[Cost-effectiveness of universal childhood vaccination against hepatitis A in Spain: a dynamic approach]. / Coste-efectividad de la vacunación universal infantil frente a la hepatitis A en España: un enfoque dinámico.

OBJECTIVE: To evaluate the cost-effectiveness of infant universal vaccination against hepatitis A in Spain. METHOD: Using a dynamic model and decision tree model, a cost-effectiveness analysis was performed to compare three vaccination strategies against hepatitis A: non-vaccination strategy versus universal childhood vaccination of hepatitis A with one or two doses. The perspective of the study was that of the National Health System (NHS) and a lifetime horizon was considered. Both costs and effects were discounted at 3% per year. Health outcomes were measured in terms of quality adjusted life years (QALY) and the cost-effectiveness measure used was the incremental cost-effectiveness ratio (ICER). In addition, deterministic sensitivity analysis by scenarios was performed. RESULTS: In the particular case of Spain, with low endemicity for hepatitis A, the difference in health outcomes between vaccination strategies (with 1 or 2 doses) and non-vaccination are practically non-existent, terms of QALY. In addition, the ICER obtained is high, exceeding the limits of willingness to pay from Spain (€22,000-25,000/QALY). The deterministic sensitivity analysis showed that the results are sensitive to the variations of the key parameters, although in no case the vaccination strategies are cost-effective. CONCLUSIONS: Universal infant vaccination strategy against hepatitis A would not be a cost-effective option from the NHS perspective in Spain.

Modified SIQR model for the COVID-19 outbreak in several countries.

In this paper, we propose a modified Susceptible-Infected-Quarantine-Recovered (mSIQR) model, for the COVID-19 pandemic. We start by proving the well-posedness of the model and then compute its reproduction number and the corresponding sensitivity indices. We discuss the values of these indices for epidemiological relevant parameters, namely, the contact rate, the proportion of unknown infectious, and the recovering rate. The mSIQR model is simulated, and the outputs are fit to COVID-19 pandemic data from several countries, including France, US, UK, and Portugal. We discuss the epidemiological relevance of the results and provide insights on future patterns, subjected to health policies.

Viscoelastic Effects on the Response of Electroelastic Materials.

Electroelastic materials, as for example, 3M VHB 4910, are attracting attention as actuators or generators in some developments and applications. This is due to their capacity of being deformed when submitted to an electric field. Some models of their actuation are available, but recently, viscoelastic models have been proposed to give an account of the dissipative behaviour of these materials. Their response to an external mechanical or electrical force field implies a relaxation process towards a new state of thermodynamic equilibrium, which can be described by a relaxation time. However, it is well known that viscoelastic and dielectric materials, as for example, polymers, exhibit a distribution of relaxation times instead of a single relaxation time. In the present approach, a continuous distribution of relaxation times is proposed via the introduction of fractional derivatives of the stress and strain, which gives a better account of the material behaviour. The application of fractional derivatives is described and a comparison with former results is made. Then, a double generalisation is carried out: the first one is referred to the viscoelastic or dielectric models and is addressed to obtain a nonsymmetric spectrum of relaxation times, and the second one is the adoption of the more realistic Mooney-Rivlin equation for the stress-strain relationship of the elastomeric material. A modified Mooney-Rivlin model for the free energy density of a hyperelastic material, VHB 4910 has been used based on experimental results of previous authors. This last proposal ensures the appearance of the bifurcation phenomena which is analysed for equibiaxial dead loads; time-dependent bifurcation phenomena are predicted by the extended Mooney-Rivlin equations.