A cost-effectiveness model for analyzing two varicella vaccination strategies.

A model for estimating the cost-effectiveness of a program for vaccinating employees at a health care institution against varicella zoster virus (VZV) was studied. Three outcomes of varicella vaccination--cost-effectiveness, reduction in employee infections, and reduction in patient exposures--were stratified to estimate the incremental costs of vaccinating three employee groups. The groups consisted of all employees (vaccinate-all group), employees providing direct patient care (direct care group), and employees working in high-risk patient care areas (high-risk group). Two strategies for employee vaccination were used: screen (by antibody titer testing) and then vaccinate, and vaccination alone. A model was used to estimate the various outcomes of the vaccination program. The model supported the screen, then vaccinate strategy of vaccinating employees, at a cost savings of about $50 per employee. Vaccination of all employees prevented 35 employee infections and 674 patient exposures for every 10,000 potentially susceptible employees. The cost of preventing one employee infection was about $15,000, and the cost of preventing one patient exposure was about $775. An employee vaccination program is a good investment in preventing patient exposures to VZV and may be cost-effective compared with only screening employees.