Pertussis Vaccine in Pregnancy Protects Nine of 10 Newborns from Whooping Cough

A new study shows newborns of pregnant women who have gotten their pertussis booster vaccine are far less likely to get the disease than other babies. In the study, researchers tracked 148,981 full-term infants born at Kaiser Permanente Northern California between 2010 and 2015. All women were born prior to 1996, when the vaccine containing a whole pertussis bacteria cell was fully replaced by the current vaccine, which contains only a few proteins of the bacteria. Forty-six percent of mothers received the Tdap (tetanus, diphtheria, pertussis) vaccine during pregnancy at least eight days before giving birth. At 2 months old, infants of mothers who got the Tdap during pregnancy were 91.4 percent protected against pertussis. As the mothers’ antibodies gradually declined by the time of each recommended DTaP vaccine for children, the researchers found the mothers’ Tdap booster was still an average 88 percent effective just before the first dose of DTaP and 82 percent effective between the first and second doses. Maternal antibodies remained 69 percent effective against infection through the end of the child’s first year.

The study also found high rates of prenatal vaccination. From 2014 to 2015, national rates of pertussis vaccination in pregnancy ranged from 27 percent to 42 percent. But at Kaiser Permanente Northern California, rates were at 12 percent in 2010 and rose to 87 percent in 2015.

“The bottom line is that receiving Tdap during pregnancy is extremely effective in protecting infants against pertussis across the first year of life,” said senior author Nicola Klein, MD, PhD, co-director of the Kaiser Permanente Vaccine Study Center and a clinical instructor at Stanford University School of Medicine.