This article focuses on the study of an age structured SEIRS epidemic model with a vaccination program when the total population size is not kept at constant. We first give the explicit expression of the reproduction ...This article focuses on the study of an age structured SEIRS epidemic model with a vaccination program when the total population size is not kept at constant. We first give the explicit expression of the reproduction number in the presence of vaccine ( is the exponent of growth of total population), and show that the infection-free steady state is linearly stable if and unstable if , then we apply the theoretical results to vaccination policies to determine the optimal age or ages at which an individual should be vaccinated. It is shown that the optimal strategy can be either one- or two-age strategies.展开更多
Background:China is facing substantial risks of imported coronavirus disease 2019(COVID-19)cases and a domestic resurgence in the long run,and COVID-19 vaccination is expected to be the long-lasting solution to end th...Background:China is facing substantial risks of imported coronavirus disease 2019(COVID-19)cases and a domestic resurgence in the long run,and COVID-19 vaccination is expected to be the long-lasting solution to end the pandemic.We aim to estimate the size of the target population for COVID-19 vaccination at the provincial level in the mainland of China,and summarize the current progress of vaccination programs,which could support local governments in the timely determination and adjustment of vaccination policies and promotional measures.Methods:We conducted a descriptive study of the entire population in the mainland of China,between December 2020 and August 2021.By extracting provincial-stratifed data from publicly available sources,we estimated the size of priority target groups for vaccination programs,and further characterized the ongoing vaccination program at the provincial level,including the total doses administered,the coverage rate,and the vaccination capacity needed to achieve the target coverage of 80%by the end of 2021.We used R(version 4.1.0)to complete the descriptive statistics.Results:The size of the target population shows large diferences among provinces,ranging from 3.4 million to 108.4 million.As of 31 August,2021,the speed of vaccine roll-out difers considerably as well,with the highest coverage occurring in Beijing and Shanghai,where 88.5%and 79.1%of the population has been fully vaccinated,respectively.In 22 of 31 provincial-level administrative divisions(PLADs),more than 70%of the population was administered at least one dose by August.With the current vaccination capacity,the target of 80%coverage could be achieved by 2021 in 28 PLADs.Conclusions:Disparities exist in the target population size and vaccination progress across provinces in the mainland of China.China has made great strides in the vaccination speed since roll-out,and could basically achieve the targeted vaccine coverage.展开更多
BACKGROUND Varicella(chickenpox)and herpes zoster(shingles)are outcomes of varicella-zoster virus(VZV)infection,and understanding their incidence trends is vital for public health planning.AIM To conduct an ambispecti...BACKGROUND Varicella(chickenpox)and herpes zoster(shingles)are outcomes of varicella-zoster virus(VZV)infection,and understanding their incidence trends is vital for public health planning.AIM To conduct an ambispective epidemiological study by analyzing the main epidemiological characteristics of VZV infection during an 18 year-period(2000-2018).METHODS We used descriptive and epidemiological methods to characterize chickenpox in Bulgaria,the city of Plovdiv and the region for a period of 18 years(2000-2018).RESULTS The average incidence of varicella-zoster infection for the period 2000–2018 in the Plovdiv region was estimated at 449.58‰.The highest relative share of the infection was assessed in the month of January at 13.6%,and the lowest in the months of August and September at 2.9%(both months).The age group most affected by the infection was 1-4 years,followed by 5-9 years.This corresponds to the so-called"pro-epidemic population"-a phenomenon typical for airborne infections,confirming their mass impact on the perpetuation of VZV infection.CONCLUSION Our findings reveal significant insights into VZV epidemiology,including age-specific incidence rates,clinical manifestations,and vaccination impact.This comprehensive analysis contributes to the broader understanding of VZV infec-tion dynamics and may inform evidence-based preventive measures.展开更多
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the resulting coronavirus disease 2019 (COVID-19) have a substantial burden on health-care systems around the world. This is a ran...Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the resulting coronavirus disease 2019 (COVID-19) have a substantial burden on health-care systems around the world. This is a randomized parallel controlled trial for assessment of the immunogenicity and safety of an inactivated SARS-CoV-2 vaccine, aiming to determine an appropriate vaccination interval of the vaccine for high-risk occupational population.Methods: In an ongoing randomized, parallel, controlled phase IV trial between January and May 2021 in Taiyuan City, Shanxi Province, China, we randomly assigned the airport ground staff and public security officers aged 18 to 59 years to receive two doses of inactivated SARS-CoV-2 vaccine at 14 days, 21 days, or 28 days. The serum neutralizing antibody to live SARS-CoV-2 was performed at baseline and 28 days after immunization. Long-term data are being collected. The primary immunogenicity endpoints were neutralization antibody seroconversion and geometric mean titer (GMT) at 28 days after the second dose. Analysis of variance (ANOVA), chi-square, and logistic regression analysis were used for data analysis.Results: A total of 809 participants underwent randomization and received two doses of injections: 270, 270, 269 in the 0-14, 0-21, and 0-28 vaccination group, respectively. By day 28 after the second injection, SARS-CoV-2 neutralizing antibody of GMT was 98.4 (95%CI: 88.4-108.4) in the 0-14 group, which was significantly lower compared with 134.4 (95%CI: 123.1-145.7) in the 0-21 group (P < 0.001 vs 0-14 group) and 145.5 (95%CI: 131.3-159.6) in the 0-28 group (P < 0.001 vs 0-14 group), resulting in the seroconversion rates to neutralizing antibodies (GMT ≥ 16) of 100.0% for all three groups, respectively. The intention-to-treat (ITT) analysis yielded similar results. All reported adverse reactions were mild.Conclusions: Both a two-dose of inactivated SARS-CoV-2 vaccine at 0-21 days and 0-28 days regimens significantly improved SARS-CoV-2 neutralizing antibody level compared to the 0-14 days regimen in high-risk occupational population, with seroconversion rates of 100.0%.展开更多
基金Supported by the NSFC (No.10371105) and the NSF of Henan Province (No.0312002000No.0211044800)
文摘This article focuses on the study of an age structured SEIRS epidemic model with a vaccination program when the total population size is not kept at constant. We first give the explicit expression of the reproduction number in the presence of vaccine ( is the exponent of growth of total population), and show that the infection-free steady state is linearly stable if and unstable if , then we apply the theoretical results to vaccination policies to determine the optimal age or ages at which an individual should be vaccinated. It is shown that the optimal strategy can be either one- or two-age strategies.
文摘Background:China is facing substantial risks of imported coronavirus disease 2019(COVID-19)cases and a domestic resurgence in the long run,and COVID-19 vaccination is expected to be the long-lasting solution to end the pandemic.We aim to estimate the size of the target population for COVID-19 vaccination at the provincial level in the mainland of China,and summarize the current progress of vaccination programs,which could support local governments in the timely determination and adjustment of vaccination policies and promotional measures.Methods:We conducted a descriptive study of the entire population in the mainland of China,between December 2020 and August 2021.By extracting provincial-stratifed data from publicly available sources,we estimated the size of priority target groups for vaccination programs,and further characterized the ongoing vaccination program at the provincial level,including the total doses administered,the coverage rate,and the vaccination capacity needed to achieve the target coverage of 80%by the end of 2021.We used R(version 4.1.0)to complete the descriptive statistics.Results:The size of the target population shows large diferences among provinces,ranging from 3.4 million to 108.4 million.As of 31 August,2021,the speed of vaccine roll-out difers considerably as well,with the highest coverage occurring in Beijing and Shanghai,where 88.5%and 79.1%of the population has been fully vaccinated,respectively.In 22 of 31 provincial-level administrative divisions(PLADs),more than 70%of the population was administered at least one dose by August.With the current vaccination capacity,the target of 80%coverage could be achieved by 2021 in 28 PLADs.Conclusions:Disparities exist in the target population size and vaccination progress across provinces in the mainland of China.China has made great strides in the vaccination speed since roll-out,and could basically achieve the targeted vaccine coverage.
基金the European Union-NextGenerationEU,through the National Recovery and Resilience Plan of the Republic of Bulgaria,No.BG-RRP-2.004-0008.
文摘BACKGROUND Varicella(chickenpox)and herpes zoster(shingles)are outcomes of varicella-zoster virus(VZV)infection,and understanding their incidence trends is vital for public health planning.AIM To conduct an ambispective epidemiological study by analyzing the main epidemiological characteristics of VZV infection during an 18 year-period(2000-2018).METHODS We used descriptive and epidemiological methods to characterize chickenpox in Bulgaria,the city of Plovdiv and the region for a period of 18 years(2000-2018).RESULTS The average incidence of varicella-zoster infection for the period 2000–2018 in the Plovdiv region was estimated at 449.58‰.The highest relative share of the infection was assessed in the month of January at 13.6%,and the lowest in the months of August and September at 2.9%(both months).The age group most affected by the infection was 1-4 years,followed by 5-9 years.This corresponds to the so-called"pro-epidemic population"-a phenomenon typical for airborne infections,confirming their mass impact on the perpetuation of VZV infection.CONCLUSION Our findings reveal significant insights into VZV epidemiology,including age-specific incidence rates,clinical manifestations,and vaccination impact.This comprehensive analysis contributes to the broader understanding of VZV infec-tion dynamics and may inform evidence-based preventive measures.
基金The study was supported by the COVID-19 Project of Shanxi Provincial Finance, and the Project of Shanxi Provincial Key Laboratory for major infectious disease response.
文摘Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the resulting coronavirus disease 2019 (COVID-19) have a substantial burden on health-care systems around the world. This is a randomized parallel controlled trial for assessment of the immunogenicity and safety of an inactivated SARS-CoV-2 vaccine, aiming to determine an appropriate vaccination interval of the vaccine for high-risk occupational population.Methods: In an ongoing randomized, parallel, controlled phase IV trial between January and May 2021 in Taiyuan City, Shanxi Province, China, we randomly assigned the airport ground staff and public security officers aged 18 to 59 years to receive two doses of inactivated SARS-CoV-2 vaccine at 14 days, 21 days, or 28 days. The serum neutralizing antibody to live SARS-CoV-2 was performed at baseline and 28 days after immunization. Long-term data are being collected. The primary immunogenicity endpoints were neutralization antibody seroconversion and geometric mean titer (GMT) at 28 days after the second dose. Analysis of variance (ANOVA), chi-square, and logistic regression analysis were used for data analysis.Results: A total of 809 participants underwent randomization and received two doses of injections: 270, 270, 269 in the 0-14, 0-21, and 0-28 vaccination group, respectively. By day 28 after the second injection, SARS-CoV-2 neutralizing antibody of GMT was 98.4 (95%CI: 88.4-108.4) in the 0-14 group, which was significantly lower compared with 134.4 (95%CI: 123.1-145.7) in the 0-21 group (P < 0.001 vs 0-14 group) and 145.5 (95%CI: 131.3-159.6) in the 0-28 group (P < 0.001 vs 0-14 group), resulting in the seroconversion rates to neutralizing antibodies (GMT ≥ 16) of 100.0% for all three groups, respectively. The intention-to-treat (ITT) analysis yielded similar results. All reported adverse reactions were mild.Conclusions: Both a two-dose of inactivated SARS-CoV-2 vaccine at 0-21 days and 0-28 days regimens significantly improved SARS-CoV-2 neutralizing antibody level compared to the 0-14 days regimen in high-risk occupational population, with seroconversion rates of 100.0%.
