Impact and management of influenza in aged care facilities in Australia from 2018-2020, including lessons learnt from the COVID-19 pandemic

Aged care facilities in Australia are at high risk of influenza outbreaks with significant mortality and morbidity. Susceptible residents living in close proximity in poorly ventilated and designed facilities, and low vaccination rates among aged care staff have been associated with transmission of influenza. This thesis investigates the impact of influenza and associated policy changes in 9 aged care facilities in Sydney, Australia from 2018 to 2020 highlighting areas of priority that should be addressed by efforts to prevent and control influenza outbreaks. Findings are informed by an analysis of national policies, meta-analysis of published studies and an observational epidemiological study. Most of the evidence for existing infection prevention and control recommendations is based on research conducted in other healthcare settings. There is a substantial gap in the coverage of recommendations on the physical layout of aged care facilities (built environment) in infection control and prevention policies. Existing recommendations lack adequate details, and do not cite high-quality evidence. The meta-analysis found that attack rates were significantly lower in multiple smaller detached facilities than in standalone buildings. A single unit increase in the number of beds and number of common areas was significantly associated with an increase in influenza case counts in our observational study sample. There is some evidence to support the smaller-size cottage model of facilities with adequate space for physical distancing. From 2018 to 2020, influenza case numbers were low in Australia probably due to seasonal variations, introduction of enhanced vaccines among older adults (aged ≥ 65 years old), high vaccination rates among aged care staff and residents and implementation of COVID-19 mitigation measures, and it is challenging to isolate the impact of each factor. Aged care staff who were less than 40 years old, current smokers and overseas-born were identified as less likely to be repeatedly vaccinated against influenza. To tailor vaccination campaigns, further qualitative study on barriers to vaccination would be useful. Understanding gained in the thesis can help formulate policies at the facility level and guide future research on prevention and control measures in response to influenza outbreaks in aged care facilities especially to improve surveillance, vaccination and physical layout

Association of influenza infection and vaccination with cardiac biomarkers and left ventricular ejection fraction in patients with acute myocardial infarction

Aims: The aim of this study was to examine the association of influenza infection and vaccination with extent of cardiac damage during acute myocardial infarctions (AMIs) as measured by serum biomarkers and left ventricular ejection function (LVEF) in patients. Methods: Post-hoc analysis was performed on data from a prospective case-control study of influenza and AMI, conducted in a tertiary care hospital in Sydney, Australia. We included 275 cases of AMI, aged ≥ 40 years admitted to the cardiology during the study period. Results: Mean and median CK-MB levels were significantly higher among unvaccinated group compared to vaccinated group (p value < 0.05). Troponin levels were also higher among unvaccinated group compared to vaccinated group; although not statistically significant. Troponin and CKMB values were not statistically different among influenza positive cases and influenza negative cases. Large size infarcts were less frequent among vaccinated cases compared to unvaccinated cases (25% vs 35.5%) and were more frequent among influenza positive cases compared to influenza negative cases (35.3% vs 31.5%), however differences were not statistically significant. LVEF was lower among vaccinated cases compared to unvaccinated cases (62.5% vs. 52.8%) and influenza positive cases compared to influenza negative cases (58.8% vs 55.4), however differences were not significant. Conclusion: Lower CKMB levels among vaccinated groups showed that influenza vaccine may have a protective effect against large infarcts, therefore influenza vaccination should be recommended for high risk groups. The study suggests an association of larger infarcts with influenza infection, but larger studies are required to confirm this

Modelling of optimal vaccination strategies in response to a bioterrorism associated smallpox outbreak

The reemergence of smallpox as a bioterrorism attack is now an increasing and legitimate concern. Advances in synthetic biology have now made it possible for the virus to be synthesized in a laboratory, with methods publicly available. Smallpox introduction into a susceptible population, with increased immunosuppression and an aging population, raises questions of how vaccination should be used in an epidemic situation when supply may be limited. We constructed three modified susceptible-latent-infectious-recovered (SEIR) models to simulate targeted, ring and mass vaccination in response to a smallpox outbreak in Sydney, Australia. We used age-specific distributions of susceptibility, infectivity, contact rates, and tested outputs under different assumptions. The number of doses needed of second- and third-generation vaccines are estimated, along with the total number of deaths at the end of the epidemic. We found a faster response is the key and ring vaccination of traced contacts is the most effective strategy and requires a smaller number of doses. However if public health authorities are unable to trace a high proportion of contacts, mass vaccination with at least 125,000 doses delivered per day is required. This study informs a better preparedness and response planning for vaccination in a case of a smallpox outbreak in a setting such as Sydney

Tomato flu/fever - An analysis of the Hand Foot and Mouth Disease outbreak reported in India.

The term “Tomato Flu” or “Tomato Fever” is the colloquial term in India used to describe multiple diseases that present with a fever and rash, with characteristic red, “tomato” shaped blister that appears on different parts of the body, which begin small and increase in size as disease progresses. Some controversy exists on this ‘new viral “flu” that emerged in May 2022 over a period of 2 weeks in areas in the south of India. Currently, local healthcare workers have been encouraged to address the disease as a variant of Hand Foot and Mouth Disease to avoid unnecessary panic on the emergence of a “new outbreak”. With the circulation of other viruses, inadequate testing and poor-quality surveillance in a low resource setting, where healthcare systems are already burdened with ongoing monkeypox outbreak and COVID-19 pandemic, the use of colloquial terms may cause unnecessary panic in the current hypervigilant climate. Confirmation from Government is required to confirm whether this outbreak is due to a mixed infection or a variant of the highly infectious Hand Foot and Mouth Disease virus

Legionnaires’ disease: A critical report of the pneumonia of unknown origin outbreak in Argentina

An outbreak of pneumonia of unknown origin was identified in a health facility in Tucumán, Argentina in August 2022. Initial laboratory testing has suggested Legionella pneumophila and Legionella spp. as the causative agent of this pneumonia cluster. However, confirmation of these early results is ongoing and requires identification of the bacteria in environmental samples, matching of environmental samples to patient samples and wider testing of those affected by the outbreak. Official identification of a Legionnaires’ disease outbreak faces many challenges including limited diagnostic capabilities in local laboratories, reduced sensitivity of available tests and inadequate clinical samples. In the absence of official identification of the source of the outbreak, other differential diagnoses for pneumonia should not be overlooked as this may result in missed cases and inadequate control measures being implemented

Systematic review of influenza vaccine effectiveness against laboratory-confirmed influenza among older adults living in aged care facilities

ABSTRACTWe estimated the effectiveness of influenza vaccines in preventing laboratory-confirmed influenza among older adults in aged care. Electronic database searches were conducted using search terms, and studies were selected as per the selection criteria. Fourteen studies were included for final review. The studies exhibited considerable variation in reported vaccine effectiveness (VE) across different seasons. Among the observational studies, VE ranged from 7.2% to 89.8% against laboratory-confirmed influenza across different vaccines. Randomized clinical trials demonstrated a 17% reduction in infection rates with the adjuvanted trivalent vaccine. The limitations include the small number of included studies conducted in different countries or regions, varied seasons, variations in diagnostic testing methods, a focus on the A/H3N2 strain, and few studies available on the effectiveness of enhanced influenza vaccines in aged care settings. Despite challenges associated with achieving optimal protection, the studies showed the benefits of influenza vaccination in the elderly 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

SARS-CoV-2 Delta variant: a systematic review of transmissibility and severity in children

Objectives: To review the evidence of the transmissibility and severity of infection with the Delta variant of SARS-CoV-2 in children. Design: Systematic review. Data sources: PubMed, Embase, medRxiv, Web of Science, and WHO COVID database. Study selection: English language original articles, case reports, commentaries, and letters with relevant primary data, which examined evidence for the transmissibility and severity of infection with the Delta variant of SARS-CoV-2 in children. Methods: Five databases were searched for articles from the period October 2020 to March 2022. Reference lists of eligible studies and grey literature were hand searched for additional studies for inclusion. Articles that provided adequate epidemiological data including infection, transmission, or severity (including hospitalisation and death) with probable or confirmed cases of the Delta variant of SARS-CoV-2 in children (aged ≤9 years) and adolescents (aged 10 to 19 years) were included. Data were extracted for country of origin; participant characteristics (age and sex); sample size; vaccination status; and outcomes, including incidence, secondary attack rate, hospitalisation, ICU, and mortality. All included studies were assessed for bias using the Joanna Briggs Institute Critical Appraisal checklists. Results: 298 studies were found through database searching. After screening, 21 studies were included in the systematic review. Of the included studies, all were deemed to be of moderate to high quality, therefore all were included in the final analysis. Increased incidence was reported in two population studies in the USA and Australia during the period of Delta predominance. Age-related data were available for 14 studies and showed higher rates of infection in older children compared to younger children. Attack rates in educational settings were higher when an adult was the primary case. Data on severity were available from 12 studies and showed that severe disease remained rare, with increasing hospitalisation numbers in proportion to increasing paediatric cases. Vaccination was protective for severe disease, with studies in the United States, Israel and Europe showing less healthcare encounters, emergency department presentations and hospitalisations amongst vaccinated adolescents. Several studies pointed to educational and household settings as key sites for paediatric infection with the Delta variant. Conclusion: A growing proportion of COVID-19 cases were diagnosed in children during the study period due to increased transmissibility of the SARS-CoV-2 Delta variant, with an increasing number of outbreaks observed in household and educational settings likely attributed to low vaccine coverage among children. While severe disease remains uncommon, the impact of vaccination in both adults and adolescents has been shown to reduce paediatric hospitalisation rates

Influence of Population Immunosuppression and Past Vaccination on Smallpox Reemergence

We built a SEIR (susceptible, exposed, infected, recovered) model of smallpox transmission for New York, New York, USA, and Sydney, New South Wales, Australia, that accounted for age-specific population immunosuppression and residual vaccine immunity and conducted sensitivity analyses to estimate the effect these parameters might have on smallpox reemergence. At least 19% of New York’s and 17% of Sydney’s population are immunosuppressed. The highest smallpox infection rates were in persons 0–19 years of age, but the highest death rates were in those >45 years of age. Because of the low level of residual vaccine immunity, immunosuppression was more influential than vaccination on death and infection rates in our model. Despite widespread smallpox vaccination until 1980 in New York, smallpox outbreak severity appeared worse in New York than in Sydney. Immunosuppression is highly prevalent and should be considered in future smallpox outbreak models because excluding this factor probably underestimates death and infection rates