Japanese encephalitis(JE),a vector-borne disease caused by the Japanese encephalitis virus(JEV),remains a major public health concern in South and Southeast Asia[1].JEV,a Flaviviridae family virus,is primarily transmi...Japanese encephalitis(JE),a vector-borne disease caused by the Japanese encephalitis virus(JEV),remains a major public health concern in South and Southeast Asia[1].JEV,a Flaviviridae family virus,is primarily transmitted by Culex mosquitoes,especially the Culex vishnui subgroup,which breeds extensively in rice fields[1].Birds(Ardeidae family)act as natural reservoirs,while pigs serve as amplifying hosts,and humans are incidental hosts[1].展开更多
COVID-19 vaccine-induced protection declines over time.This waning of immunity has been described in modelling as a lower level of protection.This study incorporated finescale vaccine waning into modelling to predict ...COVID-19 vaccine-induced protection declines over time.This waning of immunity has been described in modelling as a lower level of protection.This study incorporated finescale vaccine waning into modelling to predict the next surge of the Omicron variant of the SARS-CoV-2 virus.In Hong Kong,the Omicron subvariant BA.2 caused a significant epidemic wave between February and April 2022,which triggered high vaccination rates.About half a year later,a second outbreak,dominated by a combination of BA.2,BA.4 and BA.5 subvariants,began to spread.We developed mathematical equations to formulate continuous changes in vaccine boosting and waning based on empirical serological data.These equations were incorporated into a multi-strain discrete-time Susceptible-Exposed-Infectious-Removed model.The daily number of reported cases during the first Omicron outbreak,with daily vaccination rates,the population mobility index and daily average temperature,were used to train the model.The model successfully predicted the size and timing of the second surge and the variant replacement by BA.4/5.It estimated 655,893 cumulative reported cases from June 1,2022 to 31 October 2022,which was only 2.69%fewer than the observed cumulative number of 674,008.The model projected that increased vaccine protection(by larger vaccine coverage or no vaccine waning)would reduce the size of the second surge of BA.2 infections substantially but would allow more subsequent BA.4/5 infections.Increased vaccine coverage or greater vaccine protection can reduce the infection rate during certain periods when the immune-escape variants cocirculate;however,new immune-escape variants spread more by out-competing the previous strain.展开更多
In this research,we introduce a comprehensive epidemiological model that accounts for multiple strains of an infectious disease and two distinct vaccination options.Vaccination stands out as the most effective means t...In this research,we introduce a comprehensive epidemiological model that accounts for multiple strains of an infectious disease and two distinct vaccination options.Vaccination stands out as the most effective means to prevent and manage infectious diseases.However,when there are various vaccines available,each with its costs and effectiveness,the decision-making process for individuals becomes paramount.Furthermore,the factor of waning immunity following vaccination also plays a significant role in influencing these choices.To understand how individuals make decisions in the context of multiple strains and waning immunity,we employ a behavioral model,allowing an epidemiological model to be coupled with the dynamics of a decision-making process.Individuals base their choice of vaccination on factors such as the total number of infected individuals and the cost-effectiveness of the vaccine.Our findings indicate that as waning immunity increases,people tend to prioritize vaccines with higher costs and greater efficacy.Moreover,when more contagious strains are present,the equilibrium in vaccine adoption is reached more rapidly.Finally,we delve into the social dilemma inherent in our model by quantifying the social efficiency deficit(SED)under various parameter combinations.展开更多
In the spread of infectious diseases,intervention levels play a crucial role in shaping interactions between healthy and infected individuals,leading to a nonlinear transmission process.Additionally,the availability o...In the spread of infectious diseases,intervention levels play a crucial role in shaping interactions between healthy and infected individuals,leading to a nonlinear transmission process.Additionally,the availability of medical resources limits the recovery rate of infected patients,adding further nonlinear dynamics to the healing process.Our research introduces novelty by combining nonlinear incidence and recovery rates alongside waning immunity in an epidemic model.We present a modified SIRW-type model,examining the epidemic problem with these factors.Through analysis,we explore conditions for non-endemic and co-existing cases based on the basic reproduction ratio.The local stability of equilibria is verified using the Routh-Hurwitz criteria,while global stability is assessed using Lyapunov functions for each equilibrium.Furthermore,we investigate bifurcations around both non-endemic and co-existing equilibria.Numerically,we give some simulations to support our analytical findings.展开更多
The global dynamics of an SVEIR epidemic model with age-dependent waning immu- nity, latency and relapse are studied. Sharp threshold properties for global asymptotic stability of both disease-free equilibrium and end...The global dynamics of an SVEIR epidemic model with age-dependent waning immu- nity, latency and relapse are studied. Sharp threshold properties for global asymptotic stability of both disease-free equilibrium and endemic equilibrium are given. The asymptotic smoothness, uniform persistence and the existence of interior global attractor of the semi-flow generated by a family of solutions of the system are also addressed. Furthermore, some related strategies for controlling the spread of diseases are discussed.展开更多
The incidence of Japanese encephalitis(JE)has significantly decreased in China due to JE vaccines.In this study,we investigated the post-JE vaccination seroprevalence and protection provided by vaccinated sera against...The incidence of Japanese encephalitis(JE)has significantly decreased in China due to JE vaccines.In this study,we investigated the post-JE vaccination seroprevalence and protection provided by vaccinated sera against Japanese encephalitis virus(JEV)to elucidate the persistence and waning of antibodies to JEV among JE-SA14-14-2-vaccinated children.A total of 300 serum samples were collected from vaccinated children aged 3-10 years in Zhaotong,Yunnan,China.The seroprevalence of anti-JEV antibodies was determined by enzyme-linked immune sorbent assay and plaque reduction neutralization test.The highest seropositivity of 82%was observed in vaccinated children during the first 0.5-1.5 years after booster vaccination.Then,the seropositivity began to decline and remained lower than the original level observed in the 0.5-1.5-year group.An association was found between the waning of seroprevalence and elapsed time of the post-booster vaccination.Similarly,the neutralizing antibody(nAb)titres gradually decreased over time,and the levels showed a positive correlation with the protective efficacy in mice.This finding suggests that nAbs play an important role in the antiviral process and that the nAb titre is an adequately credible parameter for evaluating the protective efficacy induced by the JE vaccine.Our results provide data that clarify the persistence and waning of antibodies to JEV,which may help elucidate the pathogenesis of JE.展开更多
“Oft expectation fails and most oft there Where most it promises,and oft it hits Where hope is coldest and despair most fits.”1—William Shakespeare(1564–1616),All’s Well That Ends Well Not feeling ready to enter ...“Oft expectation fails and most oft there Where most it promises,and oft it hits Where hope is coldest and despair most fits.”1—William Shakespeare(1564–1616),All’s Well That Ends Well Not feeling ready to enter winter quite yet,we start this month’s editorial with a reflection on the beauty of the waning fall season(and the chemistry hidden within).Nature is at its most brilliant in the fall,as the varied green foliage of summer turns yellow.展开更多
As public health policies shifted in 2023 from emergency response to long-term COVID-19 disease management,immunization programs started to face the challenge of formulating routine booster campaigns in a still highly...As public health policies shifted in 2023 from emergency response to long-term COVID-19 disease management,immunization programs started to face the challenge of formulating routine booster campaigns in a still highly uncertain seasonal behavior of the COVID-19 epidemic.Mathematical models assessing past booster campaigns and integrating knowledge on waning of immunity can help better inform current and future vaccination programs.Focusing on the first booster campaign in the 2021/2022 winter in France,we used a multi-strain age-stratified transmission model to assess the effectiveness of the observed booster vaccination in controlling the succession of Delta,Omicron BA.1 and BA.2 waves.We explored counterfactual scenarios altering the eligibility criteria and inter-dose delay.Our study showed that the success of the immunization program in curtailing the Omicron BA.1 and BA.2 waves was largely dependent on the inclusion of adults among the eligible groups,and was highly sensitive to the inter-dose delay,which was changed over time.Shortening or prolonging this delay,even by only one month,would have required substantial social distancing interventions to curtail the hospitalization peak.Also,the time window for adjusting the delay was very short.Our findings highlight the importance of readiness and adaptation in the formulation of routine booster campaign in the current level of epidemiological uncertainty.展开更多
Coronavirus Disease(COVID-19),which began as a small outbreak in Wuhan,China,in December 2019,became a global pandemic within months due to its high transmissibility.In the absence of pharmaceutical treatment,various ...Coronavirus Disease(COVID-19),which began as a small outbreak in Wuhan,China,in December 2019,became a global pandemic within months due to its high transmissibility.In the absence of pharmaceutical treatment,various non-pharmaceutical interventions(NPIs)to contain the spread of COVID-19 brought the entire world to a halt.After almost a year of seemingly returning to normalcy with the world's quickest vaccine development,the emergence of more infectious and vaccine resistant coronavirus variants is bringing the situation back to where it was a year ago.In the light of this new situation,we conducted a study to portray the possible scenarios based on the three key factors:impact of interventions(pharmaceutical and NPIs),vaccination rate,and vaccine efficacy.In our study,we assessed two of the most crucial factors,transmissibility and vaccination rate,in order to reduce the spreading of COVID-19 in a simple but effective manner.In order to incorporate the time-varying mutational landscape of COVID-19 variants,we estimated a weighted transmissibility composed of the proportion of existing strains that naturally vary over time.Additionally,we consider time varying vaccination rates based on the number of daily new cases.Our method for calculating the vaccination rate from past active cases is an effective approach in forecasting probable future scenarios as it actively tracks people's attitudes toward immunization as active case changes.Our simulations show that if a large number of individuals cannot be vaccinated by ensuring high efficacy in a short period of time,adopting NPIs is the best approach to manage disease transmission with the emergence of new vaccine breakthrough and more infectious variants.展开更多
In some disease systems,the process of waning immunity can be subtle,involving a complex relationship between the duration of immunitydacquired either through natural infection or vaccinationdand subsequent boosting o...In some disease systems,the process of waning immunity can be subtle,involving a complex relationship between the duration of immunitydacquired either through natural infection or vaccinationdand subsequent boosting of immunity through asymptomatic reexposure.We present and analyse a model of infectious disease transmission where primary and secondary infections are distinguished to examine the interplay between infection and immunity.Additionally we allow the duration of infection-acquired immunity to differ from that of vaccine-acquired immunity to explore the impact on long-term disease patterns and prevalence of infection in the presence of immune boosting.Our model demonstrates that vaccination may induce cyclic behaviour,and the ability of vaccinations to reduce primary infections may not lead to decreased transmission.Where the boosting of vaccine-acquired immunity delays a primary infection,the driver of transmission largely remains primary infections.In contrast,if the immune boosting bypasses a primary infection,secondary infections become the main driver of transmission under a sufficiently long duration of immunity.Our results show that the epidemiological patterns of an infectious disease may change considerably when the duration of vaccine-acquired immunity differs from that of infection-acquired immunity.Our study highlights that for any particular disease and associated vaccine,a detailed understanding of the waning and boosting of immunity and how the duration of protection is influenced by infection prevalence are important as we seek to optimise vaccination strategies.展开更多
文摘Japanese encephalitis(JE),a vector-borne disease caused by the Japanese encephalitis virus(JEV),remains a major public health concern in South and Southeast Asia[1].JEV,a Flaviviridae family virus,is primarily transmitted by Culex mosquitoes,especially the Culex vishnui subgroup,which breeds extensively in rice fields[1].Birds(Ardeidae family)act as natural reservoirs,while pigs serve as amplifying hosts,and humans are incidental hosts[1].
基金support from grants funded by the City University of Hong Kong[#7005523,#7005748 and#7005876]the General Research Fund[#11203823]from the Research Grants Council of Hong Kong。
文摘COVID-19 vaccine-induced protection declines over time.This waning of immunity has been described in modelling as a lower level of protection.This study incorporated finescale vaccine waning into modelling to predict the next surge of the Omicron variant of the SARS-CoV-2 virus.In Hong Kong,the Omicron subvariant BA.2 caused a significant epidemic wave between February and April 2022,which triggered high vaccination rates.About half a year later,a second outbreak,dominated by a combination of BA.2,BA.4 and BA.5 subvariants,began to spread.We developed mathematical equations to formulate continuous changes in vaccine boosting and waning based on empirical serological data.These equations were incorporated into a multi-strain discrete-time Susceptible-Exposed-Infectious-Removed model.The daily number of reported cases during the first Omicron outbreak,with daily vaccination rates,the population mobility index and daily average temperature,were used to train the model.The model successfully predicted the size and timing of the second surge and the variant replacement by BA.4/5.It estimated 655,893 cumulative reported cases from June 1,2022 to 31 October 2022,which was only 2.69%fewer than the observed cumulative number of 674,008.The model projected that increased vaccine protection(by larger vaccine coverage or no vaccine waning)would reduce the size of the second surge of BA.2 infections substantially but would allow more subsequent BA.4/5 infections.Increased vaccine coverage or greater vaccine protection can reduce the infection rate during certain periods when the immune-escape variants cocirculate;however,new immune-escape variants spread more by out-competing the previous strain.
基金This study received financial support in the form of a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science(JSPS),specifically through KAKENHI(Grant No.JP 23H03499).
文摘In this research,we introduce a comprehensive epidemiological model that accounts for multiple strains of an infectious disease and two distinct vaccination options.Vaccination stands out as the most effective means to prevent and manage infectious diseases.However,when there are various vaccines available,each with its costs and effectiveness,the decision-making process for individuals becomes paramount.Furthermore,the factor of waning immunity following vaccination also plays a significant role in influencing these choices.To understand how individuals make decisions in the context of multiple strains and waning immunity,we employ a behavioral model,allowing an epidemiological model to be coupled with the dynamics of a decision-making process.Individuals base their choice of vaccination on factors such as the total number of infected individuals and the cost-effectiveness of the vaccine.Our findings indicate that as waning immunity increases,people tend to prioritize vaccines with higher costs and greater efficacy.Moreover,when more contagious strains are present,the equilibrium in vaccine adoption is reached more rapidly.Finally,we delve into the social dilemma inherent in our model by quantifying the social efficiency deficit(SED)under various parameter combinations.
基金funded by Universitas Padjadjaran,Indonesia,via Hibah Riset Data Pustaka dan Daring Universitas Padjadjaran,No.1549/UN6.3.1/PT.00/2023.
文摘In the spread of infectious diseases,intervention levels play a crucial role in shaping interactions between healthy and infected individuals,leading to a nonlinear transmission process.Additionally,the availability of medical resources limits the recovery rate of infected patients,adding further nonlinear dynamics to the healing process.Our research introduces novelty by combining nonlinear incidence and recovery rates alongside waning immunity in an epidemic model.We present a modified SIRW-type model,examining the epidemic problem with these factors.Through analysis,we explore conditions for non-endemic and co-existing cases based on the basic reproduction ratio.The local stability of equilibria is verified using the Routh-Hurwitz criteria,while global stability is assessed using Lyapunov functions for each equilibrium.Furthermore,we investigate bifurcations around both non-endemic and co-existing equilibria.Numerically,we give some simulations to support our analytical findings.
基金X. Liu is supported by the National Natural Science Foundation of China （11271303）. L. Liu is supported by the National Natural Science Foundation of China （11601293） and Chongqing Graduate Student Research Innovation Project （CYB14053）. We are grateful to the editors and two anonymous referees for their valuable comments and suggestions that led to an improvement of our manuscript.
文摘The global dynamics of an SVEIR epidemic model with age-dependent waning immu- nity, latency and relapse are studied. Sharp threshold properties for global asymptotic stability of both disease-free equilibrium and endemic equilibrium are given. The asymptotic smoothness, uniform persistence and the existence of interior global attractor of the semi-flow generated by a family of solutions of the system are also addressed. Furthermore, some related strategies for controlling the spread of diseases are discussed.
基金supported by grants from the National Natural Science Foundation of China (81471957, 81772172, 81671971, U1602223 and 81871641)a grant from the Open Research Projects of Key Laboratory of Beijing Ditan Hospital, Capital Medical University (DTKF201705)
文摘The incidence of Japanese encephalitis(JE)has significantly decreased in China due to JE vaccines.In this study,we investigated the post-JE vaccination seroprevalence and protection provided by vaccinated sera against Japanese encephalitis virus(JEV)to elucidate the persistence and waning of antibodies to JEV among JE-SA14-14-2-vaccinated children.A total of 300 serum samples were collected from vaccinated children aged 3-10 years in Zhaotong,Yunnan,China.The seroprevalence of anti-JEV antibodies was determined by enzyme-linked immune sorbent assay and plaque reduction neutralization test.The highest seropositivity of 82%was observed in vaccinated children during the first 0.5-1.5 years after booster vaccination.Then,the seropositivity began to decline and remained lower than the original level observed in the 0.5-1.5-year group.An association was found between the waning of seroprevalence and elapsed time of the post-booster vaccination.Similarly,the neutralizing antibody(nAb)titres gradually decreased over time,and the levels showed a positive correlation with the protective efficacy in mice.This finding suggests that nAbs play an important role in the antiviral process and that the nAb titre is an adequately credible parameter for evaluating the protective efficacy induced by the JE vaccine.Our results provide data that clarify the persistence and waning of antibodies to JEV,which may help elucidate the pathogenesis of JE.
文摘“Oft expectation fails and most oft there Where most it promises,and oft it hits Where hope is coldest and despair most fits.”1—William Shakespeare(1564–1616),All’s Well That Ends Well Not feeling ready to enter winter quite yet,we start this month’s editorial with a reflection on the beauty of the waning fall season(and the chemistry hidden within).Nature is at its most brilliant in the fall,as the varied green foliage of summer turns yellow.
基金funded by:Agence Nationale de la Recherche project DATAREDUX(ANR-19-CE46-0008-03)to VCANRSeMaladies InfectieusesEmergentes project EMERGEN(ANRS0151)to VC+2 种基金Horizon Europe grant ESCAPE(101095619)to VCEU HORIZON grant VERDI(101045989)EU Horizon 2020 grant MOOD(H2020-874850)to VC.The study is catalogued as MOOD105。
文摘As public health policies shifted in 2023 from emergency response to long-term COVID-19 disease management,immunization programs started to face the challenge of formulating routine booster campaigns in a still highly uncertain seasonal behavior of the COVID-19 epidemic.Mathematical models assessing past booster campaigns and integrating knowledge on waning of immunity can help better inform current and future vaccination programs.Focusing on the first booster campaign in the 2021/2022 winter in France,we used a multi-strain age-stratified transmission model to assess the effectiveness of the observed booster vaccination in controlling the succession of Delta,Omicron BA.1 and BA.2 waves.We explored counterfactual scenarios altering the eligibility criteria and inter-dose delay.Our study showed that the success of the immunization program in curtailing the Omicron BA.1 and BA.2 waves was largely dependent on the inclusion of adults among the eligible groups,and was highly sensitive to the inter-dose delay,which was changed over time.Shortening or prolonging this delay,even by only one month,would have required substantial social distancing interventions to curtail the hospitalization peak.Also,the time window for adjusting the delay was very short.Our findings highlight the importance of readiness and adaptation in the formulation of routine booster campaign in the current level of epidemiological uncertainty.
基金supported by the National Science Foundation under the Grant No.(DMS-1815750).
文摘Coronavirus Disease(COVID-19),which began as a small outbreak in Wuhan,China,in December 2019,became a global pandemic within months due to its high transmissibility.In the absence of pharmaceutical treatment,various non-pharmaceutical interventions(NPIs)to contain the spread of COVID-19 brought the entire world to a halt.After almost a year of seemingly returning to normalcy with the world's quickest vaccine development,the emergence of more infectious and vaccine resistant coronavirus variants is bringing the situation back to where it was a year ago.In the light of this new situation,we conducted a study to portray the possible scenarios based on the three key factors:impact of interventions(pharmaceutical and NPIs),vaccination rate,and vaccine efficacy.In our study,we assessed two of the most crucial factors,transmissibility and vaccination rate,in order to reduce the spreading of COVID-19 in a simple but effective manner.In order to incorporate the time-varying mutational landscape of COVID-19 variants,we estimated a weighted transmissibility composed of the proportion of existing strains that naturally vary over time.Additionally,we consider time varying vaccination rates based on the number of daily new cases.Our method for calculating the vaccination rate from past active cases is an effective approach in forecasting probable future scenarios as it actively tracks people's attitudes toward immunization as active case changes.Our simulations show that if a large number of individuals cannot be vaccinated by ensuring high efficacy in a short period of time,adopting NPIs is the best approach to manage disease transmission with the emergence of new vaccine breakthrough and more infectious variants.
基金Tiffany Leung is supported by a Melbourne International Research Scholarship from the University of Melbourne and a National Health and Medical Research Council(NHMRC)funded Centre for Research Excellence in Infectious Diseases Modelling to Inform Public Health Policy(1078068).
文摘In some disease systems,the process of waning immunity can be subtle,involving a complex relationship between the duration of immunitydacquired either through natural infection or vaccinationdand subsequent boosting of immunity through asymptomatic reexposure.We present and analyse a model of infectious disease transmission where primary and secondary infections are distinguished to examine the interplay between infection and immunity.Additionally we allow the duration of infection-acquired immunity to differ from that of vaccine-acquired immunity to explore the impact on long-term disease patterns and prevalence of infection in the presence of immune boosting.Our model demonstrates that vaccination may induce cyclic behaviour,and the ability of vaccinations to reduce primary infections may not lead to decreased transmission.Where the boosting of vaccine-acquired immunity delays a primary infection,the driver of transmission largely remains primary infections.In contrast,if the immune boosting bypasses a primary infection,secondary infections become the main driver of transmission under a sufficiently long duration of immunity.Our results show that the epidemiological patterns of an infectious disease may change considerably when the duration of vaccine-acquired immunity differs from that of infection-acquired immunity.Our study highlights that for any particular disease and associated vaccine,a detailed understanding of the waning and boosting of immunity and how the duration of protection is influenced by infection prevalence are important as we seek to optimise vaccination strategies.
