Background:The current outbreak of novel coronavirus disease 2019 has caused a seriousdisease burden worldwide.Vaccines are an important factor to sustain the epidemic.Although with a relatively high-vaccination world...Background:The current outbreak of novel coronavirus disease 2019 has caused a seriousdisease burden worldwide.Vaccines are an important factor to sustain the epidemic.Although with a relatively high-vaccination worldwide,the decay of vaccine efficacy andthe arising of new variants lead us to the challenge of maintaining a sufficient immunebarrier to protect the population.Method:A case-contact tracking data in Hunan,China,is used to estimate the contactpattern of cases for scenarios including school,workspace,etc,rather than ordinary susceptible population.Based on the estimated vaccine coverage and efficacy,a multi-groupvaccinated-exposed-presymptomatic-symptomatic-asymptomatic-removed model(VEFIAR)with 8 age groups,with each partitioned into 4 vaccination status groups isdeveloped.The optimal dose-wise vaccinating strategy is optimized based on the currentlyestimated immunity barrier of coverage and efficacy,using the greedy algorithm thatminimizes the cumulative cases,population size of hospitalization and fatality respectivelyin a certain future interval.Parameters of Delta and Omicron variants are used respectivelyin the optimization.Results:The estimated contact matrices of cases showed a concentration on middle ages,and has compatible magnitudes compared to estimations from contact surveys in otherstudies.The VEFIAR model is numerically stable.The optimal controled vaccination strategy requires immediate vaccination on the un-vaccinated high-contact population of age30e39 to reduce the cumulative cases,and is stable with different basic reproductionnumbers(R_(0)).As for minimizing hospitalization and fatality,the optimized strategy requires vaccination on the un-vaccinated of both aged 30e39 of high contact frequencyand the vulnerable older.Conclusion:The objective of reducing transmission requires vaccination in age groups ofthe highest contact frequency,with more priority for un-vaccinated than un-fully or fullyvaccinated.The objective of reducing total hospitalization and fatality requires not only toreduce transmission but also to protect the vulnerable older.The priority changes byvaccination progress.For any region,if the local contact pattern is available,then with thevaccination coverage,efficacy,and disease characteristics of relative risks in heterogeneouspopulations,the optimal dose-wise vaccinating process will be obtained and gives hintsfor decision-making.展开更多
Under the background of high-speed rail networking, this paper uses the passenger trains, the type and direction of the railway via Hang Yong and its extension road line, to construct adsorption and dependency index a...Under the background of high-speed rail networking, this paper uses the passenger trains, the type and direction of the railway via Hang Yong and its extension road line, to construct adsorption and dependency index among cities, depict the contact pattern between the Hang Yong dual-core and its hinterland, measure the “net effect” that two center cities (Hangzhou, Ningbo) have on their hinterland, and estimate population agglomeration potential and future possible population flows of Zhejiang Province and the main sample cities. The result shows that, compared with Ningbo, Hangzhou has stronger radiation force to the vast majority of sample cities, and the sample cities affected more by Ningbo mainly concentrates in Ningbo-Taizhou-Wenzhou along;in addition, the sample cities such as Hangzhou, Ningbo and so on show better population agglomeration, then the population “scramble” phenomenon between cities has begun to appear.展开更多
Background:The pandemic of coronavirus disease 2019(COVID-19)has changed human behavior in areas such as contact patterns and mask-wearing frequency.Exploring human–human contact patterns and mask-wearing habits in h...Background:The pandemic of coronavirus disease 2019(COVID-19)has changed human behavior in areas such as contact patterns and mask-wearing frequency.Exploring human–human contact patterns and mask-wearing habits in high-risk groups is an essential step in fully understanding the transmission of respiratory infection-based diseases.This study had aims to quantify local human–human(H–H)contacts in high-risk groups in representative provinces of China and to explore the occupation-specific assortativity and heterogeneity of social contacts.Methods:Delivery workers,medical workers,preschoolers,and students from Qinghai,Shanghai,and Zhejiang were recruited to complete an online questionnaire that queried general information,logged contacts,and assessed the willingness to wear a mask in different settings.The“group contact”was defined as contact with a group at least 20 individuals.The numbers of contacts across different characteristics were assessed and age-specific contact matrices were established.A generalized additive mixed model was used to analyze the associations between the number of individual contacts and several characteristics.The factors influencing the frequency of mask wearing were evaluated with a logistic regression model.Results:A total of 611,287 contacts were reported by 15,635 participants.The frequency of daily individual contacts averaged 3.14(95%confidence interval:3.13–3.15)people per day,while that of group contacts was 37.90(95%CI:37.20–38.70).Skin-to-skin contact and long-duration contact were more likely to occur at home or among family members.Contact matrices of students were the most assortative(all contacts q-index=0.899,95%CI:0.894–0.904).Participants with larger household sizes reported having more contacts.Higher household income per capita was significantly associated with a greater number of contacts among preschoolers(P_(50,000–99,999)=0.033)and students(P_(10,000–29,999)=0.017).In each of the public places,the frequency of mask wearing was highest for delivery workers.For preschoolers and students with more contacts,the proportion of those who reported always wearing masks was lower(P<0.05)in schools/workplaces and public transportation than preschoolers and students with fewer contacts.Conclusions:Contact screening efforts should be concentrated in the home,school,and workplace after an outbreak of an epidemic,as more than 75%of all contacts,on average,will be found in such places.Efforts should be made to improve the mask-wearing rate and age-specific health promotion measures aimed at reducing transmission for the younger demographic.Age-stratified and occupation-specific social contact research in high-risk groups could help inform policy-making decisions during the post-relaxation period of the COVID-19 pandemic.展开更多
An AI-empowered indoor digital contact-tracing system was developed using a centralized architecture and advanced low-energy Bluetooth technologies for indoor positioning,with careful preservation of privacy and data ...An AI-empowered indoor digital contact-tracing system was developed using a centralized architecture and advanced low-energy Bluetooth technologies for indoor positioning,with careful preservation of privacy and data security.We analyzed the contact pattern data from two RCHs and investigated a COVID-19 outbreak in one study site.To evaluate the effectiveness of the system in containing outbreaks with minimal contacts under quarantine,a simulation study was conducted to compare the impact of different quarantine strategies on outbreak containment within RCHs.The significant difference in contact hours between weekdays and weekends was observed for some pairs of RCH residents and staff during the two-week data collection period.No significant difference between secondary cases and uninfected contacts was observed in a COVID-19 outbreak in terms of their demographics and contact patterns.Simulation results based on the collected contact data indicated that a threshold of accumulative contact hours one or two days prior to diagnosis of the index case could dramatically increase the efficiency of outbreak containment within RCHs by targeted isolation of the close contacts.This study demonstrated the feasibility and efficiency of employing an AI-empowered system in indoor digital contact tracing of outbreaks in RCHs in the post-pandemic era.展开更多
COVID-19 has triggered an unprecedented public health crisis and a global economic shock.As countries and cities have transitioned away from strict pandemic restrictions,the most effective reopening strategies may var...COVID-19 has triggered an unprecedented public health crisis and a global economic shock.As countries and cities have transitioned away from strict pandemic restrictions,the most effective reopening strategies may vary significantly based on their demographic characteristics and social contact patterns.In this study,we employed an extended agespecific compartment model that incorporates population mobility to investigate the interaction between population age structure and various containment interventions in New York,Los Angeles,Daegu,and Nairobi e four cities with distinct age distributions that served as local epicenters of the epidemic from January 2020 to March 2021.Our results demonstrated that individual social distancing or quarantine strategies alone cannot effectively curb the spread of infection over a one-year period.However,a combined strategy,including school closure,50%working from home,50%reduction in other mobility,10%quarantine rate,and city lockdown interventions,can effectively suppress the infection.Furthermore,our findings revealed that social-distancing policies exhibit strong age-specific effects,and age-targeted interventions can yield significant spillover benefits.Specifically,reducing contact rates among the population under 20 can prevent 14%,18%,56%,and 99%of infections across all age groups in New York,Los Angeles,Daegu,and Nairobi,respectively,surpassing the effectiveness of policies exclusively targeting adults over 60 years old.In particular,to protect the elderly,it is essential to reduce contacts between the younger population and people of all age groups,especially those over 60 years old.While an older population structure may escalate fatality risk,it might also decrease infection risk.Moreover,a higher basic reproduction number amplifies the impact of an older population structure on the fatality risk of the elderly.The considerable variations in susceptibility,severity,and mobility across age groups underscore the need for targeted interventions to effectively control the spread of COVID-19 and mitigate risks in future pandemics.展开更多
COVID-19 has been prevalent worldwide for about 2 years now and has brought unprecedented challenges to our society.Before vaccines were available,the main disease intervention strategies were non-pharmaceutical.Start...COVID-19 has been prevalent worldwide for about 2 years now and has brought unprecedented challenges to our society.Before vaccines were available,the main disease intervention strategies were non-pharmaceutical.Starting December 2020,in Ontario,Canada,vaccines were approved for administering to vulnerable individuals and gradually expanded to all individuals above the age of 12.As the vaccine coverage reached a satisfactory level among the eligible population,normal social activities resumed and schools reopened starting September 2021.However,when schools reopen for in-person learning,children under the age of 12 are unvaccinated and are at higher risks of contracting the virus.We propose an age-stratified model based on the age and vaccine eligibility of the individuals.We fit our model to the data in Ontario,Canada and obtain a good fitting result.The results show that a relaxed between-group contact rate may trigger future epidemic waves more easily than an increased within-group contact rate.An increasing mixed contact rate of the older group quickly amplifies the daily incidence numbers for both groups whereas an increasing mixed contact rate of the younger group mainly leads to future waves in the younger group alone.The results indicate the importance of accelerating vaccine rollout for younger individuals in mitigating disease spread.展开更多
基金supported by the National Key Research and Development Program of China(2021YFC2301604)the Research Project on Education and Teaching Reform of Undergraduate Universities of Fujian Province,China(FBJG20210260)+2 种基金the Self-supporting Program of Guangzhou Laboratory(Grant No.SRPG22-007)the Bill&Melinda Gates Foundation(Grant INV-005834 to T.C.)the Research on the Precise Prevention and Control System of SARS-Cov-2(Grant No.35022022YJ07,Topic No.2022YJ-3).
文摘Background:The current outbreak of novel coronavirus disease 2019 has caused a seriousdisease burden worldwide.Vaccines are an important factor to sustain the epidemic.Although with a relatively high-vaccination worldwide,the decay of vaccine efficacy andthe arising of new variants lead us to the challenge of maintaining a sufficient immunebarrier to protect the population.Method:A case-contact tracking data in Hunan,China,is used to estimate the contactpattern of cases for scenarios including school,workspace,etc,rather than ordinary susceptible population.Based on the estimated vaccine coverage and efficacy,a multi-groupvaccinated-exposed-presymptomatic-symptomatic-asymptomatic-removed model(VEFIAR)with 8 age groups,with each partitioned into 4 vaccination status groups isdeveloped.The optimal dose-wise vaccinating strategy is optimized based on the currentlyestimated immunity barrier of coverage and efficacy,using the greedy algorithm thatminimizes the cumulative cases,population size of hospitalization and fatality respectivelyin a certain future interval.Parameters of Delta and Omicron variants are used respectivelyin the optimization.Results:The estimated contact matrices of cases showed a concentration on middle ages,and has compatible magnitudes compared to estimations from contact surveys in otherstudies.The VEFIAR model is numerically stable.The optimal controled vaccination strategy requires immediate vaccination on the un-vaccinated high-contact population of age30e39 to reduce the cumulative cases,and is stable with different basic reproductionnumbers(R_(0)).As for minimizing hospitalization and fatality,the optimized strategy requires vaccination on the un-vaccinated of both aged 30e39 of high contact frequencyand the vulnerable older.Conclusion:The objective of reducing transmission requires vaccination in age groups ofthe highest contact frequency,with more priority for un-vaccinated than un-fully or fullyvaccinated.The objective of reducing total hospitalization and fatality requires not only toreduce transmission but also to protect the vulnerable older.The priority changes byvaccination progress.For any region,if the local contact pattern is available,then with thevaccination coverage,efficacy,and disease characteristics of relative risks in heterogeneouspopulations,the optimal dose-wise vaccinating process will be obtained and gives hintsfor decision-making.
文摘Under the background of high-speed rail networking, this paper uses the passenger trains, the type and direction of the railway via Hang Yong and its extension road line, to construct adsorption and dependency index among cities, depict the contact pattern between the Hang Yong dual-core and its hinterland, measure the “net effect” that two center cities (Hangzhou, Ningbo) have on their hinterland, and estimate population agglomeration potential and future possible population flows of Zhejiang Province and the main sample cities. The result shows that, compared with Ningbo, Hangzhou has stronger radiation force to the vast majority of sample cities, and the sample cities affected more by Ningbo mainly concentrates in Ningbo-Taizhou-Wenzhou along;in addition, the sample cities such as Hangzhou, Ningbo and so on show better population agglomeration, then the population “scramble” phenomenon between cities has begun to appear.
文摘Background:The pandemic of coronavirus disease 2019(COVID-19)has changed human behavior in areas such as contact patterns and mask-wearing frequency.Exploring human–human contact patterns and mask-wearing habits in high-risk groups is an essential step in fully understanding the transmission of respiratory infection-based diseases.This study had aims to quantify local human–human(H–H)contacts in high-risk groups in representative provinces of China and to explore the occupation-specific assortativity and heterogeneity of social contacts.Methods:Delivery workers,medical workers,preschoolers,and students from Qinghai,Shanghai,and Zhejiang were recruited to complete an online questionnaire that queried general information,logged contacts,and assessed the willingness to wear a mask in different settings.The“group contact”was defined as contact with a group at least 20 individuals.The numbers of contacts across different characteristics were assessed and age-specific contact matrices were established.A generalized additive mixed model was used to analyze the associations between the number of individual contacts and several characteristics.The factors influencing the frequency of mask wearing were evaluated with a logistic regression model.Results:A total of 611,287 contacts were reported by 15,635 participants.The frequency of daily individual contacts averaged 3.14(95%confidence interval:3.13–3.15)people per day,while that of group contacts was 37.90(95%CI:37.20–38.70).Skin-to-skin contact and long-duration contact were more likely to occur at home or among family members.Contact matrices of students were the most assortative(all contacts q-index=0.899,95%CI:0.894–0.904).Participants with larger household sizes reported having more contacts.Higher household income per capita was significantly associated with a greater number of contacts among preschoolers(P_(50,000–99,999)=0.033)and students(P_(10,000–29,999)=0.017).In each of the public places,the frequency of mask wearing was highest for delivery workers.For preschoolers and students with more contacts,the proportion of those who reported always wearing masks was lower(P<0.05)in schools/workplaces and public transportation than preschoolers and students with fewer contacts.Conclusions:Contact screening efforts should be concentrated in the home,school,and workplace after an outbreak of an epidemic,as more than 75%of all contacts,on average,will be found in such places.Efforts should be made to improve the mask-wearing rate and age-specific health promotion measures aimed at reducing transmission for the younger demographic.Age-stratified and occupation-specific social contact research in high-risk groups could help inform policy-making decisions during the post-relaxation period of the COVID-19 pandemic.
基金This study was supported by the Health and Medical Research Fund(HMRF)-Commissioned Research on COVID-19 from the Health Bureau of Hong Kong Special Administrative Region(reference number COVID1903007)the General Research Fund from the University Research Committee(reference number 15603920)the Teaching Development Grant(2022-25)from the Hong Kong Polytechnic University(reference number TDG22-25/VTL-8).
文摘An AI-empowered indoor digital contact-tracing system was developed using a centralized architecture and advanced low-energy Bluetooth technologies for indoor positioning,with careful preservation of privacy and data security.We analyzed the contact pattern data from two RCHs and investigated a COVID-19 outbreak in one study site.To evaluate the effectiveness of the system in containing outbreaks with minimal contacts under quarantine,a simulation study was conducted to compare the impact of different quarantine strategies on outbreak containment within RCHs.The significant difference in contact hours between weekdays and weekends was observed for some pairs of RCH residents and staff during the two-week data collection period.No significant difference between secondary cases and uninfected contacts was observed in a COVID-19 outbreak in terms of their demographics and contact patterns.Simulation results based on the collected contact data indicated that a threshold of accumulative contact hours one or two days prior to diagnosis of the index case could dramatically increase the efficiency of outbreak containment within RCHs by targeted isolation of the close contacts.This study demonstrated the feasibility and efficiency of employing an AI-empowered system in indoor digital contact tracing of outbreaks in RCHs in the post-pandemic era.
基金funding from the National Natural Science Foundation of China(grant 71904104)the China Postdoctoral Science Foundation(grant 2019M650726)+1 种基金funding from Qiushi Foundation,the Resnick Sustainability Institute at California Institute of Technology and the National Natural Science Foundation of China(grant 71874097 and 41921005)DMK gratefully acknowledges the support of the Zaffaroni Family Foundation,the Karsten Family Foundation,and US NSF CyberSEES Grant 1539585 and NSF InFEWS grant DGE 1633740.
文摘COVID-19 has triggered an unprecedented public health crisis and a global economic shock.As countries and cities have transitioned away from strict pandemic restrictions,the most effective reopening strategies may vary significantly based on their demographic characteristics and social contact patterns.In this study,we employed an extended agespecific compartment model that incorporates population mobility to investigate the interaction between population age structure and various containment interventions in New York,Los Angeles,Daegu,and Nairobi e four cities with distinct age distributions that served as local epicenters of the epidemic from January 2020 to March 2021.Our results demonstrated that individual social distancing or quarantine strategies alone cannot effectively curb the spread of infection over a one-year period.However,a combined strategy,including school closure,50%working from home,50%reduction in other mobility,10%quarantine rate,and city lockdown interventions,can effectively suppress the infection.Furthermore,our findings revealed that social-distancing policies exhibit strong age-specific effects,and age-targeted interventions can yield significant spillover benefits.Specifically,reducing contact rates among the population under 20 can prevent 14%,18%,56%,and 99%of infections across all age groups in New York,Los Angeles,Daegu,and Nairobi,respectively,surpassing the effectiveness of policies exclusively targeting adults over 60 years old.In particular,to protect the elderly,it is essential to reduce contacts between the younger population and people of all age groups,especially those over 60 years old.While an older population structure may escalate fatality risk,it might also decrease infection risk.Moreover,a higher basic reproduction number amplifies the impact of an older population structure on the fatality risk of the elderly.The considerable variations in susceptibility,severity,and mobility across age groups underscore the need for targeted interventions to effectively control the spread of COVID-19 and mitigate risks in future pandemics.
基金the NSERC of Canada(RGPIN-2020-06825 and DGECR-2020-00369).
文摘COVID-19 has been prevalent worldwide for about 2 years now and has brought unprecedented challenges to our society.Before vaccines were available,the main disease intervention strategies were non-pharmaceutical.Starting December 2020,in Ontario,Canada,vaccines were approved for administering to vulnerable individuals and gradually expanded to all individuals above the age of 12.As the vaccine coverage reached a satisfactory level among the eligible population,normal social activities resumed and schools reopened starting September 2021.However,when schools reopen for in-person learning,children under the age of 12 are unvaccinated and are at higher risks of contracting the virus.We propose an age-stratified model based on the age and vaccine eligibility of the individuals.We fit our model to the data in Ontario,Canada and obtain a good fitting result.The results show that a relaxed between-group contact rate may trigger future epidemic waves more easily than an increased within-group contact rate.An increasing mixed contact rate of the older group quickly amplifies the daily incidence numbers for both groups whereas an increasing mixed contact rate of the younger group mainly leads to future waves in the younger group alone.The results indicate the importance of accelerating vaccine rollout for younger individuals in mitigating disease spread.
