scholarly journals Assessing optimal time between doses in two-dose vaccination regimen in an ongoing epidemic of SARS-CoV-2

2021 ◽  
Author(s):  
Leonardo Souto Ferreira ◽  
Otavio Canton ◽  
Rafael Lopes Paixão da Silva ◽  
Silas Poloni ◽  
Vítor Sudbrack ◽  
...  
Keyword(s):  
Production Rate ◽  
Time Window ◽  
Linear Optimization ◽  
Critical Role ◽  
Absolute Number ◽  
Vaccination Schedule ◽  
Optimal Time ◽  
Vaccination Strategies ◽  
Rate Of Spread ◽  
Optimal Window

The SARS-CoV-2 pandemic is a major concern all over the world and, as vaccines became available at the end of 2020, optimal vaccination strategies were subjected to intense investigation. Considering their critical role in reducing disease burden, the increasing demand outpacing production, and that most currently approved vaccines follow a two-dose regimen, the cost-effectiveness of delaying the second dose to increment the coverage of the population receiving the first dose is often debated. Finding the best solution is complex due to the trade-off between vaccinating more people with lower level of protection and guaranteeing higher protection to a fewer number of individuals. Here we present a novel extended age-structured SEIR mathematical model that includes a two-dose vaccination schedule with a between-doses delay modelled through delay differential equations and linear optimization of vaccination rates. Simulations for each time window and for different types of vaccines and production rates were run to find the optimal time window between doses, that is, the one that minimizes the number of deaths. We found that the best strategy depends on an interplay between the vaccine production rate and the relative efficacy of the first dose. In the scenario of low first-dose efficacy, it is always better to apply the second dose as soon as possible, while for high first-dose efficacy, the optimal window depends on the production rate and also on second-dose efficacy provided by each type of vaccine. We also found that the rate of spread of the infection does not affect significantly the thresholds of the optimal window, but is an important factor in the absolute number of total deaths. These conclusions point to the need to carefully take into account both vaccine characteristics and roll-out speed to optimize the outcome of vaccination strategies.

Systemic effect of radiotherapy before or after nivolumab in lung cancer: an observational, retrospective, multicenter study

2021 ◽  
pp. 030089162110047
Author(s):  
Maria Bassanelli ◽  
Biagio Ricciuti ◽  
Diana Giannarelli ◽  
Fabiana Letizia Cecere ◽  
Michela Roberto ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Advanced Nsclc ◽  
Time Window ◽  
Cox Model ◽  
Critical Role ◽  
Progression Free Survival ◽  
Systemic Effect ◽  
Optimal Time ◽  
Rank Statistic ◽  
Kaplan Meier

Background: The combination of radiotherapy (RT) and programmed death 1 inhibitors seems to increase antitumor immune responses. Objective: To assess the outcome and the role of the best combination sequence, i.e. immunotherapy given before, during, and/or after RT, in patients with non-small cell lung cancer (NSCLC). Methods: We conducted an observational, retrospective analysis of 95 consecutive patients with advanced NSCLC who received any radiotherapy treatment and nivolumab, as clinically indicated. Median overall survival (OS) and the 95% confidence interval (CI) were estimated with the Kaplan-Meier method. Cox model was used to obtain hazard ratio (HR) and associated 95% CI with statistical inference by log-rank statistic. Results: Median OS was 11.9 months (95% CI, 6.6–17.2). Patients who received radiotherapy during an immune checkpoint inhibitor treatment started more than 60 days before showed a better outcome than patients who started immunotherapy over 60 days after RT ending (HR, 2.90 [1.37–6.12], p = 0.005; median OS, 22.4 months vs 8.6 months, p = 0.005). Median progression-free survival was 6.3 months (95% CI, 4.6–8.0). Conclusions: This study shows that combining irradiation with nivolumab for the treatment of advanced NSCLC leads to improved OS. The optimal time window for the combination of RT and immunotherapy seems to play a critical role for therapeutic antitumor response derived by abscopal effect.

scholarly journals Practical aspects of estimation of optimal time for vaccination of chicken against IBD with use of „Deventer formula”

2016 ◽  
Vol 19 (2) ◽  
pp. 425-427
Author(s):  
M. Śmiałek ◽  
A. Śmiałek ◽  
A. Koncicki
Keyword(s):  
Vaccination Schedule ◽  
Yolk Sac ◽  
Infectious Bursal Disease ◽  
Optimal Time ◽  
Blood Collection ◽  
Live Vaccines ◽  
Vaccination Strategies ◽  
Bursal Disease ◽  
The Impact

Abstract One of the most commonly applied vaccination strategies against chicken infectious bursal disease (IBD) is the use of live vaccines at the optimal time estimated with the use of Deventer formula. The present study investigated the impact of different factors on maternally derived antibodies decline and therefore on the vaccination schedule against IBD. Our results suggest that blood collection from birds older than 3 days is more reliable in order to estimate the optimal date for IBD vaccination, due to disturbances in yolk sac resorption early after hatch.

scholarly journals Combating pertussis resurgence: One booster vaccination schedule does not fit all

2015 ◽  
Vol 112 (5) ◽  
pp. E472-E477 ◽  
Author(s):  
Maria A. Riolo ◽  
Pejman Rohani
Keyword(s):  
Booster Vaccination ◽  
Cost Effective ◽  
Vaccination Schedule ◽  
Health Concern ◽  
Transmission Model ◽  
Public Health Concern ◽  
Vaccine Failure ◽  
Vaccination Strategies ◽  
Vaccine Booster ◽  
Pertussis Epidemiology

Pertussis has reemerged as a major public health concern in many countries where it was once considered well controlled. Although the mechanisms responsible for continued pertussis circulation and resurgence remain elusive and contentious, many countries have nevertheless recommended booster vaccinations, the timing and number of which vary widely. Here, using a stochastic, age-stratified transmission model, we searched for cost-effective booster vaccination strategies using a genetic algorithm. We did so assuming four hypothesized mechanisms underpinning contemporary pertussis epidemiology: (I) insufficient coverage, (II) frequent primary vaccine failure, (III) waning of vaccine-derived protection, and (IV) vaccine “leakiness.” For scenarios I–IV, successful booster strategies were identified and varied considerably by mechanism. Especially notable is the inability of booster schedules to alleviate resurgence when vaccines are leaky. Critically, our findings argue that the ultimate effectiveness of vaccine booster schedules will likely depend on correctly pinpointing the causes of resurgence, with misdiagnosis of the problem epidemiologically ineffective and economically costly.

scholarly journals Evaluation of COVID-19 vaccination strategies with a delayed second dose

PLoS Biology ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. e3001211
Author(s):  
Seyed M. Moghadas ◽  
Thomas N. Vilches ◽  
Kevin Zhang ◽  
Shokoofeh Nourbakhsh ◽  
Pratha Sah ◽  
...  
Keyword(s):  
Program Effectiveness ◽  
Credible Interval ◽  
The United States ◽  
Optimal Time ◽  
Time Interval ◽  
Policy Debate ◽  
Agent Based ◽  
Vaccination Strategies ◽  
Supply And Distribution ◽  
The Impact

Two of the Coronavirus Disease 2019 (COVID-19) vaccines currently approved in the United States require 2 doses, administered 3 to 4 weeks apart. Constraints in vaccine supply and distribution capacity, together with a deadly wave of COVID-19 from November 2020 to January 2021 and the emergence of highly contagious Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants, sparked a policy debate on whether to vaccinate more individuals with the first dose of available vaccines and delay the second dose or to continue with the recommended 2-dose series as tested in clinical trials. We developed an agent-based model of COVID-19 transmission to compare the impact of these 2 vaccination strategies, while varying the temporal waning of vaccine efficacy following the first dose and the level of preexisting immunity in the population. Our results show that for Moderna vaccines, a delay of at least 9 weeks could maximize vaccination program effectiveness and avert at least an additional 17.3 (95% credible interval [CrI]: 7.8–29.7) infections, 0.69 (95% CrI: 0.52–0.97) hospitalizations, and 0.34 (95% CrI: 0.25–0.44) deaths per 10,000 population compared to the recommended 4-week interval between the 2 doses. Pfizer-BioNTech vaccines also averted an additional 0.60 (95% CrI: 0.37–0.89) hospitalizations and 0.32 (95% CrI: 0.23–0.45) deaths per 10,000 population in a 9-week delayed second dose (DSD) strategy compared to the 3-week recommended schedule between doses. However, there was no clear advantage of delaying the second dose with Pfizer-BioNTech vaccines in reducing infections, unless the efficacy of the first dose did not wane over time. Our findings underscore the importance of quantifying the characteristics and durability of vaccine-induced protection after the first dose in order to determine the optimal time interval between the 2 doses.

Determination of optimal time window for cortical mapping in awake craniotomy: assessment of intraoperative reaction speed

2019 ◽  
Vol 43 (2) ◽  
pp. 633-642
Author(s):  
Dziugas Meskelevicius ◽  
Artur Schäfer ◽  
Jasmin Katharina Weber ◽  
Lisa Hegmann ◽  
Lisa Haddad ◽  
...  
Keyword(s):  
Time Window ◽  
Awake Craniotomy ◽  
Cortical Mapping ◽  
Optimal Time ◽  
Reaction Speed

scholarly journals An Optimization Model for Advanced Life Support Ambulance Facility Location Problem

Proceedings ◽  
2020 ◽  
Vol 39 (1) ◽  
pp. 10 ◽  
Author(s):  
Sumrit ◽  
Thongsiriruengchai
Keyword(s):  
Facility Location ◽  
Service Time ◽  
Traffic Congestion ◽  
Location Problem ◽  
Life Support ◽  
Time Window ◽  
Critical Role ◽  
Advanced Life Support ◽  
Facility Location Problem ◽  
Service Areas

The survival rate of the patients in medical emergencies depends on the minimize ambulance arrival time on-sites and promptly provides medical care to the patients. Advanced Life Support (ALS) ambulances play a critical role in reducing the fatal and severity rate of emergency patients. The several areas in big cities always encounter with traffic congestion, which is a significant obstacle for ALS ambulances to achieve their service time window target (predetermine as less than 8 min). In light of prior research, arranging appropriate parking locations can solve such a problem. This study proposes a mathematical model of facility location problem to identify the ALS ambulances parking locations. This paper simultaneously considers the minimize of the total number of ALS ambulance parking locations while covering the service areas and service time window are fulfilled. One part of business centers in Bangkok was chosen to correct the data and test the proposed model. This study is distinguished from others in these areas by the only possible parking places, i.e., schools, temples, police stations, and gas stations, which are taking into consideration. IBM ILOG CPLEX Optimization Studio Version 12.6.1 was utilized to solve the problem. The result indicates that there are 26 parking locations, which can enable the service coverage areas. As well as achieve a 54% service time window target.

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