Among infants of women who received the Tdap pertussis booster vaccine during pregnancy, the risk of contracting pertussis was reduced by an estimated 91 percent during the first two months of life ? the critical period before they can receive their first childhood acellular pertussis (DTaP) vaccination. The findings from the Kaiser Permanente Vaccine Study Center were reported today in the journal Pediatrics.
the study found that maternal Tdap vaccination during pregnancy reduced pertussis risk by an estimated 69 percent for the entire first year of life, after adjustment for the effects of infant DTaP vaccinations administered starting at age two months.
The study is the latest in a seminal and influential body of work on pertussis vaccines by the Vaccine Study Center. KPVSC research was the first to show that the acellular pertussis DTaP vaccine, introduced in the 1990s, did not provide the long-term protection of the whole cell vaccine (DTwP) that it replaced. Furthermore, KPVSC researchers found that the protective effect of DTaP decreases dramatically soon after the last of the five recommended shots are received around ages 4 to 6. The findings explained in large part why the United States was seeing increasing outbreaks of whooping cough. Further research has shown similar waning effectiveness for the Tdap booster.
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“The strategy of immunizing pregnant women to boost maternal antibody transfer appears to be more effective for protecting young infants against pertussis than are attempts at ‘cocooning,’ in which mothers and other persons in close contact with newborns are vaccinated after the birth,” said Nicola P. Klein, MD, PhD, senior author and KPVSC director.