In the early stage of an infectious disease outbreak,public health strategies tend to gravitate towards non-pharmaceutical interventions(NPIs)given the time required to develop targeted treatments and vaccines.One of ...In the early stage of an infectious disease outbreak,public health strategies tend to gravitate towards non-pharmaceutical interventions(NPIs)given the time required to develop targeted treatments and vaccines.One of the most common NPIs is Test-Trace-Isolate(TTI).One of the factors determining the effectiveness of TTI is the ability to identify contacts of infected individuals.In this study,we propose a multi-layer temporal contact network to model transmission dynamics and assess the impact of different TTI implementations,using SARS-CoV-2 as a case study.The model was used to evaluate TTI effectiveness both in containing an outbreak and mitigating the impact of an epidemic.We estimated that a TTI strategy based on home isolation and testing of both primary and secondary contacts can contain outbreaks only when the reproduction number is up to 1.3,at which the epidemic prevention potential is 88.2%(95%CI:87.9%e88.5%).On the other hand,for higher value of the reproduction number,TTI is estimated to noticeably mitigate disease burden but at high social costs(e.g.,over a month in isolation/quarantine per person for reproduction numbers of 1.7 or higher).We estimated that strategies considering quarantine of contacts have a larger epidemic prevention potential than strategies that either avoid tracing contacts or require contacts to be tested before isolation.Combining TTI with other social distancing measures can improve the likelihood of successfully containing an outbreak but the estimated epidemic prevention potential remains lower than 50%for reproduction numbers higher than 2.1.In conclusion,our model-based evaluation highlights the challenges of relying on TTIs to contain an outbreak of a novel pathogen with characteristics similar to SARS-CoV-2,and that the estimated effectiveness of TTI depends on the way contact patterns are modeled,supporting the relevance of obtaining comprehensive data on human social interactions to improve preparedness.展开更多
Background:Countries that aimed for eliminating the cases of COVID-19 with test-trace-isolate policy are found to have lower infections,deaths,and better economic performance,compared with those that opted for other m...Background:Countries that aimed for eliminating the cases of COVID-19 with test-trace-isolate policy are found to have lower infections,deaths,and better economic performance,compared with those that opted for other mitigation strategies.However,the continuous evolution of new strains has raised the question of whether COVID-19 eradication is still possible given the limited public health response capacity and fatigue of the epidemic.We aim to investigate the mechanism of the Zero-COVID policy on outbreak containment,and to explore the possibility of eradication of Omicron transmission using the citywide test-trace-isolate(CTTI)strategy.Methods:We develop a compartmental model incorporating the CTTI Zero-COVID policy to understand how it contributes to the SARS-CoV-2 elimination.We employ our model to mimic the Delta outbreak in Fujian Province,China,from September 10 to October 9,2021,and the Omicron outbreak in Jilin Province,China for the period from March 1 to April 1,2022.Projections and sensitivity analyses were conducted using dynamical system and Latin Hypercube Sampling/Partial Rank Correlation Coefcient(PRCC).Results:Calibration results of the model estimate the Fujian Delta outbreak can end in 30(95%confdence interval CI:28–33)days,after 10(95%CI:9–11)rounds of citywide testing.The emerging Jilin Omicron outbreak may achieve zero COVID cases in 50(95%CI:41–57)days if supported with sufcient public health resources and population compliance,which shows the efectiveness of the CTTI Zero-COVID policy.Conclusions:The CTTI policy shows the capacity for the eradication of the Delta outbreaks and also the Omicron outbreaks.Nonetheless,the implementation of radical CTTI is challenging,which requires routine monitoring for early detection,adequate testing capacity,efcient contact tracing,and high isolation compliance,which constrain its benefts in regions with limited resources.Moreover,these challenges become even more acute in the face of more contagious variants with a high proportion of asymptomatic cases.Hence,in regions where CTTI is not possible,personal protection,public health control measures,and vaccination are indispensable for mitigating and exiting the COVID-19 pandemic.展开更多
基金supported by the National Natural Science Foundation of China(No.62373264)the Major Program of National Fund of Philosophy and Social Science of China(No.20&ZD112)the 111 Project under grant agreement B21044.
文摘In the early stage of an infectious disease outbreak,public health strategies tend to gravitate towards non-pharmaceutical interventions(NPIs)given the time required to develop targeted treatments and vaccines.One of the most common NPIs is Test-Trace-Isolate(TTI).One of the factors determining the effectiveness of TTI is the ability to identify contacts of infected individuals.In this study,we propose a multi-layer temporal contact network to model transmission dynamics and assess the impact of different TTI implementations,using SARS-CoV-2 as a case study.The model was used to evaluate TTI effectiveness both in containing an outbreak and mitigating the impact of an epidemic.We estimated that a TTI strategy based on home isolation and testing of both primary and secondary contacts can contain outbreaks only when the reproduction number is up to 1.3,at which the epidemic prevention potential is 88.2%(95%CI:87.9%e88.5%).On the other hand,for higher value of the reproduction number,TTI is estimated to noticeably mitigate disease burden but at high social costs(e.g.,over a month in isolation/quarantine per person for reproduction numbers of 1.7 or higher).We estimated that strategies considering quarantine of contacts have a larger epidemic prevention potential than strategies that either avoid tracing contacts or require contacts to be tested before isolation.Combining TTI with other social distancing measures can improve the likelihood of successfully containing an outbreak but the estimated epidemic prevention potential remains lower than 50%for reproduction numbers higher than 2.1.In conclusion,our model-based evaluation highlights the challenges of relying on TTIs to contain an outbreak of a novel pathogen with characteristics similar to SARS-CoV-2,and that the estimated effectiveness of TTI depends on the way contact patterns are modeled,supporting the relevance of obtaining comprehensive data on human social interactions to improve preparedness.
文摘Background:Countries that aimed for eliminating the cases of COVID-19 with test-trace-isolate policy are found to have lower infections,deaths,and better economic performance,compared with those that opted for other mitigation strategies.However,the continuous evolution of new strains has raised the question of whether COVID-19 eradication is still possible given the limited public health response capacity and fatigue of the epidemic.We aim to investigate the mechanism of the Zero-COVID policy on outbreak containment,and to explore the possibility of eradication of Omicron transmission using the citywide test-trace-isolate(CTTI)strategy.Methods:We develop a compartmental model incorporating the CTTI Zero-COVID policy to understand how it contributes to the SARS-CoV-2 elimination.We employ our model to mimic the Delta outbreak in Fujian Province,China,from September 10 to October 9,2021,and the Omicron outbreak in Jilin Province,China for the period from March 1 to April 1,2022.Projections and sensitivity analyses were conducted using dynamical system and Latin Hypercube Sampling/Partial Rank Correlation Coefcient(PRCC).Results:Calibration results of the model estimate the Fujian Delta outbreak can end in 30(95%confdence interval CI:28–33)days,after 10(95%CI:9–11)rounds of citywide testing.The emerging Jilin Omicron outbreak may achieve zero COVID cases in 50(95%CI:41–57)days if supported with sufcient public health resources and population compliance,which shows the efectiveness of the CTTI Zero-COVID policy.Conclusions:The CTTI policy shows the capacity for the eradication of the Delta outbreaks and also the Omicron outbreaks.Nonetheless,the implementation of radical CTTI is challenging,which requires routine monitoring for early detection,adequate testing capacity,efcient contact tracing,and high isolation compliance,which constrain its benefts in regions with limited resources.Moreover,these challenges become even more acute in the face of more contagious variants with a high proportion of asymptomatic cases.Hence,in regions where CTTI is not possible,personal protection,public health control measures,and vaccination are indispensable for mitigating and exiting the COVID-19 pandemic.
