Impact of Rotavirus Vaccines on Gastroenteritis Hospitalizations in Western Australia: A Time-series Analysis.

BACKGROUND: Rotavirus vaccination was introduced into the Australian National Immunisation Program in mid-2007. We aimed to assess the impact of the rotavirus vaccination program on the burden of hospitalizations associated with all-cause acute gastroenteritis (including rotavirus gastroenteritis and non-rotavirus gastroenteritis) in the Aboriginal and non-Aboriginal population in Western Australia. METHODS: We identified all hospital records, between July 2004 and June 2012, with a discharge diagnosis code for all-cause gastroenteritis. Age-specific hospitalization rates for rotavirus and non-rotavirus acute gastroenteritis before and after the introduction of the rotavirus vaccination program were compared. Interrupted time-series models were used to examine differences in the annual trends of all-cause gastroenteritis hospitalization between the two periods. RESULTS: Between July 2004 and June 2012, there were a total of 106,974 all-cause gastroenteritis-coded hospitalizations (1,381 rotavirus-coded [15% among Aboriginal] and 105,593 non-rotavirus gastroenteritis-coded [7% among Aboriginal]). Following rotavirus vaccination introduction, significant reductions in rotavirus-coded hospitalization rates were observed in all children aged <5 years (up to 79% among non-Aboriginal and up to 66% among Aboriginal). Among adults aged ≥65 years, rotavirus-coded hospitalizations were 89% (95% confidence interval, 16-187%) higher in the rotavirus vaccination program period. The time-series analysis suggested reductions in all-cause gastroenteritis hospitalizations in the post-vaccination period among both vaccinated and unvaccinated (age-ineligible) children, with increases observed in adults aged ≥45 years. CONCLUSIONS: Rotavirus vaccination has been associated with a significant decline in gastroenteritis hospitalizations among children. The increase in the elderly requires further evaluation, including assessment of the cost-benefits of rotavirus vaccination in this population.

Antenatal care provider's advice is the key determinant of influenza vaccination uptake in pregnant women.

BACKGROUND: Although influenza vaccination is an important component of antenatal care and is recommended and funded by the Australian government, vaccination uptake has been low. AIMS: This study compared seasonal influenza vaccination uptake among pregnant Western Australian (WA) women and identified factors associated with vaccination uptake. MATERIALS AND METHODS: Adult women who were pregnant during the 2012 and 2013 influenza vaccination seasons were selected at random and invited to complete a computer-assisted telephone interview survey about whether they received influenza vaccination during pregnancy. Data analyses were weighted to the age distribution of women of reproductive age in WA. Multivariate logistic regression was used to identify factors associated with vaccination uptake. RESULTS: Between 2012 and 2013, the proportion of WA women whose antenatal care provider recommended influenza vaccination increased from 37.6 to 62.1% and vaccination uptake increased from 23.0 to 36.5%. The antenatal care provider's advice to have influenza vaccine was the single most important factor associated with vaccination (OR 11.1, 95% CI 7.9-15.5). Most women (63.7%) were vaccinated in general practice, 18.8% in a public hospital antenatal clinic and 11.0% at their workplace. Wanting to protect their infant from infection (91.2%) and having the vaccine recommended by their GP (60.0%) or obstetrician (51.0%) were commonly reported reasons for vaccination; worrying about side effects was a common reason for nonvaccination. CONCLUSIONS: To optimise maternal and infant health outcomes, Australian antenatal care providers and services need to incorporate both the recommendation and delivery of influenza vaccination into routine antenatal care.

Molecular characterisation of Cryptosporidium outbreaks in Western and South Australia.

Molecular typing at the 18S rRNA and Gp60 loci was conducted on Cryptosporidium-positive stool samples from cases collected during 2007 Western Australian and South Australian outbreaks of cryptosporidiosis. Analysis of 48 Western Australian samples identified that all isolates were C. hominis and were from five different Gp60C. hominis subtype families. The IbA10G2 subtype was most common across all age groups (37/48). In South Australia, analysis of 24 outbreak samples, identified 21 C. hominis isolates, two C. parvum isolates and one sample with both C. hominis and C. parvum. All C. hominis isolates were identified as the IbA10G2 subtype.

An outbreak of Salmonella enterica serotype Litchfield infection in Australia linked to consumption of contaminated papaya.

An outbreak of 26 cases of Salmonella Litchfield infection occurred in the states of Western Australia and Queensland between October 2006 and January 2007. A case-control study was conducted with 12 cases and 24 controls, and a significant association was found between illness and consumption of papaya (odds ratio, 32.8; 95% confidence interval, 2.71 to 883.5). Papaya samples were collected from 26 stores in Western Australia, and 9 of 38 samples were contaminated with Salmonella Litchfield. These samples had pulsed-field gel electrophoresis patterns and multilocus variable-number tandem-repeat analysis profiles indistinguishable from the outbreak strain. Three farms in Western Australia supplied the contaminated papaya, and two of these farms were inspected. Salmonella Litchfield was not detected in papaya samples, fungal sprays, or water samples from the farms; however, at one farm other serotypes of Salmonella were detected in untreated river water that was used for washing papaya. Only treated potable water should be used for washing fresh produce that is to be eaten raw.

Effectiveness of rotavirus vaccines in an Australian population: A case-control study.

OBJECTIVE: Two rotavirus vaccines (RV1 and RV5) were included in the publicly funded National Immunisation Program in Australia from July 2007. The programme in Western Australia initially provided RV1 (at ages 2 and 4 months) and then switched to RV5 (at ages 2, 4 and 6 months) from July 2009. This retrospective case-control study was conducted to assess the effectiveness of rotavirus vaccine against laboratory confirmed and notified cases of rotavirus infection among children aged <5 years. METHODS: Case-subjects were identified as vaccine-eligible children (born from 1 May 2007) who were notified as having rotavirus infection during the period 2009-2011. The control group was vaccine-eligible children notified as having Campylobacter or Salmonella infection during the same period. Individual rotavirus immunisation status was ascertained from a population-based immunisation register. Full-dose and partial-dose vaccine effectiveness (VE) were calculated for both vaccines using the adjusted odds ratio (OR) of vaccination for cases versus controls (VE = (1 - OR)*100%). RESULTS: Overall, 282 cases and 883 controls were included. The adjusted VE for a full course of either rotavirus vaccine was 72% (95% CI: 56-82) and 71% (95% CI: 50-84) for partial vaccination (one dose of RV1 or one/two doses of RV5). The VE for a complete 3-dose course of RV5 was 82% (95% CI: 59-92) and for a full 2-dose course of RV1 was 73% (95% CI: 55-83). CONCLUSIONS: RV1 and RV5 were both effective in preventing laboratory confirmed and notified rotavirus infections among children aged <5 years. Even incomplete courses of vaccination conferred good protection.

Estimating influenza vaccine effectiveness using data routinely available in electronic primary care records.

BACKGROUND: To support timely, annual estimation of influenza vaccine effectiveness (VE), we explored the use of automated data extraction from general practice records to estimate VE over four consecutive southern hemisphere influenza seasons. METHODS: A software tool installed at 130 practices in Western Australia identified all outpatients tested for influenza by polymerase-chain-reaction (PCR) during annual influenza seasons occurring 2012-2015. Laboratory test results were collated with any existing record of influenza vaccine administered in the same year; limited patient demographic and clinical information was also collected. A case test-negative control analysis compared the odds of seasonal influenza vaccination between patients positive or negative for influenza by PCR with VE = 1 - the odds ratio. RESULTS: A total of 7270 influenza PCR test results were identified of which 1907 (26.2%) were positive; 9.4% of patients with a positive result had received contemporaneous influenza vaccination ≥14 days prior to specimen collection, compared to 17.9% of those with a negative result. Overall VE was 52% (95% CI, 43-60%); annual VE estimates ranged from 46% (95% CI, 22-63%) in 2012 to 60% (95% CI, 41-73%) in 2014. CONCLUSION: Electronic records routinely maintained by general practice provide a promising opportunity for estimating annual influenza VE in a timely and resource-efficient manner.

An audit of the reliability of influenza vaccination and medical information extracted from eHealth records in general practice.

To evaluate the reliability of information in general practice (GP) electronic health records (EHRs), 2100 adult patients were randomly selected for interview regarding the presence of specific medical conditions and recent influenza vaccination. Agreement between self-report and data extracted from EHRs was compared using Cohen's kappa coefficient (k) and interpreted in accordance with Altman's Kappa Benchmarking criteria; 377 (18%) patients declined participation, and 608 (29%) could not be contacted. Of 1115 (53%) remaining, 856 (77%) were active patients (≥3 visits to the GP practice in the last two years) who provided complete information for analysis. Although a higher proportion of patients self-reported being vaccinated or having a medical condition compared to the EHR (50.7% vs 36.9%, and 39.4% vs 30.3%, respectively), there was "good" agreement between self-report and EHR for both vaccination status (κ = 0.67) and medical conditions (κ = 0.66). These findings suggest EHR may be useful for public health surveillance.

Pretravel Health Advice Among Australians Returning From Bali, Indonesia: A Randomized Controlled Trial Protocol.

BACKGROUND: The effect of pretravel health advice (PTHA) on travel-related illness rates is poorly understood, and to date there are no published randomized controlled trials evaluating the impact of PTHA outcomes. OBJECTIVE: This study aims to determine the effect of an online PTHA intervention on travel-related illness rates in Western Australians visiting Bali, Indonesia. METHODS: Western Australian travelers to Bali will be recruited online before departure and will be randomly allocated to an intervention or control group by computer algorithm. The intervention in this study is a short animated video, with accompanying text, containing PTHA relevant to Bali. An online posttravel survey will be administered to all participants within two weeks of their return from Bali. The primary outcome is the difference in self-reported travel-related illness rates between control and intervention groups. Secondary outcomes include the difference in risk prevention behaviors and health risk knowledge between the control and intervention groups. Further secondary outcomes include whether individuals in the control group who sought external PTHA differ from those who did not with respect to risk prevention behaviors, health risk knowledge, and health risk perception, as well as the rate of self-reported travel-related illness. RESULTS: The study began recruitment in September 2016 and will conclude in September 2017. Data analysis will take place in late 2017, with results disseminated via peer-reviewed journals in early 2018. CONCLUSIONS: This will be the first randomized controlled trial to examine the effect of a novel PTHA intervention upon travel-related illness. In addition, this study builds upon the limited existing data on the effectiveness of PTHA on travel-related illness. CLINICALTRIAL: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12615001230549; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=369567 (Archived by WebCite at http://www.webcitation.org/6m0G7xJg1).

Health Seeking Behaviours and Knowledge of Infectious Disease Risks in Western Australian Travellers to Southeast Asian Destinations: An Airport Survey.

As the number of Australians engaging in short-term international travel increases, so does the opportunity for importing overseas-acquired infectious diseases. This study aimed to determine knowledge of infectious disease risks and pre-travel health advice (PTHA) seeking behaviour among Western Australians travelling to Bali, Indonesia or Thailand. Passengers departing from Perth International Airport were invited to participate in a self-administered survey. The survey determined PTHA seeking behaviour, knowledge of specific disease risks, and expected disease-prevention behaviours abroad. Multivariate regression modelling was used to assess demographic and travel-related factors associated with seeking PTHA. Responses from 1334 travellers were analysed. The proportion correctly identifying specific overseas disease risks ranged from 27% to 98%. High levels of planned disease-preventive behaviours were reported; however only 32% of respondents sought PTHA for their trip, most commonly from friends/family (15%) or a GP (14%). Many travellers (87%) made online travel purchases, but few (8%) used the Internet to source PTHA. WA travellers to Bali and Thailand were unlikely to seek PTHA and knowledge varied regarding infectious disease risks associated with travel. High rates of internet use when planning travel may provide an opportunity for destination-specific health promotion messaging and should be explored.

Trends in seasonal influenza vaccine uptake during pregnancy in Western Australia: Implications for midwives.

BACKGROUND: Antenatal influenza vaccination is an important public health intervention for preventing serious illness in mothers and newborns, yet uptake remains low. AIM: To evaluate trends in seasonal influenza vaccine coverage and identify determinants for vaccination among pregnant women in Western Australia. METHODS: We conducted an annual telephone survey in a random sample of post-partum women who delivered a baby in Western Australia between 2012 and 2014. Women were asked whether influenza vaccination was recommended and/or received during their most recent pregnancy; women were also asked why or why they were not immunised. FINDINGS: Between 2012 and 2014, influenza vaccine coverage increased from 22.9% to 41.4%. Women who reported receiving the majority of their antenatal care from a private obstetrician were significantly more likely to have influenza vaccination recommended to them than those receiving the majority of their care from a public antenatal hospital or general practitioner (p<0.001). In 2014, the most common reason women reported for accepting influenza vaccination was to protect the baby (92.8%) and the most common reason for being unimmunised was lack of a healthcare provider recommendation (48.5%). DISCUSSION: Antenatal influenza vaccination uptake is increasing, but coverage remains below 50%. A recommendation from the principal care provider is an important predictor of maternal influenza vaccination. CONCLUSION: Antenatal care providers, including midwives, have a key role in providing appropriate information and evidence-based recommendations to pregnant women to ensure they are making informed decisions. Consistent recommendations from antenatal care providers are critical to improving influenza vaccine coverage in pregnant women.

Post-marketing surveillance of adverse events following immunization with inactivated quadrivalent and trivalent influenza vaccine in health care providers in Western Australia.

In 2015, inactivated quadrivalent influenza vaccine (QIV) was first introduced into the Australian market. A routine vaccine safety surveillance system in Western Australia was used to conduct post-licensure surveillance of adverse events following immunization with inactivated QIV and trivalent influenza vaccines (TIV) in a sample of 1685 healthcare providers (HCPs). A similar percentage of HCPs who received QIV reported having any reaction seven days post-vaccination as HCPs who received TIV (13.6 vs. 12.8%, respectively; p=0.66). However, a slightly higher percentage of HCPs who received QIV reported pain or swelling at the injection site as compared to HCPs who received TIV (6.9% vs. 4.2%, respectively; p=0.02). No serious vaccine-associated adverse events were detected during follow-up of either vaccine. Acknowledging the study limitations, the results of this post-marketing surveillance support the safety of QIV, suggesting there is little difference in the reactogenicity of QIV as compared to TIV.

The impact of parental postpartum pertussis vaccination on infection in infants: A population-based study of cocooning in Western Australia.

During a pertussis epidemic in 2011-2012 the Western Australian (WA) Department of Health implemented a 'cocooning' programme, offering free pertussis-containing vaccine (dTpa) to new parents. We assessed the impact of vaccinating parents with dTpa on the incidence of pertussis infection in newborns. Births in WA during 2011-2012 were linked to a register of parental pertussis vaccinations and to notified reports of laboratory-proven pertussis in children <6 months of age. Parents who received dTpa during the four weeks after their child's birth were defined as 'vaccinated postpartum.' Cox proportional-hazards methods were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of pertussis infection among infants born to parents vaccinated postpartum vs. unvaccinated parents, adjusted for maternal age, geographic region, timing of birth, and number of siblings. Of 64,364 live-births, 43,480 (68%) infants had at least one vaccinated parent (60% of mothers and 36% of fathers). After excluding records where parent(s) were either vaccinated prior to the birth, vaccinated >28 days after the birth, the vaccination date was uncertain, or the child died at birth (n=42), the final cohort contained 53,149 children, 118 of whom developed pertussis. There was no difference in the incidence of pertussis among infants whose parents were both vaccinated postpartum compared to those with unvaccinated parents (1.9 vs 2.2 infections per 1000 infants; adjusted HR 0.91; 95%CI 0.55-1.53). Similarly, when assessed independently, maternal postpartum vaccination was not protective (adjusted HR 1.19; 95%CI 0.82-1.72). Supplemental sensitivity analyses which varied the time period for parental vaccination and accounted for under-reporting of vaccination status did not significantly alter these findings. In our setting, vaccinating parents with dTpa during the four weeks following delivery did not reduce pertussis diagnoses in infants. WA now provides dTpa vaccine to pregnant women during the third trimester.

Respiratory outcomes in high-risk children 7 to 10 years after prophylaxis with respiratory syncytial virus immune globulin.

PURPOSE: Respiratory syncytial virus infections have been implicated in the development of asthma. We evaluated the long-term effects of respiratory syncytial virus immune globulin, an effective prophylactic agent for the prevention of these infections in children, on respiratory and allergic outcomes in children at high risk of chronic airway disease. SUBJECTS AND METHODS: Thirteen children at high risk of respiratory disease (mean [+/-SD] age, 8.6 +/- 1.1 years) were evaluated using pulmonary function and allergy skin testing 7 to 10 years after they had received prophylaxis with respiratory syncytial virus immune globulin. For comparison, 26 high-risk control children (mean age, 8.5 +/- 0.9 years) were also evaluated. Health outcomes data were collected from all subjects. The children were matched for age and gestational age. There were more boys, and a lesser frequency of a lower respiratory tract infection with respiratory syncytial virus (P <0.001) in the group that had been treated prophylactically than in the controls. The ratio of the forced expiratory volume in 1 second to forced vital capacity was significantly better in children who had received immune globulin (median, 0.88; interquartile range, 0.81 to 0.91) than in the controls (median, 0.76; interquartile range, 0.67 to 0.86; P = 0.02). Children were also less atopic (2 of 13) in the respiratory syncytial virus immune globulin group than in the control group (13 of 26, P <0.04) and were less likely to have missed school (P = 0.006) or have had an asthma attack (P = 0.03). CONCLUSION: The results suggest that prophylaxis of respiratory syncytial virus infections in infancy may have long-term effects on respiratory and immunologic parameters relevant to the development of asthma. Larger-scale studies are needed.