(CNN) -- More adolescents being vaccinated for pertussis appears to result in fewer pertussis-related hospitalizations in infants, according to a new study published in the journal Pediatrics.
"The number of hospitalizations in 2011 we observed were 30% of what we would have expected had there not been a vaccine," says lead study author Dr. Katherine Auger, who also specializes in pediatric hospital patient care at Cincinnati Children's Hospital. "For every 10,000 infants, we saw 3.3 pertussis hospitalizations. We expected 10.7 hospitalizations had there not been a vaccine."
The study looked at hospitalization rates, using nationwide inpatient samples, and compared it to data before and after the so-called Tdap vaccination was recommended for universal administration to adolescents in 2006.
Also known as whooping cough, pertussis is a highly contagious and often serious disease, especially in young children.
Whooping cough is preventable through vaccination, but newborns, who are the most vulnerable to the most serious side effects, can't get the first dose of vaccine until they are 2 months old. Then they need four more vaccinations before they turn 7 to get full protection. This is why young children are highly dependent on the people close to them to be vaccinated.
Last year, nearly 50,000 pertussis cases were reported to the CDC, including 18 deaths. Fortunately, "overall reporting of pertussis has declined during 2013,"according to the CDC website.
Some studies show that half of the infants who contract pertussis got it from an older sibling, Auger said.
In 2005, a booster shot called Tdap was introduced for adolescents and adults. The booster shot builds up immunity against tetanus, diphtheria and pertussis and is recommended for 11- and 12-year-olds at regular check-ups. Adults can replace a dose of their regular tetanus-and-diphtheria shot, given every 10 years, with Tdap, but don't have to wait a decade, according to the CDC.
The vaccine "helps adolescents, but in turn, it indirectly protects babies even more," said Atlanta pediatrician Dr. Jennifer Shu. "Eleven-year-olds have to get a tetanus booster anyway, so (they) might as well get the one that has the whooping cough component in it." She adds, it's a "win-win situation and I don't see any major downsides."
The CDC also recommends that 13-18 year olds who haven't gotten the Tdap shot yet should talk with their parents and their doctor about getting it now.
Babies are the most vulnerable population for life-threatening pertussis. Dr. William Schaffner, head of the preventive medicine department at Vanderbilt University's medical school, says it was thought that by providing a cocoon-like environment for infants by vaccinating people who have contact with them would reduce their risk of getting whooping cough. "Now we have data that it works," he adds, "we have created another reinforcing reason to bring teens in for vaccination, not only against whooping cough but for other diseases as well."
Other ways to protect infants from pertussis include vaccinations for pregnant women. In 2012, a federal advisory committee recommended all pregnant women be immunized for pertussis or whooping cough. The committee says the vaccine should be administered during each pregnancy in the late second or third trimester (27 to 36 weeks gestation), regardless of whether the patient has had Tdap in the past. If that's not possible, the mother should receive the vaccine immediately after childbirth or before leaving the hospital or birthing center, the committee said.
The theory is that pregnant women can pass some of the protection from the vaccine across into the placenta onto the baby, Schaffner said, giving the infant some protection before it can be vaccinated.
Whooping cough may resemble a cold or flu in its symptoms. It begins with a cough and runny nose for one or two weeks. Rapid coughing fits, sometimes ending in a whooping sound, then last for weeks or months.
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