COVID-19 vaccine coverage targets to inform reopening plans in a low incidence setting

Since the emergence of SARS-CoV-2 in 2019 through to mid-2021, much of the Australian population lived in a COVID-19 free environment. This followed the broadly successful implementation of a strong suppression strategy, including international border closures. With the availability of COVID-19 vaccines in early 2021, the national government sought to transition from a state of minimal incidence and strong suppression activities to one of high vaccine coverage and reduced restrictions but with still-manageable transmission. This transition is articulated in the national "re-opening" plan released in July 2021. Here we report on the dynamic modelling study that directly informed policies within the national re-opening plan including the identification of priority age groups for vaccination, target vaccine coverage thresholds and the anticipated requirements for continued public health measures -- assuming circulation of the Delta SARS-CoV-2 variant. Our findings demonstrated that adult vaccine coverage needed to be at least 70% to minimise public health and clinical impacts following the establishment of community transmission. They also supported the need for continued application of test-trace-isolate-quarantine and social measures during the vaccine roll-out phase and beyond.

Is vaginal laxity an early symptom of pelvic organ prolapse?

INTRODUCTION AND HYPOTHESIS: We aimed to determine whether vaginal laxity (VL) may be an early symptom of pelvic organ prolapse (POP). METHODS: This was a retrospective observational study including patients referred to a urogynecological clinic owing to symptoms of pelvic floor dysfunction. The interview included inquiry about VL and POP symptoms. Clinical examination and translabial ultrasound (TLUS) were performed to assess for POP and levator hiatal ballooning. Analysis of ultrasound datasets was performed with the reviewer blinded against all other data. Linear regression models were used to evaluate associations between age categories and symptoms. RESULTS: The analysis included 531 patients. Mean age was 59.7 years (range 17.6-92.0), mean body mass index (BMI) was 29.5 kg/m2 (14.7-53.5) and 458 (86%) were vaginally parous. Overall, POP symptoms were reported by 258 patients (49%) and VL by 118 (22%). Significant clinical POP was diagnosed in 384 patients (72%). Levator hiatal ballooning on TLUS was noticed in 56%. VL and POP symptoms showed a divergent association with age (p = 0.02). This trend remained significant after controlling for clinically significant POP (p = 0.01) and levator hiatal ballooning (p = 0.002). Of 384 women with significant objective POP, 231 (60%) reported symptoms of POP. Of 153 women with asymptomatic POP, 7 (5%) reported symptoms of VL. CONCLUSIONS: With increasing age the prevalence of VL decreases, whereas symptoms of POP increase. However, only very few women with objective POP perceive VL as their only symptom, independent of age at presentation. Therefore, vaginal laxity does not seem to be an early symptom of prolapse.

INFERRED RESOLUTION THROUGH HERD IMMMUNITY OF FIRST COVID-19 WAVE IN MANAUS, BRAZILIAN AMAZON

INTRODUCTORY PARAGRAPHAs in many other settings, peak excess mortality preceded the officially reported first wave peak of the COVID-19 epidemic in Manaus, Brazil, reflecting delayed case recognition and limited initial access to diagnostic testing. To avoid early information bias, we used detailed age and gender stratified death certificate and hospitalisation data to evaluate the epidemics trajectory and infer the cause of its decline using a stochastic model. Our results are consistent with heterogenous transmission reducing over time due to the development of herd immunity. Relative to a baseline model that assumed homogenous mixing across Manaus, a model that permitted a small, self-isolated population fraction raised the estimated herd-immunity threshold from 28% to 30% and reduced the final attack rate from 86% to 65%. In the latter scenario, a substantial proportion of vulnerable, older individuals remained susceptible to infection. Given uncertainties regarding the distancing behaviours of population subgroups with different social and economic characteristics, and the duration of sterilising or transmission-modifying immunity in exposed individuals, we conclude that the potential for epidemic outbreaks remains, but that future waves of infection are likely to be much less pronounced than that already experienced.

Ultrasonic degradation of perfluorooctane sulfonic acid (PFOS) correlated with sonochemical and sonoluminescence characterisation.

Sonolysis has been proposed as a promising treatment technology to remove per- and polyfluoroalkyl substances (PFASs) from contaminated water. The mechanism of degradation is generally accepted to be high temperature pyrolysis at the bubble surface with dependency upon surface reaction site availability. However, the parametric effects of the ultrasonic system on PFAS degradation are poorly understood, making upscale challenging and leading to less than optimal use of ultrasonic energy. Hence, a thorough understanding of these parametric effects could lead to improved efficiency and commercial viability. Here, reactor characterisation was performed at 44, 400, 500, and 1000 kHz using potassium iodide (KI) dosimetry, sonochemiluminescence (SCL), and sonoluminescence (SL) in water and a solution of potassium salt of PFOS (hereafter, K-PFOS). Then the degradation of K-PFOS (10 mg L-1 in 200 mL solution) was investigated at these four frequencies. At 44 kHz, no PFOS degradation was observed. At 400, 500, and 1000 kHz the amount of degradation was 96.9, 93.8, and 91.2%, respectively, over four hours and was accompanied by stoichiometric fluoride release, indicating mineralisation of the PFOS molecule. Close correlation of PFOS degradation trends with KI dosimetry and SCL intensity was observed, which suggested degradation occurred under similar conditions to these sonochemical processes. At 1000 kHz, where the overall intensity of collapse was significantly reduced (measured by SL), PFOS degradation was not similarly decreased. Discussion is presented that suggests a hydrated electron degradation mechanism for PFOS may occur in ultrasonic conditions. This mechanism is a novel hypothesis in the field of PFAS sonolysis.

Early analysis of the Australian COVID-19 epidemic

As of 18 April 2020, there had been 6,533 confirmed cases of COVID-19 in Australia [1]. Of these, 67 had died from the disease. The daily count of new confirmed cases was declining. This suggests that the collective actions of the Australian public and government authorities in response to COVID-19 were sufficiently early and assiduous to avert a public health crisis -- for now. Analysing factors, such as the intensity and timing public health interventions, that contribute to individual country experiences of COVID-19 will assist in the next stage of response planning globally. Using data from the Australian national COVID-19 database, we describe how the epidemic and public health response unfolded in Australia up to 13 April 2020. We estimate that the effective reproduction number was likely below 1 (the threshold value for control) in each Australian state since mid-March and forecast that hospital ward and intensive care unit occupancy will remain below capacity thresholds over the next two weeks.

Modelling the impact of COVID-19 in Australia to inform transmission reducing measures and health system preparedness

BackgroundThe ability of global health systems to cope with increasing numbers of COVID-19 cases is of major concern. In readiness for this challenge, Australia has drawn on clinical pathway models developed over many years in preparation for influenza pandemics. These models have been used to estimate health care requirements for COVID-19 patients, in the context of broader public health measures. MethodsAn age and risk stratified transmission model of COVID-19 infection was used to simulate an unmitigated epidemic with parameter ranges reflecting uncertainty in current estimates of transmissibility and severity. Overlaid public health measures included case isolation and quarantine of contacts, and broadly applied social distancing. Clinical presentations and patient flows through the Australian health care system were simulated, including expansion of available intensive care capacity and alternative clinical assessment pathways. FindingsAn unmitigated COVID-19 epidemic would dramatically exceed the capacity of the Australian health system, over a prolonged period. Case isolation and contact quarantine alone will be insufficient to constrain case presentations within a feasible level of expansion of health sector capacity. Overlaid social restrictions will need to be applied at some level over the course of the epidemic to ensure that systems do not become overwhelmed, and that essential health sector functions, including care of COVID-19 patients, can be maintained. Attention to the full pathway of clinical care is needed to ensure access to critical care. InterpretationReducing COVID-19 morbidity and mortality will rely on a combination of measures to strengthen and extend public health and clinical capacity, along with reduction of overall infection transmission in the community. Ongoing attention to maintaining and strengthening the capacity of health care systems and workers to manage cases is needed. FundingAustralian Government Department of Health Office of Health Protection, Australian Government National Health and Medical Research Council