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Manaus, a city of 2.2 million population, the capital of Amazonas state of Brazil was hit badly by two waves of COVID-19 with more than 10,000 severe acute respiratory syndrome deaths by the end of February 2021. It was estimated that the first wave infected over three quarters of the population in Manaus based on routine blood donor data, and the second wave was largely due to reinfection with a new variant named P1 strain. In this work, we revisit these claims, and discuss biological constraints. In particular, we model the two waves with a two-strain model without a significant proportion of reinfections.
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COVID-19 has brought a significant impact to the global health system, and also opportunities and challenges to epidemiological researches. Theoretical epidemiological models can simulate the process of epidemic in scenarios under different conditions. Therefore, modeling researches can analyze the epidemical trend of COVID-19, predict epidemical risks, and evaluate effects of different control measures and vaccine policies. Theoretical epidemiological modeling researches provide scientific advice for the prevention and control of infectious diseases, and play a crucial role in containing COVID-19 over the past year. In this study, we review the theoretical epidemiological modeling researches on COVID-19 and summarize the role of theoretical epidemiological models in the prevention and control of COVID-19, in order to provide reference for the combination of mathematical modeling and epidemic control.
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Humans , COVID-19 , Communicable Diseases/epidemiology , Models, Theoretical , SARS-CoV-2ABSTRACT
Before the lock-down of Wuhan/Hubei/China, on January 23rd 2020, a large number of individuals infected by COVID-19 moved from the epicenter Wuhan and the Hubei province due to the Spring Festival, resulting in an epidemic in the other provinces including the Shaanxi province. The epidemic scale in Shaanxi was comparatively small and with half of cases being imported from the epicenter. Based on the complete epidemic data including the symptom onset time and transmission chains, we calculate the control reproduction number (1.48-1.69) in Xian. We could also compute the time transition, for each imported or local case, from the latent, to infected, to hospitalized compartment, as well as the effective reproduction number. This calculation enables us to revise our early deterministic transmission model to a stochastic discrete epidemic model with case importation and parameterize it. Our model-based analyses reveal that the newly generated infections decay to zero quickly; the cumulative number of case-driven quarantined individuals via contact tracing stabilize at a manageable level, indicating that the intervention strategies implemented in the Shaanxi province have been effective. Risk analyses, important for the consideration of "resumption of work", show that a large second outbreak is expected if the level of case importation remains at the same level as between January 10th and February 4th 2020. However, if the case importation decreases by 30%, 60% and 90%, the second outbreak if happening will be of small-scale assuming contact tracing and quarantine/isolation remain as effective as before. Finally, we consider the effects of intermittent inflow with a Poisson distribution on the likelihood of multiple outbreaks. We believe the developed methodology and stochastic model provide an important model framework for the evaluation of revising travel restriction rules in the consideration of resuming social-economic activities while managing the disease control with potential case importation.
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We present a timely evaluation of the impact of lockdown on the 2019-nCov epidemic in Hubei province, China. The implementation appears to be effective in reducing about 60% of new infections and deaths, and its effect also appears to be sustainable even after its removal. Delaying its implementation reduces its effectiveness. However, the direct economic cost of such a lockdown remains to be seen and whether the model is replicable in other Chinese regions remains a matter of further investigation.
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We present a timely evaluation of the Chinese 2019-nCov epidemic in its initial phase, where 2019-nCov demonstrates comparable transmissibility but lower fatality rates than SARS and MERS. A quick diagnosis that leads to case isolation and integrated interventions will have a major impact on its future trend. Nevertheless, as China is facing its Spring Festival travel rush and the epidemic has spread beyond its borders, further investigation on its potential spatiotemporal transmission pattern and novel intervention strategies are warranted.
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Since December 2019, the outbreak of COVID-19 in Wuhan has spread rapidly due to population movement during the Spring Festival holidays. Since January 23rd, 2020, the strategies of containment and contact tracing followed by quarantine and isolation has been implemented extensively in mainland China, and the rates of detection and confirmation have been continuously increased, which have effectively suppressed the rapid spread of the epidemic. In the early stage of the outbreak of COVID-19, it is of great practical significance to analyze the transmission risk of the epidemic and evaluate the effectiveness and timeliness of prevention and control strategies by using mathematical models and combining with a small amount of real-time updated multi-source data. On the basis of our previous research, we systematically introduce how to establish the transmission dynamic models in line with current Chinese prevention and control strategies step by step, according to the different epidemic stages and the improvement of the data. By summarized our modelling and assessing ideas, the model formulations vary from autonomous to non-autonomous dynamic systems, the risk assessment index changes from the basic regeneration number to the effective regeneration number, and the epidemic development and assessment evolve from the early SEIHR transmission model-based dynamics to the recent dynamics which are mainly associated with the variation of the isolated and suspected population sizes.
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Objective To explore the epidemiological situation and characteristics of human brucellosis in Jiangsu Province from 2006 to 2017,and to provide scientific evidences for its prevention and control.Methods Using a retrospective study,data of brucellosis epidemic in Jiangsu Province from 2006 to 2017 were collected.The epidemic data of brucellosis and the population data were derived from China Disease Prevention and Control Information System,etiological data of brucellosis from 2011 to 2017 were derived from the surveillance report of brucellosis in Jiangsu Province.The overall incidence of brucellosis,pathogen research and regional,seasonal,and population distribution characteristics of cases were analyzed.Results A total of 607 prevalent cases of brucellosis were reported in Jiangsu Province from 2006 to 2017,with an average annual incidence rate of 0.065/100 000,including 595 incident cases.The number of reported case showed a sharp upward trend in 2011-2017,the incidence rates were in an increasing trend (t =5.623,P ＜ 0.01).A total of 132 Brucella strains were isolated from serum samples in Jiangsu Province in 2011-2017,all of the strains were sheep breeds,of which sheep type 3 accounted for 84.85％ (112/132).The top five cities with annual incidence of brucellosis from 2006 to 2017 were Xuzhou,Lianyungang,Suzhou,Huai'an and Suqian,with the incidence rates of 0.223/100 000,0.210/100 000,0.128/100 000,0.108/100 000 and 0.102/100 000,respectively.Brucellosis cases were distributed in each month,with the 540 cases (90.76％,540/595) from January to September.There were 446 males and 161 females in 607 cases of brucellosis,the sex ratio was 2.77:1.00.A total of 579 cases were reported in the age group of 20-74 years old,accounting for 95.39％.The occupational distribution was mainly peasants,which accounting for 60.13％ (365/607).Conclusions The epidemic situation of human brucellosis in Jiangsu Province is becoming increasingly serious recently.Males and peasants are main incidence population.Thus,we should pay more attention to the livestock quarantine and the surveillance and control of brucellosis cases in high risk population so as to control the epidemic situation of brucellosis effectively.
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Objective To investigate the infection status of HCV in remunerated blood donors and risk factors in Jiangsu province.Methods A Cross-sectional study was conducted among people aged ＞50 years.Questionnaires were used to collect the information about their demographic characteristics and risk behaviors,and venous blood samples were collected from them to detect HCV anti-body,HCV-RNA and other biochemical indicators.EpiData and Stata were used for data entry and statistical analysis.Results The overall HCV sero-prevalence rates were 22.55％ and 61.05％ among remunerated blood donors.Data firom multiple stepwise regression analysis showed that alanine aminotransferase (ALT) (adjusted OR=1.38,95％CI:1.18-1.62) and aspartate aminotransferase (AST) (adjusted OR=l.30,95％CI:1.10-1.54) were associated with the outcomes of HCV infection,and fasting plasma glucose (adjusted OR=1.17,95％CI:1.01-1.35) were associated with HCV RNA viral loads.Conclusion The prevalence of HCV infection in remunerated blood donors was high,clinical ALT,AST and fasting plasma glucose levels were associated with the risk for HCV infection and HCV RNA viral load.
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Objective To investigate the infection status of HCV in remunerated blood donors and risk factors in Jiangsu province.Methods A Cross-sectional study was conducted among people aged ＞50 years.Questionnaires were used to collect the information about their demographic characteristics and risk behaviors,and venous blood samples were collected from them to detect HCV anti-body,HCV-RNA and other biochemical indicators.EpiData and Stata were used for data entry and statistical analysis.Results The overall HCV sero-prevalence rates were 22.55％ and 61.05％ among remunerated blood donors.Data firom multiple stepwise regression analysis showed that alanine aminotransferase (ALT) (adjusted OR=1.38,95％CI:1.18-1.62) and aspartate aminotransferase (AST) (adjusted OR=l.30,95％CI:1.10-1.54) were associated with the outcomes of HCV infection,and fasting plasma glucose (adjusted OR=1.17,95％CI:1.01-1.35) were associated with HCV RNA viral loads.Conclusion The prevalence of HCV infection in remunerated blood donors was high,clinical ALT,AST and fasting plasma glucose levels were associated with the risk for HCV infection and HCV RNA viral load.
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<p><b>BACKGROUND</b>Over the past two decades, the clinical presentation of renal masses has evolved, where the rising incidence of small renal masses (SRMs) and concomitant minimal invasive treatments have led to noteworthy changes in paradigm of kidney cancer. This study was to perform a proportional meta-analysis of observational studies on perioperative complications and oncological outcomes of partial nephrectomy (PN) and radiofrequency ablation (RFA).</p><p><b>METHODS</b>The US National Library of Medicine's life science database (Medline) and the Web of Science were exhaustly searched before August 1, 2013. Clinical stage 1 SRMs that were treated with PN or RFA were included, and perioperative complications and oncological outcomes of a total of 9 565 patients were analyzed.</p><p><b>RESULTS</b>Patients who underwent RFA were significantly older (P < 0.001). In the subanalysis of stage T1 tumors, the major complication rate of PN was greater than that of RFA (laparoscopic partial nephrectomy (LPN)/robotic partial nephrectomy (RPN): 7.2%, open partial nephrectomy (OPN): 7.9%, RFA: 3.1%, both P < 0.001). Minor complications occurred more frequently after RFA (RFA: 13.8%, LPN/RPN: 7.5%, OPN: 9.5%, both P < 0.001). By multivariate analysis, the relative risks for minor complications of RFA, compared with LPN and OPN, were 1.7-fold and 1.5-fold greater (both P < 0.01), respectively. Patients treated with RFA had a greater local progression rate than those treated by PN (RFA: 4.6%, LPN/RPN: 1.2%, OPN: 1.9%, both P < 0.001). By multivariate analysis, the local tumor progression for RFA versus LPN/RPN and OPN were 4.5-fold and 3.1-fold greater, respectively (both P < 0.001).</p><p><b>CONCLUSIONS</b>The current data illustrate that both PN and RFA are viable strategies for the treatment of SRMs. Compared with PN, RFA showed a greater risk of local tumor progression but a lower major complication rate, which is considered better for poor candidates. PN is with no doubt the golden treatment for SRMs, and LPN has been widely accepted as the first option for nephron-sparing surgery by experienced urologists. RFA may be the best option for select patients with significant comorbidity.</p>
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Humans , Catheter Ablation , Methods , Kidney Neoplasms , General Surgery , Therapeutics , Nephrectomy , MethodsABSTRACT
<p><b>OBJECTIVE</b>The migrant population is a vulnerable group for HIV infection in China. Understanding potential epidemic trends among migrants is critical for developing HIV preventative measures in this population.</p><p><b>METHODS</b>The Estimation and Projection Package (EPP) model was used to process prefecture and county-level surveillance data to generate HIV prevalence and epidemic trends for migrant populations in China.</p><p><b>RESULTS</b>The prevalence of HIV among migrants in 2009 was estimated at 0.075% (95% CI: 0.042%, 0.108%) in China. The HIV epidemic among migrants is likely to increase over the next 5 years, with the prevalence expected to reach 0.110% (95% CI: 0.070%, 0.150%) by 2015.</p><p><b>CONCLUSION</b>Although the 2009 estimates for the HIV/AIDS epidemic in China indicate a slower rate of increase compared with the national HIV/AIDS epidemic, it is estimated to persistently increase among migrants over the next 5 years. Migrants will have a strong impact on the overall future of the HIV epidemic trend in China and evidence-based prevention and monitoring efforts should be expanded for this vulnerable population.</p>
