Protection against pertussis decreases during the five years after the fifth dose of the combined diphtheria, tetanus, acellular pertussis vaccine, according to a study.
The study period included a large pertussis outbreak that occurred in California in 2010. Researchers with the Kaiser Permanente Vaccine Study Center examined the relationship between time since vaccination and the likelihood of a positive pertussis test in the Kaiser Permanente Northern California population, which includes 3.3 million members in an integrated care system with electronic medical records and a central laboratory.
The researchers compared 277 children, ages 4 to 12, who tested positive for pertussis with 3,318 children who tested negative for pertussis and separately with 6,086 matched controls. They assessed the risk of pertussis in children from 2006 to 2011 in California relative to the time since the fifth dose of DTaP and found that after the fifth dose of DTaP, the odds of acquiring pertussis increased by an average of 42% per year
The amount of protection remaining after five years depended heavily on the initial effectiveness of the fifth dose of DTaP, said Nicola Klein, MD, PhD, the study’s lead author and co-director of the Kaiser Permanente Vaccine Study Center.
If the initial effectiveness rate of the fifth dose of DTaP were 95%, it would decrease to 71% after five years. But if the initial effectiveness were 90%, it would decline to 42% after five years.
"The findings suggest that whooping cough control measures may need to be reconsidered," Klein said in a news release. "Prevention of future outbreaks may be best achieved by developing new pertussis-containing vaccines or reformulating current vaccines to provide long-lasting immunity."
"That said, the DTaP vaccine is effective and remains an important tool for protection against whooping cough for children and the communities in which they live, and following current CDC recommendations remains important."
The Centers for Disease Control and Prevention recommends five DTaP shots for children. The first three are given at ages 2, 4 and 6 months. The fourth shot is given between ages 15 and 18 months, and a fifth shot is given when a child enters school, between ages 4 and 6 years.
The first pertussis vaccine was developed in the 1930s and was in widespread use by the mid-1940s, when pertussis vaccine was combined with diphtheria and tetanus toxoids to make the combination whole-cell pertussis vaccine DTP. In 1991, concerns about DTP safety led to the development of the acellular pertussis DTaP vaccines, which are associated with fewer side effects. DTaP vaccines have completely replaced the whole-cell DTP vaccines in the United States and many other countries.
The study appears in the Sept. 13 issue of the New England Journal of Medicine. The study abstract is available at www.nejm.org/doi/full/10.1056/NEJMoa1200850?query=featured_home.
The study period included a large pertussis outbreak that occurred in California in 2010. Researchers with the Kaiser Permanente Vaccine Study Center examined the relationship between time since vaccination and the likelihood of a positive pertussis test in the Kaiser Permanente Northern California population, which includes 3.3 million members in an integrated care system with electronic medical records and a central laboratory.
The researchers compared 277 children, ages 4 to 12, who tested positive for pertussis with 3,318 children who tested negative for pertussis and separately with 6,086 matched controls. They assessed the risk of pertussis in children from 2006 to 2011 in California relative to the time since the fifth dose of DTaP and found that after the fifth dose of DTaP, the odds of acquiring pertussis increased by an average of 42% per year
The amount of protection remaining after five years depended heavily on the initial effectiveness of the fifth dose of DTaP, said Nicola Klein, MD, PhD, the study’s lead author and co-director of the Kaiser Permanente Vaccine Study Center.
If the initial effectiveness rate of the fifth dose of DTaP were 95%, it would decrease to 71% after five years. But if the initial effectiveness were 90%, it would decline to 42% after five years.
"The findings suggest that whooping cough control measures may need to be reconsidered," Klein said in a news release. "Prevention of future outbreaks may be best achieved by developing new pertussis-containing vaccines or reformulating current vaccines to provide long-lasting immunity."
"That said, the DTaP vaccine is effective and remains an important tool for protection against whooping cough for children and the communities in which they live, and following current CDC recommendations remains important."
The Centers for Disease Control and Prevention recommends five DTaP shots for children. The first three are given at ages 2, 4 and 6 months. The fourth shot is given between ages 15 and 18 months, and a fifth shot is given when a child enters school, between ages 4 and 6 years.
The first pertussis vaccine was developed in the 1930s and was in widespread use by the mid-1940s, when pertussis vaccine was combined with diphtheria and tetanus toxoids to make the combination whole-cell pertussis vaccine DTP. In 1991, concerns about DTP safety led to the development of the acellular pertussis DTaP vaccines, which are associated with fewer side effects. DTaP vaccines have completely replaced the whole-cell DTP vaccines in the United States and many other countries.
The study appears in the Sept. 13 issue of the New England Journal of Medicine. The study abstract is available at www.nejm.org/doi/full/10.1056/NEJMoa1200850?query=featured_home.
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