The Centers for Disease Control and Prevention (CDC) updated their previous recommendations (circa 2002) for using the yellow fever vaccine in their Morbidity and Mortality Weekly Report (available online at CDC.gov). Briefly, yellow fever is transmitted to humans through the bite of an infected mosquito. The yellow fever disease is a vector-borne disease and is endemic to tropical South America and sub-Saharan Africa. Yellow fever, transmitted by mosquitoes, is estimated to affect 200,000 people and kill 30,000 people annually. When people are infected with yellow fever, they may suffer hemorrhagic fever, which can be fatal in about 20 to 50 percent of the people who contract this disease.
There is no cure for this disease; however, a person can reduce their risk of contracting the disease by getting immunized (additional precautions include selective travel locations, selective seasons for travel, occupation/recreation activities engaged, and the local rate of virus transmission during the expected time of travel). The vaccine for yellow fever was originally developed in the 1930s, and at the time, there were two vaccines: the French neurotropic vaccine, and the 17D vaccine.
The French vaccine was manufactured for about 50 or so years, although it was stopped in 1982 because there were increasing reports of patients experiencing neurologically adverse events after being administered the vaccine. The 17D vaccine is still being produced, although there are two sub-strains: 17DD and 17D-204. The 17DD vaccine is manufactured in Brazil, while the 17D-204 vaccine is manufactured in the U.S. and elsewhere. Studies investigating the efficacy of these two strains suggest they are comparable.
Current reports indicate that, since 1970, there have only been about ten cases of ???imported??? yellow fever (seven cases involved Europeans, while three cases involved Americans). The low level of incidence of yellow fever is, in part, attributed to the use of the vaccine. In fact, many countries require people to be vaccinated in order to enter the respective country. For more information, please consult the article on the CDC???s webpage.