Panel recommends adult pertussis vaccine

Washington -- Most adults who need a tetanus and diphtheria booster should now be given a single dose of a newly approved vaccine for tetanus, diphtheria and acellular pertussis, or Tdap, instead, according to Oct. 26 recommendations from the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices.

The new vaccine, which was approved for use in adults last June, adds protection from pertussis to the traditional tetanus-diphtheria, or Td, booster.

The vaccine should not be administered within two years of the time a Td shot was given, the committee said.

Adults who are in close contact with infants younger than 1 year and women who have just given birth or are of childbearing age are also being urged to receive the Tdap vaccine if two years have passed since their last Td booster. Recommendations for health care workers, pregnant women and adults older than 65 are still being developed.

The new recommendations are intended to reduce the rising incidence of pertussis in the United States.

The CDC received reports of about 26,000 cases of pertussis in 2004, but the actual number is probably closer to 600,000 cases a year, said Katrina Kretsinger, MD, a medical epidemiologist with the CDC.

The disease often goes unreported because many physicians don't recognize it in their adult patients. Difficulties in establishing an exact diagnosis can also cause many cases to be missed, said Susan Rehm, MD, medical director of the National Foundation for Infectious Diseases, which sponsored a Nov. 9 briefing on the ACIP recommendations.

Adults now account for nearly one-third of all pertussis cases, said Dr. Rehm, and those numbers are increasing. Among adults 20 and older, the number of pertussis cases rose 150% from 2003 to 2004.

Immunity provided by the vaccine begins to decline after about five to 10 years, said Dr. Kretsinger. "This means that adolescents and adults can become ill with pertussis."

Although the disease is serious among adults, it is usually not fatal. The greater danger is the possibility that pertussis will transmit to young infants who are not yet fully immunized, to whom it can be much more serious and even fatal.

The new vaccine, Adacel, is manufactured by Sanofi Pasteur.