[Evaluation of the effect of varicella outbreak control measures through a discrete time delay SEIR model].

Objective: forecast the epidemic trend and to evaluate the effect of outbreak control measures by investigation of a varicella outbreak event with a discrete time delay SEIR model.

Methods: A discrete time delay model was formulated by discretization method based on a continuous SEIR model with the consideration of the time delay effect on latent period and communicable period. The epidemic trend forecast was carried out based on the number of expected cases.

[Comparison of mail and meeting forms in evaluation of Delphi study].

Objective: To evaluate and compare mail and meeting forms in evaluation of Delphi study.

Methods: Delphi study by mail and meeting approaches was used to determine the health information dataset. Experts were required to grade the listed items through three indexes: importance, necessity and availability.

[Design of field studies on vaccines which involves capturing indirect effect].

For most variety of vaccines, two types of effects-direct and indirect, can result from immunization programs. Unimmunized individuals in the population that receive immunization program can benefit from the vaccines in addition to the protection from immunization. The classical vaccine trails allocate individuals into study and control arms with individual randomization, so the programs' cost-benefit is underestimated due to the impossible measurement on indirect effect.