COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals.

BACKGROUND: The Global COVID Vaccine Safety (GCoVS) Project, established in 2021 under the multinational Global Vaccine Data Network™ (GVDN®), facilitates comprehensive assessment of vaccine safety. This study aimed to evaluate the risk of adverse events of special interest (AESI) following COVID-19 vaccination from 10 sites across eight countries. METHODS: Using a common protocol, this observational cohort study compared observed with expected rates of 13 selected AESI across neurological, haematological, and cardiac outcomes. Expected rates were obtained by participating sites using pre-COVID-19 vaccination healthcare data stratified by age and sex. Observed rates were reported from the same healthcare datasets since COVID-19 vaccination program rollout. AESI occurring up to 42 days following vaccination with mRNA (BNT162b2 and mRNA-1273) and adenovirus-vector (ChAdOx1) vaccines were included in the primary analysis. Risks were assessed using observed versus expected (OE) ratios with 95 % confidence intervals. Prioritised potential safety signals were those with lower bound of the 95 % confidence interval (LBCI) greater than 1.5. RESULTS: Participants included 99,068,901 vaccinated individuals. In total, 183,559,462 doses of BNT162b2, 36,178,442 doses of mRNA-1273, and 23,093,399 doses of ChAdOx1 were administered across participating sites in the study period. Risk periods following homologous vaccination schedules contributed 23,168,335 person-years of follow-up. OE ratios with LBCI > 1.5 were observed for Guillain-Barré syndrome (2.49, 95 % CI: 2.15, 2.87) and cerebral venous sinus thrombosis (3.23, 95 % CI: 2.51, 4.09) following the first dose of ChAdOx1 vaccine. Acute disseminated encephalomyelitis showed an OE ratio of 3.78 (95 % CI: 1.52, 7.78) following the first dose of mRNA-1273 vaccine. The OE ratios for myocarditis and pericarditis following BNT162b2, mRNA-1273, and ChAdOx1 were significantly increased with LBCIs > 1.5. CONCLUSION: This multi-country analysis confirmed pre-established safety signals for myocarditis, pericarditis, Guillain-Barré syndrome, and cerebral venous sinus thrombosis. Other potential safety signals that require further investigation were identified.

Measuring school level attributable risk to support school-based HPV vaccination programs.

BACKGROUND: In Australia in 2017, 89% of 15-year-old females and 86% of 15-year-old males had received at least one dose of the HPV vaccine. However, considerable variation in HPV vaccination initiation (dose one) across schools remains. It is important to understand the school-level characteristics most strongly associated with low initiation and their contribution to the overall between-school variation. METHODS: A population-based ecological analysis was conducted using school-level data for 2016 on all adolescent students eligible for HPV vaccination in three Australian jurisdictions. We conducted logistic regression to determine school-level factors associated with lower HPV vaccination initiation (< 75% dose 1 uptake) and estimated the population attributable risk (PAR) and the proportion of schools with the factor (school-level prevalence). RESULTS: The factors most strongly associated with lower initiation, and their prevalence were; small schools (OR = 9.3, 95%CI = 6.1-14.1; 33% of schools), special education schools (OR = 5.6,95%CI = 3.7-8.5; 8% of schools), higher Indigenous enrolments (OR = 2.7,95% CI:1.9-3.7; 31% of schools), lower attendance rates (OR = 2.6,95%CI = 1.7-3.7; 35% of schools), remote location (OR = 2.6,95%CI = 1.6-4.3; 6% of schools,) and lower socioeconomic area (OR = 1.8,95% CI = 1.3-2.5; 33% of schools). The highest PARs were small schools (PAR = 79%, 95%CI:76-82), higher Indigenous enrolments (PAR = 38%, 95%CI: 31-44) and lower attendance rate (PAR = 37%, 95%CI: 29-46). CONCLUSION: This analysis suggests that initiatives to support schools that are smaller, with a higher proportion of Indigenous adolescents and lower attendance rates may contribute most to reducing the variation of HPV vaccination uptake observed at a school-level in these jurisdictions. Estimating population-level coverage at the school-level is useful to guide policy and prioritise resourcing to support school-based vaccination programs.

Differences in school factors associated with adolescent HPV vaccination initiation and completion coverage in three Australian states.

BACKGROUND: Schools are the primary setting for the delivery of adolescent HPV vaccination in Australia. Although this strategy has achieved generally high vaccination coverage, gaps persist for reasons that are mostly unknown. This study sought to identify school-level correlates of low vaccination course initiation and completion in New South Wales, Tasmania, and Western Australia to inform initiatives to increase uptake. METHODS: Initiation was defined as the number of first doses given in a school in 2016 divided by vaccine-eligible student enrolments. Completion was the number of third doses given in a school in 2015-2016 divided by the number of first doses. Low initiation and completion were defined as coverage ≤ 25thpercentile of all reporting schools. We investigated correlations between covariates using Spearman's rank correlation coefficients. Due to multicollinearity, we used univariable logistic regression to investigate associations between school characteristics and low coverage. RESULTS: Median initiation was 84.7% (IQR: 75.0%-90.4%) across 1,286 schools and median completion was 93.8% (IQR: 86.0%-97.3%) across 1,295 schools. There were strong correlations between a number of school characteristics, particularly higher Indigenous student enrolments and lower attendance, increasing remoteness, higher postcode socioeconomic disadvantage, and smaller school size. Characteristics most strongly associated with low initiation in univariate analyses were small school size, location in Tasmania, and schools catering for special educational needs. Low completion was most strongly associated with schools in Tasmania and Western Australia, remote location, small size, high proportion of Indigenous student enrolments, and low attendance rates. CONCLUSION: This study provides indicative evidence that characteristics of schools and school populations are associated with the likelihood of low initiation and completion of the HPV vaccination course. The findings will guide further research and help target initiatives to improve vaccination uptake in schools with profiles associated with lower coverage.

Q fever seroprevalence in Australia suggests one in twenty people have been exposed.

Q fever (caused by Coxiella burnetii) is thought to have an almost world-wide distribution, but few countries have conducted national serosurveys. We measured Q fever seroprevalence using residual sera from diagnostic laboratories across Australia. Individuals aged 1-79 years in 2012-2013 were sampled to be proportional to the population distribution by region, distance from metropolitan areas and gender. A 1/50 serum dilution was tested for the Phase II IgG antibody against C. burnetii by indirect immunofluorescence. We calculated crude seroprevalence estimates by age group and gender, as well as age standardised national and metropolitan/non-metropolitan seroprevalence estimates. Of 2785 sera, 99 tested positive. Age standardised seroprevalence was 5.6% (95% confidence interval (CI 4.5%-6.8%), and similar in metropolitan (5.5%; 95% CI 4.1%-6.9%) and non-metropolitan regions (6.0%; 95%CI 4.0%-8.0%). More males were seropositive (6.9%; 95% CI 5.2%-8.6%) than females (4.2%; 95% CI 2.9%-5.5%) with peak seroprevalence at 50-59 years (9.2%; 95% CI 5.2%-13.3%). Q fever seroprevalence for Australia was higher than expected (especially in metropolitan regions) and higher than estimates from the Netherlands (2.4%; pre-outbreak) and US (3.1%), but lower than for Northern Ireland (12.8%). Robust country-specific seroprevalence estimates, with detailed exposure data, are required to better understand who is at risk and the need for preventive measures.

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

BACKGROUND: Most studies use indirect cohort or case-control methods to estimate vaccine effectiveness (VE) of 7- and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13) against invasive pneumococcal disease (IPD). Neither method can measure the benefit vaccination programs afford the unvaccinated and many studies were unable to estimate dose-specific VE. We linked Australia's national immunisation register with health data from two states to calculate IPD incidence by vaccination status and VE for a 3 + 0 PCV schedule (doses at 2, 4, 6 months, no booster) among a cohort of 1.4 million births. METHODS: Births records for 2001-2012 were probabilistically linked to IPD notifications, hospitalisations, deaths, and vaccination history (available until December 2013). IPD rates in vaccinated and unvaccinated children <2 years old were compared using Cox proportional hazards models (adjusting for potential confounders), with VE = (1 - adjusted hazard ratio) × 100. Separate models were performed for all-cause, PCV7, PCV13 and PCV13-non-PCV7 serotype-specific IPD, and for Aboriginal and non-Aboriginal children. RESULTS: Following introduction of universal PCV7 in 2005, rates of PCV7 serotype and all-cause IPD in unvaccinated children declined 89.5% and 61.4%, respectively, to be similar to rates in vaccinated children. Among non-Aboriginal children, VEs for 3 doses were 94.2% (95%CI: 81.9-98.1) for PCV7 serotype-specific IPD, 85.6% (95%CI: 60.5-94.8) for PCV13-non-PCV7 serotype-specific IPD and 80.1% (95%CI: 59.4-90.3) for all-cause IPD. There were no statistically significant differences between the VEs for 3 doses and for 1 or 2 doses against PCV13 and PCV13-non-PCV7 serotype-specific IPD, or between Aboriginal and non-Aboriginal children. CONCLUSION: Our population-based cohort study demonstrates that >90% coverage in the first year of a universal 3 + 0 PCV program provided high population-level protection, predominantly attributable to strong herd effects. The size of the cohort enabled calculation of robust dose-specific VE estimates for important population sub-groups relevant to vaccination policies internationally.

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

INTRODUCTION: Several countries have developed national immunisation registers, but only the Nordic countries have linked their registers to other health data in order to comprehensively evaluate the `real world' effectiveness of vaccines. Nordic countries can link datasets deterministically using the national person identifier, but most countries, including Australia, don't have such an identifier to enable this type of linkage. OBJECTIVES: To describe the process for assembling a linked study cohort that will enable the conduct of population-based studies related to immunisation and immunisation policy. METHODS: National death and immunisation databases along with state health data (notifications of vaccine preventable diseases, perinatal data, hospital admissions and emergency department presentations) up until December 2013 were probabilistically linked (using demographic details) for children born between 1996 and 2012 in two states: Western Australia and New South Wales (42% of Australia's population, combined). RESULTS: After exclusions there were 1.95 million children in the study cohort (live born children with both a birth and perinatal record which represents 97.5% of all live births in the state perinatal data collections - our source population) and 18.0 million person years of follow up (mean: 9.2 years per child). The characteristics of children in the cohort were generally similar to those only included in state perinatal databases and outcome measures were in keeping with expected figures from unlinked data sources. However, the lack of a dynamic national population register meant immigrants could not be included. CONCLUSIONS: We have been able to develop a similarly comprehensive system to the Nordic countries based on probabilistic linkage methods. Our experience should provide encouragement to other countries with national immunisation registers looking to establish similar systems.

Verification of measles elimination in Australia: Application of World Health Organization regional guidelines.

BACKGROUND: The World Health Organization (WHO) Western Pacific Region (WPR) Guidelines on verification of measles elimination were established in 2012. This article outlines Australia's approach to addressing the guideline's five lines of evidence, which led to formal verification of elimination by the WHO Regional Verification Commission (RVC) in March 2014. METHODS: The criteria were addressed using national measles notifications, data from selected laboratories, the national childhood immunization register, and three national serosurveys (1998/1999, 2002, 2007). RESULTS: Australia met or exceeded all indicator targets with either national or sentinel data. Laboratory and epidemiological surveillance were of high quality, with 85% of cases documented as imported/import-related (target 80%); coverage with the first dose of measles vaccine was close to 94% in 2008-2012 and second dose coverage increased to 91% in 2012 (target >95%). There is ongoing commitment by the Australian Government to increase immunization coverage, and the absence of sustained transmission of any single measles genotype was demonstrated. CONCLUSIONS: This is the first documentation of the successful application of the WPR RVC guidelines. The indicators afford some flexibility but appear to provide appropriate rigor to judge achievement of measles elimination. Our experience could assist other countries seeking to verify their elimination status.

Hospitalisation rates and associated factors in community-based cohorts of HIV-infected and -uninfected gay and bisexual men.

OBJECTIVES: There is evidence that HIV-positive patients are suffering from a greater burden of morbidity as they age due to nonAIDS-related complications. To date it has been difficult to determine what part of this excess risk is due to the health effects of HIV, its treatment or to lifestyle factors common to gay and bisexual men (GBM). We calculated overall and cause-specific hospitalisation rates and risk factors for hospitalisations in HIV-negative and HIV-positive cohorts of GBM and compare these with rates in the general male population. METHODS: We conducted a record linkage study, linking two cohorts of HIV-negative (n = 1325) and HIV-positive (n = 557) GBM recruited in Sydney, New South Wales (NSW), Australia with the NSW hospital discharge data register. We compared rates of hospitalisation in the two cohorts and risk factors for hospitalisation using random-effects Poisson regression methods. Hospitalisation rates for each cohort were further compared with those in the general male population using indirect standardisation. RESULTS: We observed 2032 hospitalisations in the HIV-negative cohort during 13,016 person-years (PYs) [crude rate: 15.6/100 PYs (95% CI: 14.9-16.3)] and 2130 hospitalisations in the HIV-positive cohort during 5571 PYs [crude rate: 38.2/100 PYs (95% CI: 36.6-39.9)]. HIV-positive individuals had an increased risk of hospitalisation compared with the HIV-negative individuals [adjusted-IRR: 2.34 (95% CI: 1.91-2.86)] and the general population [SHR: 1.45 (95% CI: 1.33-1.59)]. Hospitalisation rates were lower in the HIV-negative cohort compared with the general population [SHR: 0.72 (95% CI: 0.67-0.78)]. The primary causes of hospitalisation differed between groups. CONCLUSIONS: HIV-positive GBM continue to experience excess morbidity compared with HIV-negative GBM men and the general population. HIV-negative GBM had lower morbidity compared with the general male population suggesting that GBM identity does not confer excess risk.

Hepatitis B immunity in Australia: a comparison of national and prisoner population serosurveys.

In Australia, hepatitis B (HBV) vaccination is recommended for injecting drug users (IDUs), Indigenous adults and prisoners. We compared immunity to HBV in prisoners and the general population obtained from national serosurveys in 2007. Individuals with HBV surface antibody (HBsAb) positive sera were considered immune from past infection [HBV core antibody (HBcAb) positive] or from vaccination (HBcAb negative). Male prisoners aged 18-58 years had a higher HBsAb seroprevalence than the general population (46·4% vs. 39·4%, P = 0·061). Comparison of HBcAb results was possible for males aged 18-29 years. In this group, higher HBsAb seroprevalence was due to past infection (12·9% vs. 3·0%, P < 0·001), rather than vaccine-conferred immunity (35·3% vs. 43·4%, P = 0·097). All prisoner groups, but especially IDUs, those of Indigenous heritage or those with a previous episode of imprisonment had higher levels of immunity from past infection than the general population (19·3%, 33·0%, 17·1%, respectively, vs. 3·0%, P < 0·05). Indigenous prisoners, non-IDUs and first-time entrants had significantly lower levels of vaccine-conferred immunity than the general population (26·4%, 26·2% and 20·7% respectively vs. 43·4%, P < 0·05). Improving prison-based HBV vaccination would prevent transmission in the prison setting and protect vulnerable members of the community who are at high risk of both infection and entering the prison system.

Control of varicella in the post-vaccination era in Australia: a model-based assessment of catch-up and infant vaccination strategies for the future.

In Australia, varicella vaccine was universally funded in late 2005 as a single dose at 18 months. A school-based catch-up programme for children aged 10-13 years without a history of infection or vaccination was funded until 2015, when those eligible for universal infant vaccination would have reached the age of high school entry. This study projects the impact of discontinuing catch-up vaccination on varicella and zoster incidence and morbidity using a transmission dynamic model, in comparison with alternative policy options, including two-dose strategies. At current vaccine coverage (83% at 2 years and 90% at 5 years), ceasing the adolescent catch-up programme in 2015 was projected to increase varicella-associated morbidity between 2035 and 2050 by 39%. Although two-dose infant programmes had the lowest estimated varicella morbidity, the incremental benefit from the second dose fell by 70% if first dose coverage increased from 83% to 95% by age 24 months. Overall zoster morbidity was predicted to rise after vaccination, but differences between strategies were small. Our results suggest that feasibility of one-dose coverage approaching 95% is an important consideration in estimating incremental benefit from a second dose of varicella vaccine.

Decreased varicella and increased herpes zoster incidence at a sentinel medical deputising service in a setting of increasing varicella vaccine coverage in Victoria, Australia, 1998 to 2012.

We performed an ecological study using sentinel consultation data from a medical deputising service to assess the impact of increasing coverage with childhood varicella vaccine on the incidence risk of varicella and zoster in the population served by the deputising service in Victoria, Australia from 1998 to 2012. Following a successful vaccination programme, the incidence of varicella in Australia was modelled to decrease and the incidence of zoster to increase, based on a theoretical decrease in boosting of zoster immunity following a decrease in wild varicella virus circulation due to vaccination. Incidence risks (consultation proportions for varicella and zoster) were directly age-standardised to the Melbourne population in 2000, when varicella vaccine was first available. Age-standardised varicella incidence risk peaked in 2000 and halved by 2012. Age-standardised zoster incidence risk remained constant from 1998 to 2002, but had almost doubled by 2012. The increase in zoster consultations largely reflected increases in people younger than 50 years-old. Although causality cannot be inferred from ecological studies, it is generally agreed that the decrease in varicella incidence is due to increasing varicella vaccine coverage. The possible indirect effect of the vaccine on zoster incidence is less clear and ongoing monitoring of zoster is required.

General practice encounters following seasonal influenza vaccination as a proxy measure of early-onset adverse events.

BACKGROUND: In 2010, use of seasonal trivalent influenza vaccine (TIV) in children <5 years of age was suspended in Australia following reports of vaccine-related febrile convulsions. We investigated the utility of data on primary care [general practice (GP)] consultations for any reason within three days of receipt of influenza vaccine as recorded on the Australian Childhood Immunisation Register (ACIR) as a means of signal detection. METHODS: Data on GP consultations were obtained from Medicare Australia (Australian Government Department of Human Services) for children recorded on the ACIR as receiving either TIV or monovalent influenza vaccine. Rates of GP consultation by day following ACIR-recorded receipt of influenza vaccine were compared by year (2008-2010), vaccine type, age and region. RESULTS: In 2010, GP encounter rates on the day after receipt of the TIV manufactured by bioCSL (formerly CSL Biotherapies (Fluvax(®)) were significantly higher than both bioCSL TIVs in the previous two years [rate ratio (RR) 1.9; 95% CI: 1.7-2.2] and Sanofi Pasteur TIV, Vaxigrip(®) [RR 1.6, 95% CI 1.4-1.7] in 2009-2010. Encounter rates were also higher than for CSL Monovalent influenza vaccine, Panvax(®) [RR 1.9, 95% CI 1.7-2.2] in 2009-2010. These findings were robust to adjustment for age group (≤ 2, >2 years) and region (Western Australia vs other Australian states/territories). CONCLUSIONS: A primary care consultation on the day after vaccine receipt is a reasonable proxy for early reactogenicity and has potential for use in various settings.

Laboratory surveillance of invasive pneumococcal disease in New South Wales, Australia, before and after introduction of 7-valent conjugate vaccine: reduced disease, but not antibiotic resistance rates.

We compared serotype distributions of Streptococcus pneumoniae isolates from patients aged <5 and o5 years with invasive pneumococcal disease in New South Wales, Australia, and antibiotic susceptibilities of isolates from the <5 years age group only, before (2002­2004) and after(2005­2009) introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). Overall, there were significant decreases in the mean annual number of referred isolates (770 vs. 515) and the proportion belonging to PCV7 serotypes (74% vs. 38%), but non-PCV7 serotypes, particularly 19A, increased (5% vs. 18%). All changes were more marked in the <5 years age group.Susceptibility testing of isolates from the <5 years age group showed variation in resistance between serotypes, but significant overall increases in penicillin non-susceptibility (23% vs. 31%),ceftriaxone resistance (2% vs. 12%) and multidrug resistance (4% vs. 7%) rates ; erythromycin resistance fell (32% vs. 25%). Continued surveillance is needed to monitor changes following the introduction of 13-valent PCV in 2012.

Changes in seroprevalence to hepatitis A in Victoria, Australia: a comparison of three time points.

Serological data provide an important measure of past exposure and immunity to hepatitis A virus (HAV) infection in a population. National serosurveys from developed countries have typically indicated a decline in HAV seroprevalence over time as sanitation levels improve. We examined trends in the seroepidemiology of HAV antibodies in Victoria, Australia, drawing on cross-sectional samples taken at three time points over a 20-year period. Stored sera from 1988 (n=753), 1998 (n=1091), and 2008 (n=791) from persons aged 1-69 years were obtained from the state of Victoria, Australia. The within-year population adjusted results show a significant trend of increasing population HAV seroprevalence over time from 34.3% (95% CI 31.7-36.9) in 1988, to 40.0% (95% CI 37.1-42.8) in 1998 and 55.1% (95% CI 52.1-58.1) in 2008, P<0.0001. A particularly noticeable rise in population seroprevalence was observed between 1998 and 2008 for those aged 5-39 years. The increase in HAV seropositivity over time is in contrast to the declining rates of disease notification in Australia. Based on comparisons with other Australian data, it appears the increase in population seroprevalence over the last two decades is unlikely to be due to endemic transmission of infection. Instead, other factors, including increases in travel to HAV endemic regions, migration to Australia from HAV endemic regions and vaccine uptake are more likely causes. Ongoing monitoring of serological HAV profiles in the population is required to determine future policy direction to prevent increased burden.

Trends in incidence of hepatocellular carcinoma after diagnosis of hepatitis B or C infection: a population-based cohort study, 1992-2007.

Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are the major risk factors for hepatocellular carcinoma (HCC). We examined trends in the incidence of HCC among a population-based cohort of people infected with HBV or HCV. HBV and HCV cases notified to the New South Wales Health Department between 1992 and 2007 were linked to the Central Cancer Registry, Registry of Births, Deaths and Marriages, and National HIV/AIDS Registries. Crude HCC incidence rates were estimated using person-time methodology. Age-standardized incidence rates were calculated using the 2001 Australian population. Trends in incidence were examined using join point regression models. Between 1992 and 2007, 1201 people had a linked HCC record: 556 of those with HBV; 592 with HCV; 45 with HBV/HCV co-infection; and 8 with HIV co-infection. The overall age-standardized HCC incidence rates declined non-significantly from 148.0 (95% confidence intervals (CI) 63.7, 287.4) per 100,000 population in 1995 to 101.2 (95% CI 67.3, 144.6) in 2007 among the HBV monoinfected group and significantly from 151.8 (95% CI 62.4, 299.8) per 100,000 population to 75.3 (95% CI 50.8, 105.5) among the HCV monoinfected group. However, incidence rates in the HCV monoinfected group progressively increased from the period 1992-1997 to 2004-2007 when adjusted for age, sex, and birth cohort, and the total number of cases per annum continued to increase. Despite declines in the age-adjusted incidence rates of HCC over time, the absolute number of cases increased likely due to the ageing cohort and an increasing prevalence of both hepatitis B and C in Australia.

Hospitalization rates associated with hepatitis B and HIV co-infection, age and sex in a population-based cohort of people diagnosed with hepatitis C.

To determine the extent age, sex and co-infection affect morbidity in people infected with hepatitis C virus (HCV), we performed a population-based study linking HCV notifications in New South Wales, Australia with their hospital (July 2000 to June 2006), hepatitis B virus (HBV) and HIV notification, and death records. Poisson models were used to calculate hospitalization rate ratios (RRs) for all-cause, illicit drug and liver-related admissions. Co-infection RRs were used to estimate attributable risk (AR). The 86 501 people notified with HCV contributed 422 761 person-years of observation; 0·8% had HIV, 3·7% HBV, and 0·04% had both. RRs for males were equal to or lower than for females in younger ages, but higher in older ages (P for interaction ⩽0·013). HBV/HIV co-infection resulted in ARs of over 70% for liver disease and 30-60% otherwise. However, at the cohort level the impact was minimal (population ARs 1·3-8·7%). Our findings highlight the importance and success of public health measures, such as needle and syringe exchange programmes, which have helped to minimize the prevalence of co-infection in Australia. The findings also suggest that the age of study participants needs to be considered whenever the burden of HCV-related morbidity is reported by sex. The results are likely to be representative of patterns in hospital-related morbidity for the entire HCV-infected population in Australia and the ARs generalizable to other developed countries.

Ureaplasma urealyticum is significantly associated with non-gonococcal urethritis in heterosexual Sydney men.

We investigated the prevalence of various genital organisms in 268 men with (cases) and 237 men without (controls) urethral symptoms/signs (urethral discharge, dysuria and/or urethral irritation) from two sexual health clinics in Sydney between April 2006 and November 2007. The presence of urethral symptoms/signs was defined as non-gonococcal urethritis (NGU) for this study. Specific aims were to investigate the role of Ureaplasma urealyticum in NGU and the prevalence of Mycoplasma genitalium in our population. Multiplex polymerase chain reaction-based reverse line blot (mPCR/RLB) assay was performed to detect 14 recognized or putative genital pathogens, including Chlamydia trachomatis, M. genitalium, U. urealyticum and U. parvum. U. urealyticum was associated with NGU in men without another urethral pathogen (odds ratio [OR] 2.0, 95% confidence interval [CI] 1.1-3.8; P = 0.04); this association remained after controlling for potential confounding by age and history of unprotected vaginal sex in the last four weeks (OR 2.0, 95% CI: 1.1-3.9; P = 0.03). C. trachomatis (OR 7.5, P < 0.001) and M. genitalium (OR 5.5, P = 0.027) were significantly associated with NGU. The prevalence of M. genitalium was low (4.5% cases, 0.8% controls). U. urealyticum is independently associated with NGU in men without other recognized urethral pathogens. Further research should investigate the role of U. urealyticum subtypes among heterosexual men with NGU.

Modelling the impact of one-dose vs. two-dose vaccination regimens on the epidemiology of varicella zoster virus in Australia.

We examined the impact of one-dose vs. two-dose vaccination strategies on the epidemiology of varicella zoster virus (VZV) in Australia, using a mathematical model. Strategies were assessed in terms of varicella (natural and breakthrough) and zoster incidence, morbidity, average age of infection and vaccine effectiveness (VE). Our modelling results suggest that compared to a one-dose vaccination strategy (Australia's current vaccination schedule), a two-dose strategy is expected to not only produce less natural varicella cases (5% vs. 13% of pre-vaccination state, respectively) but also considerably fewer breakthrough varicella cases (only 11.4% of one-dose strategy). Therefore a two-dose infant vaccination programme would be a better long-term strategy for Australia.

The utility of seroepidemiology for tracking trends in pertussis infection.

Comparing pertussis epidemiology over time and between countries is confounded by differences in diagnostic and notification practices. Standardized serological methods applied to population-based samples enhance comparability. Population prevalence of different levels of pertussis toxin IgG (PT IgG) antibody, measured by standardized methods, were compared by age group and region of Australia between 1997/1998 and 2002. The proportion of 5- to 9-year-olds with presumptive recent pertussis infection (based on IgG levels >or=62.5 ELISA units/ml) significantly decreased in 2002, consistent with notification data for the same period and improved uptake of booster vaccines following the schedule change from whole-cell to acellular vaccine. In contrast, recent presumptive infection significantly increased in adults aged 35-49 years. Population-based serosurveillance using standardized PT IgG antibody assays has the potential to aid interpretation of trends in pertussis incidence in relation to vaccine programmes and between countries.