Pressroom

Source: MedPage Today

By: Neale, Todd

09/12/2012

A new study suggests that protection from the childhood series of the diphtheria, tetanus, and acellular pertussis (DTaP) vaccine fades within five years of the final dose. The New England Journal of Medicine study involved data on children in Northern California who received a fifth dose of DTaP between the recommended ages of four and six from 2006 to 2011. The study involved 277 children with a positive PCR test for pertussis, 3,318 children with a negative PCR test, and 6,086 matched controls who were not tested for the disease. The children had all received DTaP. The researchers, led by Nicola Klein of the Kaiser Permanente Vaccine Study Center in Oakland, Calif., found that a larger period of time from the fifth dose of vaccine was linked to a higher percentage of positive PCR tests, with 0.8 percent of the tests coming up positive when they were conducted 15 days to one year after the last dose and 18.5 percent showing positive results six to eight years after the fifth dose. “This in an important paper, as it adds to our understanding of the waning immunity with DTaP vaccine,” noted Dr. Mark Sawyer of the University of California San Diego. Sawyer, who is chair of the pertussis vaccines working group for the Advisory Committee on Immunization Practices, said that vaccination is still essential. “Although the current vaccines are less than perfect, they are all we have to protect the population from pertussis,” he said. “Pertussis is very contagious, and we have seen very large outbreaks in many states over the past several years.”