TY - JOUR

T1 - Modelling the impact of relaxing COVID-19 control measures during a period of low viral transmission

AU - Scott, Nick

AU - Palmer, Anna

AU - Delport, Dominic

AU - Abeysuriya, Romesh

AU - Stuart, Robyn M

AU - Kerr, Cliff C

AU - Mistry, Dina

AU - Klein, Daniel J

AU - Sacks‐davis, Rachel

AU - Heath, Katie

AU - Hainsworth, Samuel W

AU - Pedrana, Alisa

AU - Stoove, Mark

AU - Wilson, David

AU - Hellard, Margaret E

PY - 2021

Y1 - 2021

N2 - ObjectivesTo assess the risks associated with relaxing coronavirus disease 2019 (COVID-19)-related physical distancing restrictions and lockdown policies during a period of low viral transmission.DesignNetwork-based viral transmission risks in households, schools, workplaces, and a variety of community spaces and activities were simulated in an agent-based model, Covasim.SettingThe model was calibrated for a baseline scenario reflecting the epidemiological and policy environment in Victoria during March–May 2020, a period of low community viral transmission.InterventionPolicy changes for easing COVID-19-related restrictions from May 2020 were simulated in the context of interventions that included testing, contact tracing (including with a smartphone app), and quarantine.Main outcome measureIncrease in detected COVID-19 cases following relaxation of restrictions.ResultsPolicy changes that facilitate contact of individuals with large numbers of unknown people (eg, opening bars, increased public transport use) were associated with the greatest risk of COVID-19 case numbers increasing; changes leading to smaller, structured gatherings with known contacts (eg, small social gatherings, opening schools) were associated with lower risks. In our model, the rise in case numbers following some policy changes was notable only two months after their implementation.ConclusionsRemoving several COVID-19-related restrictions within a short period of time should be undertaken with care, as the consequences may not be apparent for more than two months. Our findings support continuation of work from home policies (to reduce public transport use) and strategies that mitigate the risk associated with re-opening of social venues.

AB - ObjectivesTo assess the risks associated with relaxing coronavirus disease 2019 (COVID-19)-related physical distancing restrictions and lockdown policies during a period of low viral transmission.DesignNetwork-based viral transmission risks in households, schools, workplaces, and a variety of community spaces and activities were simulated in an agent-based model, Covasim.SettingThe model was calibrated for a baseline scenario reflecting the epidemiological and policy environment in Victoria during March–May 2020, a period of low community viral transmission.InterventionPolicy changes for easing COVID-19-related restrictions from May 2020 were simulated in the context of interventions that included testing, contact tracing (including with a smartphone app), and quarantine.Main outcome measureIncrease in detected COVID-19 cases following relaxation of restrictions.ResultsPolicy changes that facilitate contact of individuals with large numbers of unknown people (eg, opening bars, increased public transport use) were associated with the greatest risk of COVID-19 case numbers increasing; changes leading to smaller, structured gatherings with known contacts (eg, small social gatherings, opening schools) were associated with lower risks. In our model, the rise in case numbers following some policy changes was notable only two months after their implementation.ConclusionsRemoving several COVID-19-related restrictions within a short period of time should be undertaken with care, as the consequences may not be apparent for more than two months. Our findings support continuation of work from home policies (to reduce public transport use) and strategies that mitigate the risk associated with re-opening of social venues.

U2 - 10.5694/mja2.50845

DO - 10.5694/mja2.50845

M3 - Journal article

C2 - 33207390

VL - 214

SP - 79

EP - 83

JO - Medical Journal of Australia

JF - Medical Journal of Australia

SN - 0025-729X

IS - 2

ER -