ATLANTA -- Two traveler's vaccines have been discontinued: the only licensed typhoid fever vaccine for children aged 6 months-2 years and the only licensed cholera vaccine in the United States.
Both vaccines were made by Wyeth-Lederle, Dr. Eric Mintz said at the winter meeting of the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices.
The loss of this typhoid vaccine will leave unprotected infants and children under age 2 who travel to typhoid-endemic areas, said Dr. Mintz, a medical epidemiologist at CDC's National Center for Infectious Diseases, Atlanta.
The typhoid vaccine being discontinued was one of three on the U.S. market, but the only one licensed for children as young as 6 months of age. It was 51%-77% effective in preventing typhoid fever over a 2-3 year period--about the same as the other two typhoid vaccines in older populations.
Data from the manufacturer suggest that as many as 3 million people were immunized with the vaccine between 1994 and 1999, but it is not known how many of those were aged 6 months-2 years.
However, it is known that this age group comprises a significant proportion of typhoid fever cases diagnosed in the United States. Between 1994 and 1999, 33 of 491 (6.7%) culture-confirmed cases of typhoid fever in travelers were children aged 6 months-2 years, who could only have received the now-with drawn vaccine.
Alternative vaccines that may prove immunogenic in children under 2 years of age are currently under development. Until they become available, physicians must emphasize that parents pay careful attention to food and beverages consumed by children under 2 years of age who travel to typhoid-endemic areas, Dr. Mintz advised.
Immunization against typhoid fever is recommended for "travelers to areas where there is a recognized risk of exposure to Salmonella typhi (countries in Latin America, Asia, and Africa), who have prolonged exposure to potentially contaminated food or drink, persons with intimate exposure (such as household contact) to a documented S. typhi carrier, and laboratory personnel who work with S. typhi."
Withdrawal of the cholera vaccine may not have a huge impact. The vaccine was only about 50% effective in reducing the incidence of clinical illness for 3-6 months. The CDC had recommended it only to "satisfy entry requirements for persons who anticipate travel to countries [that require it]" and for "special high-risk groups that work and live in highly endemic areas under less than sanitary conditions." No country has officially required evidence of cholera vaccination for entry in several years.
"We have no evidence that the withdrawal of this [cholera] vaccine from the U.S. market has caused or will cause any significant public health problems," Dr. Mintz said.
COPYRIGHT 2001 International Medical News Group
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