Pregnant women who have
gotten their booster vaccine against whooping cough (pertussis) have reason to
cheer: their newborns are far less likely to get the disease than any other
babies. One of the largest ever studies looking at the effectiveness of
prenatal vaccination against pertussis found the vaccine is more than 91%
effective in preventing the life-threatening infection in the first two months
of life. That’s greater than the average 85% protection provided by the vaccine
after the second shot recommended for babies at 4 months by the Centers for
Disease Control and Prevention.
“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, M.D., Ph.D., co-director of the Kaiser Permanente Vaccine Study Center
and a clinical instructor at Stanford University School of Medicine.
The Tdap is the adult
version of the DTaP: both vaccines protect against tetanus, diphtheria and
pertussis but have slightly different formulations. The high level of maternal
antibodies’ effectiveness is likely due to the stronger response of the
mother’s more mature immune system. Infants’ immune systems develop antibodies
in response to the CDC-recommended DTaP vaccine series, but they remain less
mature than an adult’s system.
Since 2013, the CDC has
recommended that pregnant women receive a booster shot of the Tdap vaccine in
every pregnancy, preferably between 27 and 36 weeks. The vaccine, which
protects against pertussis, tetanus and diphtheria, is recommended no matter
when a woman’s last booster was—even if it was a year earlier in a previous
pregnancy. The reason? Increasing infection rates.
Unlike other
vaccine-preventable diseases in the United States, rates of pertussis, or
whooping cough, have been increasing in the past decade or so. Several reasons
explain the increase, but the biggest contributor is the decreasing immunity
provided by the vaccine over time. The immunity a person develops from the
vaccine wanes more quickly than the immunity provided by a previous vaccine,
abandoned in the 1990s due to more frightening (though not more harmful)
vaccine reactions.
Author: Tara
Haelle
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