In 2012, as whooping cough continued its deadly comeback, the U.S. Centers for Disease Control and Prevention recommended that women get vaccinated against the bacterial infection during each pregnancy.
A new CDC study finds that the preventive measure works. The vaccine, called Tdap (tetanus, diphtheria, and pertussis), cut the risk of whooping cough, or pertussis, by 78 percent in babies younger than two months whose mothers got inoculated in their third trimester of pregnancy.
The study, published Thursday in Clinical Infectious Diseases, used data from 2011 through 2014 on babies younger than two months from six states. Among babies who developed whooping cough despite their mothers' vaccination, 90 percent had mild cases and did not require hospitalization.
While the latest findings are heartening, only about half of pregnant women in the U.S. are getting the vaccine, the CDC said.
Babies cannot be vaccinated against whooping cough until they're 2 months old. The respiratory illness induces such uncontrollable fits of coughing that it can be deadly for babies, who can stop breathing, have seizures, develop pneumonia, or suffer brain damage.
Pediatrician Paul A. Offit, a vaccine expert at Children's Hospital of Philadelphia, said: "Babies under 2 months old are only going to be protected by their mother, who passes antibodies on to the child. So we have to do a better job of educating women. I think obstetricians can do a better job, too."
"Women have such a great opportunity to help protect their babies before they enter the world by getting Tdap," Nancy Messonnier, director of the CDC's center for immunization and respiratory diseases, said in a news release. "This study reinforces CDC's recommendation."
Before the introduction of whooping cough vaccine in the 1940s, more than 200,000 cases a year were reported in the U.S. By 1965, that number plummeted to fewer than 10,000 a year. But the disease made a comeback in the 1990s, as the newer "acellular" vaccine — containing only cellular material but not whole cells — was phased in. While it is safer and has fewer side effects than the old version, studies have found that its protective effects wane more quickly than originally expected.