Zhen Zhao

Risk Factors Associated with Children Missing the Fourth Dose of DTaP Vaccination

Zhen Zhao · Journal of Advances in Medicine and Medical Research · 2015

Background: In 2012, reported pertussis reached the highest number of cases (48,277) in the United States since 1955. Objectives: Estimate the prevalence of children who missed the fourth dose of DTaP (Diphtheria and Tetanus toxoids and acellular Pertussis vaccine) by parents’ co...

Open access Research Article 10.9734/BJMMR/2015/16117

Calculating Adjusted Survival Functions for Complex Sample Survey Data and Application to Vaccination Coverage Studies with National Immunization Survey

Zhen Zhao, Philip J. Smith, David Yankey & Kennon R. Copeland · Journal of Advances in Mathematics and Computer Science · 2014

Background: In vaccination studies with complex sample survey, survival functions have been used since 2002. Recent publications have proposed several methods for evaluating the adjusted survival functions in non-population-based studies. However, alternative methods for calculat...

Open access Research Article 10.9734/BJMCS/2014/10183