Thailand population

Population-based analysis of epidemiological characteristics of COVID-19 outbreaks in Victoria, Australia, January 2020 – March 2021, and their suppression through comprehensive control strategies


Discussion

Due to the comprehensive control measures implemented, the epidemic in Victoria was low compared to many regions internationally. The overall attack rate of 3,023 per million at the end of 2020 was far lower than that of the United States (56,341 / million), the United Kingdom (33,232 / million) and Canada (14,289 per million ), but much more than some regional neighbors, including Thailand. (86 / million), Vietnam (15 / million) and Fiji (51 / million) [
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]. There were 111 deaths per million, reflecting the high burden of residential care for the elderly, despite the relatively low incidence, as has been documented internationally [

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].

Our assessment of the epidemic phases experienced in Victoria has several strengths, primarily the almost complete capture of diagnosed cases and test results, resulting from the coordinated and centralized public health response that has occurred within an imposed legislative framework. In addition, data collection and data linkage with state-level hospitalization and death notifications have been improved to facilitate morbidity recording. [
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]and the impacts on mortality. However, data limitations included quality, usability, changing definitions, and changing data collection practices. For example, the proportion of symptomatic cases at the time of testing should be interpreted in light of changes in testing criteria and the completeness of data collection at the height of phase 3, when interviews with cases have been completed. been shortened and symptom data has not been systematically collected, especially in some large epidemic settings, such as elderly care and health care.

The epidemiological features of the Victoria COVID-19 outbreaks described here highlight the challenges of effective prevention and control of SARS-CoV-2, none of which is unique to our environment. There were notable differences in the main epidemiological characteristics of the Victoria epidemic phases. There was a shift towards younger age groups: the highest cumulative incidence rates (adjusted for population size) of phase I were in the 20-29 age groups years and 50-74 year olds, while the highest cumulative incidence rates in phase III were those aged 80. + (associated with the care of the elderly) and 18-29 years (associated with the essential workforce). Phase I (and later IV) was also characterized by foreign acquired infection among cases of high socioeconomic position, while phase III was characterized by locally acquired infections among younger and socially disadvantaged communities. . During this phase, proportionally more cases came from non-English speaking backgrounds.

Consistent with the increase in cases among culturally and linguistically diverse communities, phase III has also been characterized by a large number of transmission events occurring in critical workplaces such as manufacturing, meat processing and care for the elderly. The increase in cases occurring in older Victorians and those residing in elderly care has thus changed the clinical characteristics of phase III to that of an epidemic with a burden of disease and mortality considerably higher than the phases previous epidemics. These complexities have necessitated several improvements in public health prevention and control activities, including: better community engagement and testing among culturally and linguistically diverse communities, income support for those who must self-isolate, housing at the hotel for essential workers unable to isolate themselves safely at home, improved testing and discharge of health workers and – for residents of elderly care facilities – a lower threshold for hospitalization to both minimize the risk of home transmission and manage the clinical deterioration of individual cases.

The transition of older and richer cases to younger and socially disadvantaged communities that was seen in Victoria was also a feature of the early outbreaks in Singapore, where infections among migrant workers living in dormitories dominated their epidemic early on. from 2020 [
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,

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]. The high incidence and burden of disease in disadvantaged communities has also been a hallmark of COVID-19 outbreaks in the United States [

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]and United Kingdom [

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Disparities in the risk and outcomes of COVID-19.

]. People from culturally and linguistically diverse communities are over-represented as workers in essential settings, such as elderly care and slaughterhouses, underscoring the need to ensure that pandemic control measures are adopted. without further aggravating the disadvantage [

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]. Meaningful engagement with communities at high risk of exposure is essential to ensure future public health actions [

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]. To this end, Victoria designed and implemented public health interventions that sought to authentically engage with diverse communities in order to maximize trust and cooperation and mitigate negative impacts. [].

The SARS-CoV-2 escape from Victoria’s hotel quarantine program at the start of Phase III also highlighted the challenges of this pandemic strategy, which used unbuilt facilities for this purpose. The substantial subsequent transmission of the hotel quarantine amplified the need for programmatic reform. Investigations into the hotel quarantine program have since led to key risk mitigation measures including: improved governance and the creation of a single agency to manage this program (COVID-19 Quarantine Victoria), employment a complete hierarchy of infection prevention and control measures, including engineering controls to reduce the potential for aerosol transmission and priority vaccination of hotel quarantine workers []. Travelers returning to hotel quarantine continued to be the main source of new SARS-CoV-2 outbreaks in Australia for the first half of 2021.

Authors

Sheena G. Sullivan, COVID-19 Public Health Division, Department of Health, Victoria and WHO Collaborating Center for Influenza Reference and Research, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia

Julia ML Brotherton, COVID-19 Public Health Division, Department of Health, Victoria and VCS Foundation, Victoria, Australia

Brigid M Lynch, COVID-19 Public Health Division, Department of Health, Victoria and Cancer Council Victoria, Australia

Allison Cheung, COVID-19 Public Health Division, Department of Health and Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia

Michael Lydeamore, Department of Infectious Diseases, The Alfred and Central Clinical School, Monash University, Victoria, Australia

Mark Stevenson, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia

Simon Firestone, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia

Jose Canevari, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Huu Nghia Joey Nguyen, Department of Education and Training, Victoria, Australia

Kylie S. Carville, COVID-19 Public Health Division, Victoria Department of Health and Infectious Disease Reference Laboratory, Victoria, Australia

Hazel J. Clothier, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Jessie Goldsmith, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Naveen Tenneti, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Carrie Barnes, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Nectaria Tzimourtas, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Rebecca F. Gang, COVID-19 Public Health Division, Department of Health, Victoria, Australia

James Armstrong, Health Protection Branch, Department of Health, Victoria, Australia

Lucinda Franklin, Health Protection Branch, Department of Health, Victoria, Australia

Daneeta Hennessy, Health Protection Branch, Department of Health, Victoria, Australia

Kara Martin, Health Protection Branch, Department of Health, Victoria, Australia

Mohana Baptista, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Michael Muleme, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Aaron Osborne, North East Public Health Unit, Victoria, Australia

Charles Alpren, Western Public Health Unit, Victoria, Australia

Frances H. Ampt, Western Public Health Unit, Victoria, Australia

Natasha Castree, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Andres Hernandez, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Annaliese van Diemen, North East Public Health Unit, Victoria, Australia

Allen C. Cheng, COVID-19 Public Health Division, Department of Health, Victoria and Alfred Health, Victoria, Australia

Simon Crouch, South East Public Health Unit, Victoria, Australia

Kira Leeb, COVID-19 Public Health Division, Department of Health, Australia

Kate Matson, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Finn Romanes, Western Public Health Unit, Victoria, Australia

Clare Looker, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Evelyn Wong, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Euan Wallace, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Brett Sutton, COVID-19 Public Health Division, Department of Health, Victoria, Australia

Stacey L Rowe, COVID-19 Public Health Division, Department of Health, Victoria, Australia