Teenagers who were vaccinated with four doses of acellular vaccines were at almost six times higher risk of pertussis than were those who had received four doses of whole-cell vaccines. Persons who received mixed whole-cell and acellular vaccines had an intermediate level of risk between those who received all whole-cell or all acellular vaccines. Those who received mixed vaccines were at nearly four times higher risk of pertussis than were those who received all whole-cell vaccines.
Earlier studies by Kaiser Permanente have shown that protection from the fifth dose of acellular pertussis vaccine wanes substantially during the five years after vaccination among children 4 to 12 years of age who have only received the acellular vaccine. The current study included only individuals born in 1999 or earlier, for whom at least five years had passed since receipt of the fifth pertussis vaccine.
Since 2005, the Advisory Committee on Immunization Practices has recommended boosting with reduced antigen content acellular pertussis vaccine, also known as Tdap, for persons 11 years and older. The study found that a booster dose of Tdap did not overcome the advantage in protection from pertussis seen among those who had received four doses of the whole-cell vaccine.
"The results indicate that a booster dose of Tdap does not overcome the advantage in protection from pertussis afforded to those who previously received four doses of the whole-cell vaccine," Dr. Klein said. "Despite this, boosting the newly emerging cohort of acellular pertussis vaccine-only teenagers with Tdap remains the best means currently available to help protect this group against disease."
|Contact: Vincent Staupe|