Varicella zoster virus countries. Varicella vaccination has raised concerns in some that the immunity induced by the vaccine may not be lifelong, possibly leaving adults vulnerable to more severe disease as the immunity from their childhood immunization wanes. Vaccine coverage in the United States in the population recommended for vaccination is approaching 90%, with concomitant reductions in the incidence of varicella cases and hospitalizations and deaths due to VZV. So far, clinical data has proved that the vaccine is effective for over 10 years in preventing varicella infection in healthy individuals and when breakthrough infections do occur, illness is typically mild. In 2007,
Centers for Disease Control and Prevention including those indicated below. The Epidemic Intelligence Service (EIS) is composed of "boots-on-the-ground disease detectives" who investigate public health problems domestically and globally. When called upon by a governmental body, EIS officers may embark on short-term epidemiological assistance assignments, or "Epi-Aids", to provide technical expertise in containing and investigating disease outbreaks. The EIS program is a model for the international Field Epidemiology Training Program. The CDC also operates the Public Health Associate Program (PHAP), a two-year paid fellowship for recent college graduates to work in public health agencies all over the United States. PHAP was founded in 2007 and currently