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Although coverage with 2 doses of COVID-19 vaccine rapidly reached >95% in adults in Australia by late 2021 (1), by December 4, 2022, uptake had slowed and plateaued at much [...]

Introduction: Query (Q) fever is a zoonosis caused by the bacterium Coxiella burnetii typically presenting as an influenza-like illness (ILI) with or without hepatitis. The infection may be missed by clinicians in settings of low endemicity, as the presentation is clinically not specific, and there are many more common differential diagnoses for ILI including SARS-CoV-2 infection. Methods: Residual serum samples were retrospectively tested for Phase 1 and 2 Q fever-specific IgM, IgG, IgA antibodies by indirect immunofluorescence and C. burnetii DNA by polymerase chain reaction. They had not been previously tested for Q fever, originating from undiagnosed patients with probable ILI, aged 10–70 years and living in regional New South Wales, Australia. The results were compared with contemperaneous data on acute Q fever diagnostic tests which had been performed based on clinicians requests from a geographically similar population. Results: Only one (0.2%) instance of missed acute Q fever was identified after testing samples from 542 eligible patients who had probable ILI between 2016–2023. Laboratory data showed that during the same period, 731 samples were tested for acute Q fever for clinician-initiated requests and of those 70 (9.6%) were positive. Probability of being diagnosed with Q fever after a clinician initiated request was similar regardless of the patients sex, age and the calendar year of sampling. Conclusion: In this sample, Q fever was most likely to be diagnosed via clinician requested testing rather than by testing of undiagnosed patients with an influenza like illness. Author summary: Q fever is a highly contagious infection presenting as an influenza-like illness or less commonly as acute hepatitis. Literature shows that there may be diagnostic delays in recognizing Q fever by primary care physicians if they are unfamiliar with the infection. We tested residual serum samples stored at NSW Health Pathology between 2016–2023 for Q fever, if that sample originated from a rural postcode in NSW and had been tested previously for an organism causing influenza like illnesses, but not Q fever. After testing 542 eligible samples only one case of missed acute Q fever was found. In the same period, from a similar population the same diagnostic laboratory received 731 requests for Q fever testing from which 70 were positive. Therefore, In this study the number of missed acute Q fever cases were clinically insignificant. [ABSTRACT FROM AUTHOR]

Background Vaccine-preventable infections are generally well controlled in Australia. However, gaps in immunity can lead to outbreaks and are important to identify. Young adults are a highly mobile population and a potential source of imported infections. We aimed to evaluate anti- measles, mumps, rubella and varicella (MMR&V) IgG seroprevalence and explore factors relating to antibody seropositivity. Methods A cross-sectional online survey was conducted among students from a large Australian university to collect demographic, vaccination, infection and travel characteristics. Blood samples were collected to measure MMR&V seroprevalence. Logistic regression was used to identify factors associated with seropositivity. Results Among 804 university students, seroprevalence (positive or equivocal) for measles was 82.3% (95% CI 79.6–84.8%), mumps 79.5% (95% CI 76.7–82.3%), rubella 91.5% (95% CI 89.6–93.5%) and varicella 86.2% (95% CI 84.1–88.8%), with 452 (56.2%, 95% CI 52.8–59.6) seropositive to all four viruses. Varicella seropositivity was highest in the older birth cohort (born 1988–1991). Measles seropositivity was higher for international students compared to domestic students. Among international students, mumps seroprevalence was significantly lower than measles and rubella seroprevalence. International travel in the previous 12 months was reported by 63.1% of students, but only 18.2% of travellers reported seeking pre-travel health advice prior to most recent international travel. Conclusions Overall, this study suggests immunity to MMR&V is sub-optimal. We found the university student population to be highly mobile and unlikely to seek pre-travel advice; thus, they are a potential source of infection importation. The implementation of university immunization policies could address the gaps identified and our findings can inform the development of targeted vaccination campaigns. [ABSTRACT FROM AUTHOR]

Background There is limited empiric evidence on the coverage of pneumococcal conjugate vaccines (PCVs) required to generate substantial indirect protection. We investigate the association between population PCV coverage and indirect protection against invasive pneumococcal disease (IPD) and pneumonia hospitalisations among undervaccinated Australian children. Methods and findings Birth and vaccination records, IPD notifications, and hospitalisations were individually linked for children aged There were strong inverse associations between PCV coverage and the incidence of PCV7-type IPD (adjusted incidence rate ratio [aIRR] 0.967, 95% confidence interval [CI] 0.958 to 0.975, p-value < 0.001), and pneumonia hospitalisations (all-cause pneumonia: aIRR 0.991 95% CI 0.990 to 0.994, p-value < 0.001) among undervaccinated children. Subgroup analyses for children Conclusions In this study, we observed substantial indirect protection at lower levels of PCV coverage than previously described-challenging assumptions that high levels of PCV coverage (i.e., greater than 90%) are required. Understanding the association between PCV coverage and indirect protection is a priority since the control of vaccine-type pneumococcal disease is a prerequisite for reducing the number of PCV doses (from 3 to 2). Reduced dose schedules have the potential to substantially reduce program costs while maintaining vaccine impact., Author(s): Jocelyn Chan 1,2,*, Heather F. Gidding 3,4,5, Christopher C. Blyth 6, Parveen Fathima 7, Sanjay Jayasinghe 5,8, Peter B. McIntyre 5, Hannah C. Moore 7, Kim Mulholland 1,2,9, Cattram [...]

Background Previous Australian studies have shown that delayed vaccination with each of the three primary doses of diphtheria-tetanus-pertussis-containing vaccines (DTP) is up to 50 % in certain subpopulations. We estimated the excess burden of pertussis that might have been prevented if (i) all primary doses and (ii) each dose was given on time. Methods Perinatal, immunization, pertussis notification and death data were probabilistically linked for 1 412 984 infants born in two Australian states in 2000–12. A DTP dose administered >15 days after the recommended age was considered delayed. We used Poisson regression models to compare pertussis notification rates to 1-year of age in infants with ≥1 dose delayed (Aim 1) or any individual dose delayed (Aim 2) versus a propensity weighted counterfactual on-time cohort. Results Of all infants, 42% had ≥1 delayed DTP dose. We estimated that between 39 to 365 days of age, 85 (95% CI: 61–109) cases per 100 000 infants, could have been prevented if all infants with ≥1 delayed dose had received their three doses within the on-time window. Risk of pertussis was higher in the delayed versus the on-time cohort, so crude rates overestimated the excess burden (110 cases per 100 000 infants (95% CI: 95–125)). The estimated dose-specific excess burden per 100 000 infants was 132 for DTP1, 50 for DTP2 and 19 for DTP3. Conclusions We provide robust evidence that improved DTP vaccine timeliness, especially for the first dose, substantially reduces the burden of infant pertussis. Our methodology, using a potential outcomes framework, is applicable to other settings. [ABSTRACT FROM AUTHOR]

Objective To estimate the measles effective reproduction number (R) in Australia by modelling routinely collected notification data. Methods R was estimated for 2009-2011 by means of three methods, using data from Australia's National Notifiable Disease Surveillance System. Method 1 estimated R as 1 -P, where P equals the proportion of cases that were imported, as determined from data on place of acquisition. The other methods estimated R by fitting a subcritical branching process that modelled the spread of an Infection with a given R to the observed distributions of outbreak sizes (method 2) and generations of spread (method 3). Stata version 12 was used for method 2 and Matlab version R2012 was used for method 3. For all methods, calculation of 95% confidence intervals (CIs) was performed using a normal approximation based on estimated standard errors. Findings During 2009-2011,367 notifiable measles cases occurred in Australia (mean annual rate: 5.5 cases per million population). Data were 100% complete for importation status but 77% complete for outbreak reference number. R was estimated as.< 1 for all years and data types, with values of0.65 (95% 0:0.60-0.70) obtained by method 1,0.64 (95% 0:0.56-0.72) by method 2 and 0.47 (95% 0:0.38-0.57) by method 3. Conclusion The fact that consistent estimates of R were obtained from all three methods enhances confidence in the validity of these methods for determining R. [TEXT NOT REPRODUCIBLE IN ASCII] Objectif Estimer le taux de reproduction efficace de la rougeole (R) en Australle en modelisant les donnees de notification de routine recueillies. Methodes R a ete estime pour la perlode 2009-2011 a l'aide de 3 methodes, en utlllsant les donnees du Systeme de Surveillance des Maladies a Declaration Obllgatolre de l'Australie. La methode 1 a estime que R est egal a 1-P, oli P est egal a la proportion de cas importes, tels que determines a partir des donnees obtenues sur le lieu de l'acquisltion. Les autres methodes ont estime R en ajustant un processus de ramification sous-critique qui modelise la propagation d'une infection avec un R donne pour les distributions observees de l'ampleur de l'epidemie (methode 2) et des generations de la propagation (methode 3). Le logiciel Stata version 12 a ete utilise pour la methode 2, et la logiciel Matlab version R2012 pour la methode 3. Pour toutes les methodes, le calcul des intervalles de confiance a 95% (1C) a ete effectue en utilisant une approximation normale basee sur les erreurs type estimees. Resultats Au cours de la periode 2009-2011, 367 cas de rougeole a declaration obligatoire ont ete enregistres en Australie (taux moyen annuel: 5,5 cas par million d'habitants). Les donnees etaient completes a 100% pour le statut de l'importation, mais completes a seulement 77% pour le numero de reference de l'epidemie. R a ete estime comme etant < 1 pour toutes les annees et tous les types de donnees, avec des valeurs de 0,65 (1C a 95%:0,60-0,70) obtenues par la methode 1, avec des valeurs de 0,64 (1C a 95%:0,56-0,72) par la methode 2 et avec des valeurs de 0,47 (1C a 95%:0,38-0,57) par la methode 3. Conclusion Le fait que des estimations coherentes de R ont ete obtenues a partir de ces 3 methodes renforce la confiance dans la validite de ces methodes pour la determination de R. [TEXT NOT REPRODUCIBLE IN ASCII] Objetivo Estimar el numero de reproduccion efectiva del sarampion (R) en Australia mediante el modelado de datos de notificaciones recopilados de forma rutinaria. Metodos Se estimo R para 2009-2011 a traves de tres metodos y con los datos del Sistema nacional de vigilancia epidemiologica de enfermedades de notificacion obligatoria de Australia. El metodo 1 estimo R como 1-P, donde P es igual a la proporcion de casos que fueron importados, segun lo determinado a partir de datos del lugar de adquisicion. El resto de metodos estimo R mediante la adaptacion de un proceso de ramificacion subcritico que modelaba la propagacion de una infeccion con un R dado a las distribuciones observadas de tamanos del brote (metodo 2) y a las generaciones de propagacion (metodo 3). Se empleo la version 12 de Stata para el metodo 2 y la version R2012 de Matlab para el metodo 3. Se realizo el calculo de Intervalos de confianza del 95 % (IC) para todos los metodos por medio de una aproximacion normal basada en errores estandar estimados. Resultados Durante 2009-2011, se dieron 367 casos de sarampion de declaracion obligatoria en Australia (tasa anual media: 5,5 casos por millon de habitantes). Los datos estaban completos al 100 % para el estado de importacion, pero al 77 % para el numero de referencia del brote. R se estimo como < 1 para todos los anos y tipos de datos, con valores de 0,65 (Cl del 95 %: 0,60-0,70) a traves del metodo 1,0,64 (IC del 95 %: 0,56-0,72) con el metodo 2 y 0,47 (IC del 95%: 0,38-0,57) con el metodo 3. Conclusion La obtencion de estimaciones consistentes de R mediante los tres metodos aumenta la confianza en la validez de estos metodos para determinar R., Abstracts in [TEXT NOT REPRODUCIBLE IN ASCII] and Espanol at the end of each article. Introduction Between 2000 and 2010, the global incidence of measles and the mortality caused by [...]

The 1998 Australian Measles Control Campaign had as its aim improved immunization coverage among children aged 1-12 years and, in the longer term, prevention of measles epidemics. The campaign included mass school-based measles-mumps-rubella vaccination of children aged 5-12 years and a catch-up programme for preschool children. More than 1.33 million children aged 5-12 years were vaccinated at school: serological monitoring showed that 94% of such children were protected after the campaign, whereas only 84% had been protected previously. Among preschool children aged 1-3.5 years the corresponding levels of protection were 89% and 82%. During the six months following the campaign there was a marked reduction in the number of measles cases among children in targeted age groups.

Elimination of endemic measles transmission is the culmination of a range of control measures at a national level. Current documentation of elimination proposed by WHO&apos;s regional offices requires achieving specific targets for surveillance process indicators. We demonstrate how Australia, although not meeting these specific targets, has satisfied multiple criteria that justify the formal declaration of measles elimination. Our review shows that few countries previously declaring measles elimination-have satisfied the current WHO surveillance targets. We argue that the requirements for recognition of measles elimination should not restrict countries to a particular type of surveillance system or surveillance criteria. L&apos;elimination de la transmission endemique de la rougeole est le point culminant d&apos;une serie de mesures de lutte contre cette maladie au niveau national. Pour attester de l&apos;elimination de la rougeole, les Bureaux regionaux de l&apos;OMS proposent actuellement que les indicateurs servant a la surveillance aient atteint des objectifs specifiques. Nous demontrons comment l&apos;Australie, bien que n&apos;ayant pas atteint ces objectifs, a rempli plusieurs criteres justifiant la declaration formelle de l&apos;elimination de la rougeole. Notre analyse montre que peu de pays ayant anterieurement declare la rougeole comme eliminee ont rempli les objectifs actuels en matiere de surveillance de l&apos;OMS. A notre avis, les exigences pour reconnaitre l&apos;elimination de la rougeole ne devraient pas imposer aux pays l&apos;utilisation d&apos;un type particulier de systeme ou de critere pour la surveillance. La eliminacion de la transmision endemica del sarampion supone la culminacion de toda una serie de medidas de control desplegadas a nivel nacional. La actual documentacion sobre la eliminacion propuesta por las oficinas regionales de la OMS requiere que se alcancen metas concretas para los indicadores del proceso de vigilancia. Explicamos aqui de que manera Australia, si bien no ha alcanzado esas metas especificas, ha satisfecho muchos criterios que justifican la declaracion oficial de eliminacion del sarampion. Nuestro analisis muestra que, entre los paises que han declarado haber eliminado esta enfermedad, son pocos los que han alcanzado las actuales metas de vigilancia de la OMS. Se argumenta que, entre los requisitos para el reconocimiento de la eliminacion del sarampion, no se debe exigir a los paises que apliquen solo un sistema de vigilancia o unos criterios de vigilancia determinados., Defining elimination Several WHO regions have set target dates for the elimination of the transmission of endemic measles. The WHO Regional Office for the Western Pacific (WPRO) has nominated the [...]

Objective: To model the impact of universal varicella vaccination in Australia. Methods: The results of an Australia-wide serosurvey for varicella zoster virus (VZV) immunity were used to parameterise realistic, age-structured deterministic models (RAS) developed by Brisson and colleagues. We examined the impact of a vaccination program for one-year-olds alone, and with a catch-up campaign for 11-year-olds, on the incidence of varicella and zoster, using Australia's population structure. Morbidity was then determined by calculating the number of hospital in-patient days. Results: Infant vaccination is predicted to reduce the incidence of varicella. However, zoster incidence is expected to increase initially, assuming exposure to varicella boosts immunity to zoster. Accumulated morbidity from both varicella and zoster is predicted to remain above that expected without vaccination for the first 70 years of an infant program (assuming 90% coverage with boosting for 20 years). However, after 70 years the net health savings from vaccination are predicted to increase substantially. Conclusions and Implications: Infant vaccination is expected to be a successful long-term commitment to reducing morbidity associated with VZV infection in Australia.

Objective: To measure immunity to poliovirus types 1, 2 and 3 in the Australian population. Methods: Sera were collected opportunistically from laboratories around Australia between 1996 and 1999. A representative sample by age and gender was tested for neutralising antibodies to poliovirus types 1, 2 and 3. A titre of [greater than or equal to]8 was considered antibody positive and indicative of immunity. Results: Of the 1,813 sera tested, 82% were antibody positive for poliovirus type 1 and 88% were positive for type 2. Immunity to type 3 poliovirus was lower overall (74%) and especially in school-aged children and young adults. For all three poliovirus types, there were more females immune than males and immunity peaked in the 2-4 years age group. The proportion of the population immune to all three types was 59%, and 3% were negative for all three types. Conclusions and Implications: This is the first national serosurvey for immunity to poliovirus in Australia. Herd immunity is probably sufficient to prevent generalised outbreaks due to type 1 and 2 poliovirus, but this may not be the case for type 3. However, localised outbreaks of any poliovirus type could still occur following reintroduction unless uniformly high levels of vaccination coverage are maintained. Ongoing serosurveillance is required following the recent change back to inactivated polio vaccine.

Objectives: To estimate the prevalence of chronic hepatitis B virus (HBV) infection in Australia and attributable proportions associated with specific demographic groups at higher risk of infection. Methods: Two methods were used to estimate prevalence of HBV surface antigen (HBsAg): (1) Population-based: results of a national serosurvey using sera collected opportunistically from laboratories across Australia were used for 1-59 year olds, with the HBsAg prevalence for 50-59 years extrapolated to the population aged 60 years and over; (2) Risk group-based: estimates for selected high-risk groups (injecting drug users, homosexual men, Indigenous Australians and people born in high-prevalence countries), using source data from antenatal HBV screening in central Sydney, HBV prevalence studies, and estimates for low-risk groups (first-time blood donors) were combined preportionally to their representation in the population. Results: Prevalence of HBsAg in the national serosurvey increased, with age, from 0.0% for 1-4 and 5-9 year olds to 1.3-1.8% for the 40-49 year age group. Australian population HBsAg prevalence based on minimum and adjusted estimates from this serosurvey were 91,500 (0.49%) and 163,000 (0.87%)infections, respectively. The risk group method estimated an Australian HBsAg prevalence of 88,000 infections (0.47%). Approximately 50% of people with chronic HBV infection were estimated to be immigrants from either South-East Asia (33.3%) or North-East Asia (16.2%). Conclusion: The range of estimates for chronic HBV infection in Australia is broad, reflecting the uncertainty in source data. A national blood survey encompassing a large and representative population sample may help to provide more accurate estimates A large proportion of people with chronic HBV infection are Asian born.