Varicella vaccine from a child with natural varicella, introduced into human embryonic lung cell cultures, adapted to and propagated in embryonic guinea pig cell cultures, and finally propagated in human diploid cell cultures. Japan was among the first countries to vaccinate for chickenpox. The vaccine was first licensed in the United States in 1995. Routine vaccination against varicella zoster virus is also performed in the United States, and the incidence of chickenpox has been dramatically reduced there (from 4 million cases per year in the pre-vaccine era to approximately 400,000 cases per year as of 2005). In Europe most countries do not
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