Estimated health and economic impact of using high-dose influenza vaccine on respiratory and circulatory plus respiratory hospitalizations of older adults in Australia.

Background: Standard dose influenza vaccine provides moderate protection from infection, but with lower effectiveness among the elderly. High dose and adjuvanted vaccines (HD-TIV and aTIV) were developed to address this. This study aims to estimate the incremental health and economic impact of using HD-TIV (high dose trivalent vaccine) instead of aTIV (adjuvanted trivalent vaccine) on respiratory and circulatory plus respiratory hospitalizations of older people (≥65 years) in Australia. Methods: This is a modelling study comparing predicted hospitalization outcomes in people receiving HD-TIV or aTIV during an average influenza season in Australia. Hospitalization records of Australian adults ≥65 years of age from 01 April to 30 November during 15 influenza seasons (2002-2017 excluding 2009, which was a pandemic) were extracted from the Australian Institute of Health and Welfare [AIHW] and used to calculate hospitalisation rates during an average season. Relative vaccine effectiveness data for aTIV and HD-TIV were used to estimate morbidity burden related to influenza. Results: Between 2002 and 2017, the average respiratory hospitalization rate among older people during influenza season (April-November) was 3,445/100,000 population-seasons, with an average cost of AU$ 7,175 per admission. The average circulatory plus respiratory hospitalization rate among older Australian people during that time was 10,393/100,000 population-seasons, with an average cost of AU$ 7829 per admission. For older Australians, HD-TIV may avert an additional 6,315-9,410 respiratory admissions each year, with an incremental healthcare cost saving of AU$ 15.9-38.2 million per year compared to aTIV. Similar results were also noted for circulatory plus respiratory hospitalizations. Conclusions: From the modelled estimations, HD-TIV was associated with less economic burden and fewer respiratory, and circulatory plus respiratory hospitalizations than aTIV for older Australians.

The impact of COVID-19 and COVID vaccination on cardiovascular outcomes.

COVID-19 is an independent risk factor for cardiovascular disease. COVID-19 vaccination may prevent this, but in some cases, COVID-19 vaccination may cause myocarditis or pericarditis. Patients with COVID-19 may present with non-specific symptoms that have a cardiac origin. This review examines the cardiovascular complications of COVID-19 infection and the impact of COVID-19 vaccination. COVID-19 cardiovascular complications include myocardial injury, pericarditis, coagulopathy, myocardial infarction, heart failure, arrhythmias, and persistent post-acute risk of adverse cardiovascular outcomes. Diagnostic and referral pathways for non-specific symptoms, such as dyspnoea and fatigue, remain unclear. COVID-19 vaccination is cardioprotective overall but is associated with myopericarditis in young males, though at a lower rate than following SARS-CoV-2 infection. Increased awareness among primary care physicians of potential cardiovascular causes of non-specific post-COVID-19 symptoms, including in younger adults, such as fatigue, dyspnoea, and chest pain, is essential. We recommend full vaccination with scheduled booster doses, optimal management of cardiovascular risk factors, rapid treatment of COVID-19, and clear diagnostic, referral, and management pathways for patients presenting with non-specific symptoms to rule out cardiac complications.

Effectiveness estimates for enhanced trivalent influenza vaccines in an aged care summer outbreak.

An influenza outbreak occurred during summer (February 2019) in an aged-care facility in Sydney, Australia. Residents had not received the annual 2019 influenza vaccine while 76.7% had received 2018 influenza vaccines about 9 months prior. Overall, 2018 influenza vaccine effectiveness during this outbreak was high (93.6%). The effectiveness of the high-dose trivalent vaccine (HD-TIV) and adjuvanted trivalent (a-TIV) vaccine were 89.8% (95% confidence interval: 18.8%-98.7%) and 72.5% (95% confidence interval: -106.7%-96.3%) respectively. The differences in effectiveness between HD-TIV, a-TIV and SD-QIV, during the summer outbreak were not significant.

Predictors of herpes zoster vaccination among Australian adults aged 65 and over.

OBJECTIVE(S): To estimate HZ vaccine coverage in Australia among older Australians and to identify potential barriers to vaccination. DESIGN: Analysis of data from three cross-sectional surveys administered online between 2019 and 2020. SETTING AND PARTICIPANTS: Adults aged 65 and over residing in Australia. MAIN OUTCOME MEASURES: Self-reported herpes zoster vaccination. RESULTS: Among the 744 adults aged 65 and over in this sample, 32% reported being vaccinated for HZ, including 23% of participants aged 65-74, 55% of participants aged 75-84, and 0% for participants aged 85 and above. Those who are vaccinated with other immunisations are more likely to have received HZ vaccine, including seasonal influenza (OR = 4.41, 95 % CI: 2.44-7.98) and pneumococcal vaccines (OR = 4.43, 95 % CI: 2.92 - 6.75). Participants with a history of certain conditions, such as stroke (OR = 2.26, 95 % CI: 1.13-4.49), were more likely to be vaccinated against HZ. Participants that reported smoking tobacco daily were less likely to be vaccinated against HZ (OR = 0.48, 95 % CI: 0.26-0.89). Participants were less likely to be vaccinated against HZ if they preferred to develop immunity 'naturally' (OR = 0.29, 95 % CI: 0.15 - 0.57) or expressed distrust of vaccines (OR = 0.34, 95 % CI: 0.13-0.91). CONCLUSION(S): Further research is required to understand the barriers to HZ vaccine uptake. Increasing the funding eligibility for those who are at risk of complications from shingles, or lowering the age of eligibility, may increase vaccine coverage.

Cross-sectional survey of changes in knowledge, attitudes and practice of mask use in Sydney and Melbourne during the 2020 COVID-19 pandemic.

OBJECTIVES: Since mask uptake and the timing of mask use has the potential to influence the control of the COVID-19 pandemic, this study aimed to assess the changes in knowledge toward mask use in Sydney and Melbourne, Australia, during the 2020 COVID-19 pandemic. DESIGN: An observational study, using a cross-sectional survey, was distributed to adults in Sydney and Melbourne, Australia, during July-August 2020 (survey 1) and September 2020 (survey 2), during the COVID-19 pandemic in Australia. SETTING AND PARTICIPANTS: Participants aged 18 years or older and living in either Sydney or Melbourne. PRIMARY AND SECONDARY OUTCOME MEASURES: Demographics, risk measures, COVID-19 severity and perception, mask attitude and uptake were determined in this study. RESULTS: A total of 700 participants completed the survey. In both Sydney and Melbourne, a consistent decrease was reported in almost all risk-mitigation behaviours between March 2020 and July 2020 and again between March 2020 and September 2020. However, mask use and personal protective equipment use increased in both Sydney and Melbourne from March 2020 to September 2020. There was no significant difference in mask use during the pandemic between the two cities across both timepoints (1.24 (95% CI 0.99 to 1.22; p=0.072)). Perceived severity and perceived susceptibility of COVID-19 infection were significantly associated with mask uptake. Trust in information on COVID-19 from both national (1.77 (95% CI 1.29 to 2.44); p<0.000)) and state (1.62 (95% CI 1.19 to 2.22); p=0.003)) government was a predictor of mask use across both surveys. CONCLUSION: Sydney and Melbourne both had high levels of reported mask wearing during July 2020 and September 2020, consistent with the second wave and mask mandates in Victoria, and cluster outbreaks in Sydney at the time. High rates of mask compliance may be explained by high trust levels in information from national and state government, mask mandates, risk perceptions, current outbreaks and the perceived level of risk of COVID-19 infection at the time.

Predictors of pneumococcal vaccination among Australian adults at high risk of pneumococcal disease.

BACKGROUND: Although nearly all Australian children are vaccinated against pneumococcal disease, pneumococcal vaccine uptake is low among high-risk adults. This study aimed to identify perceived barriers to pneumococcal vaccination among high-risk adults. METHODS: This paper reports combined data on pneumococcal vaccination collected from three different online, cross-sectional surveys that were administered in Australia between August 2019 and September 2020. Using Poisson regression, we identified characteristics and beliefs associated with self-reported pneumococcal vaccination among adults aged 65 and over or with chronic health conditions. RESULTS: The weighted estimate for pneumococcal vaccine coverage was 24% for high-risk adults under 65 and 53% for adults aged 65 and over. Nearly half of those under 65 reported they had never heard of the pneumococcal vaccine, while 26% of those aged 65 and over had never heard of the vaccine. Among those under 65, pneumococcal vaccination was associated with high perceived disease susceptibility (PR = 1.97, 95% CI: 1.23, 3.18), not having heard of the pneumococcal vaccine (PR = 0.44, 95% CI: 0.28-0.69), awareness that their chronic health condition puts them at increased risk of pneumonia (PR = 2.44, 95% CI: 1.51-3.98), and having a doctor recommend the vaccine (PR = 3.02, 95% CI: 2.05-4.44). Among adults aged 65 and over, self-reported pneumococcal vaccination was associated with influenza vaccination in the previous 12 months (PR = 4.28, 95% CI: 2.85-6.44) and awareness that they are eligible for free pneumococcal vaccination (PR = 5.02, 95% CI: 2.34-10.77). CONCLUSION: Awareness of pneumococcal vaccines was low among adults at high risk of pneumococcal disease, which appears to be contributing to low vaccine uptake. A doctor's recommendation was associated with increased uptake of pneumococcal vaccine, so interventions should be developed to promote pneumococcal vaccine uptake in GP practices.

Trust in government, intention to vaccinate and COVID-19 vaccine hesitancy: A comparative survey of five large cities in the United States, United Kingdom, and Australia.

BACKGROUND: There is widespread hesitancy towards COVID-19 vaccines in the United States, United Kingdom, and Australia. OBJECTIVE: To identify predictors of willingness to vaccinate against COVID-19 in five cities with varying COVID-19 incidence in the US, UK, and Australia. DESIGN: Online, cross-sectional survey of adults from Dynata's research panel in July-September 2020. PARTICIPANTS, SETTING: Adults aged 18 and over in Sydney, Melbourne, London, New York City, or Phoenix. MAIN OUTCOMES AND MEASURES: Willingness to receive a COVID-19 vaccine; reason for vaccine intention. STATISTICAL METHODS: To identify predictors of intention to receive a COVID-19 vaccine, we used Poisson regression with robust error estimation to produce prevalence ratios. RESULTS: The proportion willing to receive a COVID-19 vaccine was 70% in London, 71% NYC, 72% in Sydney, 76% in Phoenix, and 78% in Melbourne. Age was the only sociodemographic characteristic that predicted willingness to receive a COVID-19 vaccine in all five cities. In Sydney and Melbourne, participants with high confidence in their current government had greater willingness to receive the vaccine (PR = 1.24; 95% CI = 1.07-1.44 and PR = 1.38; 95% CI = 1.74-1.62), while participants with high confidence in their current government in NYC and Phoenix were less likely to be willing to receive the vaccine (PR = 0.78; 95% CI = 0.72-0.85 and PR = 0.85; 95% CI = 0.76-0.96). LIMITATIONS: Consumer panels can be subject to bias and may not be representative of the general population. CONCLUSIONS: Success for COVID-19 vaccination programs requires high levels of vaccine acceptance. Our data suggests more than 25% of adults may not be willing to receive a COVID-19 vaccine, but many of them were not explicitly anti-vaccination and thus may become more willing to vaccinate over time. Among the three countries surveyed, there appears to be cultural differences, political influences, and differing experiences with COVID-19 that may affect willingness to receive a COVID-19 vaccine.

Modelling of COVID-19 vaccination strategies and herd immunity, in scenarios of limited and full vaccine supply in NSW, Australia.

Several vaccines for SARS-CoV-2 are expected to be available in Australia in 2021. Initial supply is limited and will require a judicious vaccination strategy until supply is unrestricted. If vaccines have efficacy as post-exposure prophylaxis (PEP) in contacts, this provides more policy options. We used a deterministic mathematical model of epidemic response with limited supply (age-targeted or ring vaccination) and mass vaccination for the State of New South Wales (NSW) in Australia. For targeted vaccination, the effectiveness of vaccinating health workers, young people and older adults was compared. For mass vaccination, we tested varying vaccine efficacy (VE) and distribution capacities. With a limited vaccine stockpile enough for 1 million people in NSW, if there is efficacy as PEP, the most efficient way to control COVID-19 will be ring vaccination, however at least 90% of contacts per case needs to be traced and vaccinated. Health worker vaccination is required for health system resilience. Age based strategies with restricted doses make minimal impact on the epidemic, but vaccinating older people prevents more deaths. Herd immunity can only be achieved with mass vaccination. With 90% VE against all infection, herd immunity can be achieved by vaccinating 66% of the population. A vaccine with less than 70% VE cannot achieve herd immunity and will result in ongoing risk of outbreaks. For mass vaccination, distributing at least 60,000 doses per day is required to achieve control. Slower rates of vaccination will result in the population living with COVID-19 longer, and higher cases and deaths.

Pacific Eclipse - A tabletop exercise on smallpox pandemic response.

BACKGROUND: In December 2019, we ran Pacific Eclipse, a pandemic tabletop exercise using smallpox originating in Fiji as a case study. Pacific Eclipse brought together international stakeholders from health, defence, law enforcement, emergency management and a range of other organisations. AIM: To review potential gaps in preparedness and identify modifiable factors which could prevent a pandemic or mitigate the impact of a pandemic. METHODS: Pacific Eclipse was held on December 9-10 in Washington DC, Phoenix and Honolulu simultaneously. The scenario began in Fiji and becomes a pandemic. Mathematical modelling of smallpox transmission was used to simulate the epidemic under different conditions and to test the effect of interventions. Live polling, using Poll Everywhere software that participants downloaded onto their smart phones, was used to gather participant decisions as the scenario unfolded. Stakeholders from state and federal government and non-government organisations from The United States, The United Kingdom, Australia, New Zealand, Canada, as well as industry and non-government organisations attended. RESULTS: The scenario progressed in three phases and participants were able to make decisions during each phase using live polling. The polling showed very diverse and sometimes conflicting decision making. Factors influential to pandemic severity were identified and categorised as modifiable or unmodifiable. A series of recommendations were made on the modifiable determinants of pandemic severity and how these can be incorporated into pandemic planning. These included preventing an attack through intelligence, law enforcement and legislation, improved speed of diagnosis, speed and completeness of case finding and case isolation, speed and security of vaccination response (including stockpiling), speed and completeness of contact tracing, protecting critical infrastructure and business continuity, non-pharmaceutical interventions (social distancing, PPE, border control) and protecting first responders. DISCUSSION: Pacific Eclipse illustrated the impact of a pandemic of smallpox under different response scenarios, which were validated to some extent by the COVID-19 pandemic. The framework developed from the scenario draws out modifiable determinants of pandemic severity which can inform pandemic planning for the ongoing COVID-19 pandemic and for future pandemics.

Pharmacy, workplace or primary care? Where Australian adults get their influenza vaccines.

OBJECTIVE: To estimate the proportion of influenza vaccines administered in non-medical settings in Australia in 2019 and identify factors associated with vaccination site. METHODS: We surveyed 1,444 Australian adults online in October 2019. To identify factors associated with vaccination site, we used Pearson's chi-square test. We used thematic analysis to describe responses to the question, 'Please explain why you chose to get vaccinated there'. RESULTS: Most participants (73%) received the influenza vaccine in a medical setting, while 13% received it at a pharmacy and 14% at their workplace. Being vaccinated in pharmacy was associated with being under 65 years of age (p<0.01), marital status (p=0.01), and not having a high-risk comorbidity (p<0.01). Workplace vaccination was associated with being under 65 (p<0.01), household income (p<0.01), not having a regular general physician/practice (p=0.01), having private insurance (p<0.01), and not having a high-risk comorbidity (p<0.01). There was no association between site of vaccination and first-time vaccination (p=0.71, p=0.22). CONCLUSIONS: Despite new policies allowing pharmacists to administer influenza vaccines, most Australian adults are still vaccinated in medical settings. Pharmacy and workplace vaccination settings were more common among younger adults without high-risk comorbidities. Implications for public health: Workplaces, pharmacies and other non-medical settings may provide an opportunity to increase influenza vaccination among healthy, working-age adults who might otherwise forego annual vaccination. Pharmacies may also provide a convenient location for the rollout of the COVID-19 vaccine, particularly in medically underserved areas.

Mask use, risk-mitigation behaviours and pandemic fatigue during the COVID-19 pandemic in five cities in Australia, the UK and USA: A cross-sectional survey.

OBJECTIVES: To determine patterns of mask wearing and other infection prevention behaviours, over two time periods of the COVID-19 pandemic, in cities where mask wearing was not a cultural norm. METHODS: A cross-sectional survey of masks and other preventive behaviours in adults aged ≥18 years was conducted in five cities: Sydney and Melbourne, Australia; London, UK; and Phoenix and New York, USA. Data were analysed according to the epidemiology of COVID-19, mask mandates and a range of predictors of mask wearing. RESULTS: The most common measures used were avoiding public areas (80.4%), hand hygiene (76.4%), wearing masks (71.8%) and distancing (67.6%). Over 40% of people avoided medical facilities. These measures decreased from March-July 2020. Pandemic fatigue was associated with younger age, low perceived severity of COVID-19 and declining COVID-19 prevalence. Predictors of mask wearing were location (US, UK), mandates, age <50 years, education, having symptoms and knowing someone with COVID-19. Negative experiences with mask wearing and low perceived severity of COVID-19 reduced mask wearing. Most respondents (98%) believed that hand washing and distancing were necessary, and 80% reported no change or stricter adherence to these measures when wearing masks. CONCLUSION: Pandemic mitigation measures were widely reported across all cities, but decreased between March and July 2020. Pandemic fatigue was more common in younger people. Cities with mandates had higher rates of mask wearing. Promotion of mask use for older people may be useful. Masks did not result in a reduction of other hygiene measures.

Using the health belief model to identify barriers to seasonal influenza vaccination among Australian adults in 2019.

BACKGROUND: Each year tens of thousands of Australians become ill with influenza, resulting in thousands of severe infections that require hospitalisation. However, only 40% of adults receive the annual influenza vaccine. We surveyed Australian adults to provide up to date, population-specific data on the predictors and barriers of seasonal influenza vaccination. METHODS: We administered an online survey to a nationally representative sample of Australian adults. We designed survey questions using the theoretical constructs of the health belief model. Using simple and multivariable Poisson regression, we identified attitudes and beliefs associated with influenza vaccination in 2019. RESULTS: Among 1,444 respondents, 51.7% self-reported influenza vaccination in 2019. We estimated vaccine coverage to be 44% for adults under 45, 46% for adults aged 45 to 64 and 77% for adults aged 65 and over. The strongest individual predictors of self-reported vaccination were believing the vaccine is effective at preventing influenza (APR = 3.71; 95% CI = 2.87-4.80), followed by recalling their doctor recommending the vaccine (APR = 2.70; 95% CI = 2.31-3.16). Common perceived barriers that predicted self-reported vaccination included believing the vaccine could give you influenza (APR = 0.59; 95% CI = 0.52-0.67), believing the vaccine can make you ill afterwards (APR = 0.68; 95% CI = 0.62-0.74) and preferring to develop immunity "naturally" (APR = 0.38; 95% CI = 0.32-0.45). CONCLUSION: Although vaccine uptake in 2019 appears to be higher than previous years, there are perceived barriers which may limit uptake among Australians. Tailored interventions are needed to combat widespread influenza vaccine hesitancy, particularly among high-risk groups.

Epidemiology of 2017 influenza outbreaks in nine Australian Aged care facilities.

BACKGROUND: The 2017 A/H3N2 influenza season was the most severe season since the 2009 influenza pandemic. There were over 591 influenza outbreaks in institutions across the state of New South Wales (NSW) in Australia. AIM: To describe the epidemiology of influenza outbreaks in nine Sydney aged care facilities in 2017. METHODS: Study data were collected from nine Sydney aged care facilities for 2017 influenza season. Descriptive epidemiological analysis was conducted. RESULTS: From the nine sites included, with a total of 716 residents, four sites reported laboratory-confirmed influenza outbreaks during the study period, with an attack rate in residents ranging from 6% to 29%. The outbreaks resulted in lockdowns in two facilities and hospitalisation of seven residents. No deaths were reported as a result of influenza infection. Influenza A was the most common influenza type reported across the facilities. The duration of outbreak lasted for 1-4 weeks varied by site. CONCLUSION: The 2017 season was a severe influenza season recorded in Australia. About half of the facilities studied experienced outbreaks of influenza, with a high attack rate among residents. Infection prevention and control measures and outbreak management plans are crucial for aged care facilities, including vaccination of staff and visitors to prevent outbreaks among the vulnerable residents.

Serological Immunity to Smallpox in New South Wales, Australia.

The re-emergence of smallpox is an increasing and legitimate concern due to advances in synthetic biology. Vaccination programs against smallpox using the vaccinia virus vaccine ceased with the eradication of smallpox and, unlike many other countries, Australia did not use mass vaccinations. However, vaccinated migrants contribute to population immunity. Testing for vaccinia antibodies is not routinely performed in Australia, and few opportunities exist to estimate the level of residual population immunity against smallpox. Serological data on population immunity in Australia could inform management plans against a smallpox outbreak. Vaccinia antibodies were measured in 2003 in regular plasmapheresis donors at the Australian Red Cross Blood Service from New South Wales (NSW). The data were analysed to estimate the proportion of Australians in NSW with detectable serological immunity to vaccinia. The primary object of this study was to measure neutralising antibody titres against vaccinia virus. Titre levels in donor samples were determined by plaque reduction assay. To estimate current levels of immunity to smallpox infection, the decline in geometric mean titres (GMT) over time was projected using two values for the antibody levels estimated on the basis of different times since vaccination. The results of this study suggest that there is minimal residual immunity to the vaccinia virus in the Australian population. Although humoral immunity is protective against orthopoxvirus infections, cell-mediated immunity and immunological memory likely also play roles, which are not quantified by antibody levels. These data provide an immunological snapshot of the NSW population, which could inform emergency preparedness planning and outbreak control, especially concerning the stockpiling of vaccinia vaccine.

Influenza vaccine coverage and predictors of vaccination among aged care workers in Sydney Australia.

Aged care facilities (ACFs) are residential communities with a concentration of vulnerable individuals with increased risk of severe influenza infection and complications such as outbreaks, hospitalisations and deaths. Aged care workers (ACW) are potential sources of influenza introduction and transmission in ACFs. Little is known about vaccine uptake among ACW. This study aimed to measure the vaccine uptake rate among Australian ACW and evaluate the demographic determinants of uptake during the influenza season of 2018. 146 ACWs were recruited from 7 facilities of a multisite aged care provider in Sydney. ACWs completed a questionnaire regarding their demographic, occupational and vaccination status. Vaccine coverage was calculated and variables were examined against their 2018 influenza vaccination status in statistical analysis. ACWs in our study were predominantly from a non-health occupational background with a large proportion of migrant workers (56%, 75/134). Vaccine coverage in 2018 was 48% (65/135). The strongest determinants of vaccine uptake were previous year vaccination history (Odds Ratio [OR] 10.49, 95% CI 3.33-33.10), workplace immunisation programs for employees (OR 7.87, 95% CI 2.47-25.10), casual work as employment status (OR 0.14, 95% CI 0.02-0.77), and presence of comorbidities (OR 4.04, 95% CI 1.23-13.32). ACW are a unique and understudied group who are critical to infection control in ACFs. Few ACWs have formal health training, and many are migrants who may lack access to subsidised health care and face out of pocket costs for vaccination. Vaccine coverage among ACW were below recommended levels. Provision of influenza vaccine for staff in workplaces is highly effective in raising vaccine coverage amongst ACWs. More research on the aged care sector workforce is needed in order to evaluate the determinants of vaccine uptake among Australian ACWs.

Modelling of optimal timing for influenza vaccination as a function of intraseasonal waning of immunity and vaccine coverage.

The influenza season in Australia usually peaks in August. Vaccination is recommended beginning in March-April. Recent studies suggest that vaccine effectiveness may wane over a given influenza season, leading to reduced effectiveness at the peak of the season. We aimed to quantify how changes in timing of influenza vaccination and declining vaccine coverage could change the percentages of prevented cases. Results from a systematic review were used to inform calculation of a waning function over time from vaccination. Age specific notification data and vaccine effectiveness and coverage estimates from 2007 to 2016 (2009 influenza pandemic year excluded) were used to model a new notification series where vaccine effectiveness is shifted in time to account for delayed vaccination by month from March to August. A sensitivity analysis was done on possible vaccine coverage changes and considering time gap between vaccine uptake and recommendation. Delaying vaccination from March to end of May prevents more cases over a season, but the variation in cases prevented by month of vaccination is not large. If delaying vaccination results in missed or forgotten vaccination and decrease coverage, delaying vaccination could have a net negative impact. Furthermore, considering a time gap between recommendation and uptake, earlier recommendation is more effective in preventing cases. The results are sensitive to assumptions of intra-seasonal waning of effectiveness. More research is required on intra-seasonal vaccine effectiveness waning and the effect of delayed vaccination on overall uptake to inform any potential changes to current vaccine scheduling recommendations.

Prevalence and predictors of influenza vaccination among residents of long-term care facilities.

Influenza is a respiratory illness which results in significant morbidity and mortality, especially in the older population. Older people living in Long-Term Care Facilities (LTCFs) have a significantly higher risk of infection and complications from influenza. Influenza vaccine is considered the best strategy to prevent infection in high-risk populations. In Australia, the Communicable Diseases Network Australia (CNDA) suggests a vaccination coverage rate of 95% in both staff and residents1. This study aims to measure the vaccination coverage rates for residents in LTCFs and identify predictors of vaccination uptake for these individuals. This study was conducted in nine LTCFs in four sites from March to September 2018. This was done via medical record reviews for residents over 65 years old in these LTCFs, collecting information such as vaccination status, age, gender, ethnicity and occupation. Simple and multivariable logistic regression was used to calculate the Odds Ratio (OR) to determine significant predictors of influenza vaccination uptake. The overall vaccination rate among LTCF residents was 83.6%. Significant predictors of vaccination were LTCF location, ethnicity and previous year vaccination status. Residents in LTCF Site D were less likely to be vaccinated compared to Site A (OR 0.11, 95% CI 0.02-0.61), non-Caucasians were less likely to get vaccinated (OR 0.09, 95% CI 0.01-0.67), and residents who refused the 2017 vaccine were less likely to be vaccinated (OR 0.04, 95% CI 0.01-0.15). Compared with previous Australian studies on LTCF vaccination rates, the overall vaccination rate was high in these LTCFs (83.6% versus 66-84%), but it varied across different sites. Reasons for varying vaccination rates should be explored further - for example, lower rates in non-Caucasians with diverse cultural backgrounds. Better understanding the causes of under-vaccination can help improve vaccination programs in LTCFs.