboriginal children were 51% to 67% for S. pneumoniae and M. catarrhalis and 42% to 62% for H. influenzae; corresponding figures for non-Aboriginal children were 26% to 37% for S. pneumoniae and M. catarrhalis and 11% to 18% for H. influenzae. Non-Aboriginal children had higher carriage rates in winter than in summer, but season had little effect in Aboriginal children. Staphylococcus aureus carriage was highest under age 1 month (55% Aboriginal, 61% non-Aboriginal) and was always higher in non-Aboriginal than Aboriginal children. CONCLUSIONS: Interventions are needed to reduce high transmission and carriage rates, particularly in Aboriginal communities, to avoid the serious consequences of OM.

Aboriginal and non-Aboriginal children in Western Australia carry different serotypes of pneumococci with different antimicrobial susceptibility profiles.

BACKGROUND: Carriage of Streptococcus pneumoniae is considered a precursor to pneumococcal diseases including pneumonia. As part of the Kalgoorlie Otitis Media Research Project, we characterised pneumococci isolated from the nasopharynx of Western Australian Aboriginal and non-Aboriginal children. METHODS: Between 1999 and 2005, 100 Aboriginal and 180 non-Aboriginal children were followed from birth to two years, with nasopharyngeal aspirates collected at ages 1-3 and 6-8 weeks, then at 4, 6, 12, 18 and 24 months. Introduction of 7-valent pneumococcal conjugate vaccine (7vPCV) in 2001 enabled evaluation of its impact on carriage in study participants according to vaccines doses received. Pneumococcal serotyping was performed by Quellung and antimicrobial susceptibility by disk diffusion and Etest®. Molecular epidemiology of pneumococcal isolates was investigated by pulse-field gel electrophoresis and multilocus sequence typing. RESULTS: Overall, the prevalence of 7vPCV serotypes was similar for Aboriginal and non-Aboriginal children (19 % vs. 16 %), but the prevalence of non-vaccine serotypes was higher in Aboriginal children (22 % vs. 7 %). A multi-resistant 6B clone (ST90) was found only in non-Aboriginal children. Aboriginal children who received three doses of 7vPCV had lower odds of carrying 7vPCV serotypes (odds ratio [OR] 0.19, 95 % CI 0.08-0.44) and higher odds of carrying non-vaccine serotypes (OR 2.37, 95 % CI 1.13-4.99) than unvaccinated Aboriginal children; this finding was not observed in non-Aboriginal children. CONCLUSIONS: This unique study shows important differences in pneumococcal serotypes, genotypes, and antimicrobial susceptibility between Aboriginal and non-Aboriginal children living in the same geographic area before widespread 7vPCV use, and highlights the need for ongoing post-vaccination surveillance in outback Australia.

Understanding influenza vaccine protection in the community: an assessment of the 2013 influenza season in Victoria, Australia.

BACKGROUND: The influenza virus undergoes frequent antigenic drift, necessitating annual review of the composition of the influenza vaccine. Vaccination is an important strategy for reducing the impact and burden of influenza, and estimating vaccine effectiveness (VE) each year informs surveillance and preventative measures. We aimed to describe the influenza season and to estimate the effectiveness of the influenza vaccine in Victoria, Australia, in 2013. METHODS: Routine laboratory notifications, general practitioner sentinel surveillance (including a medical deputising service) data, and sentinel hospital admission surveillance data for the influenza season (29 April to 27 October 2013) were collated in Victoria, Australia, to describe influenza-like illness or confirmed influenza during the season. General practitioner sentinel surveillance data were used to estimate VE against medically-attended laboratory confirmed influenza. VE was estimated using the case test negative design as 1-adjusted odds ratio (odds of vaccination in cases compared with controls) × 100%. Cases tested positive for influenza while non-cases (controls) tested negative. Estimates were adjusted for age group, week of onset, time to swabbing and co-morbidities. RESULTS: The 2013 influenza season was characterised by relatively low activity with a late peak. Influenza B circulation preceded that of influenza A(H1)pdm09, with very little influenza A(H3) circulation. Adjusted VE for all influenza was 55% (95%CI: -11, 82), for influenza A(H1)pdm09 was 43% (95%CI: -132, 86), and for influenza B was 56% (95%CI: -51, 87) Imputation of missing data raised the influenza VE point estimate to 64% (95%CI: 13, 85). CONCLUSIONS: Clinicians can continue to promote a positive approach to influenza vaccination, understanding that inactivated influenza vaccines prevent at least 50% of laboratory-confirmed outcomes in hospitals and the community.