CDC officials say the Tdap vaccine helps save lives. However, many pregnant women aren’t getting the shots.

A vaccine given to pregnant women may prevent the vast majority of whooping cough cases in newborns.

That’s according to a new study from the Centers for Disease Control and Prevention (CDC).

Whooping cough, also known as pertussis, is a bacterial respiratory disease that’s especially dangerous for infants too young to be vaccinated.

The disease, which can lead to violent and uncontrollable coughing, was reported in 15,737 cases in 2016, according to the CDC.

In rare cases, the disease can cause death, especially in infants under 2 months old.

A study published Thursday in Clinical Infectious Diseases concluded that these vulnerable infants could be protected if doctors vaccinated pregnant women late in their pregnancy.

CDC researchers looked at data from six states between 2011 to 2014 that are part of the U.S. Emerging Infection Program Network.

The researchers found that of the 775 pregnant women they studied, those who received a pertussis vaccine as part of a Tdap (tetanus, diphtheria, and pertussis) vaccination late in their pregnancy were less likely to have newborn children who contracted whooping cough.

In total, they found getting the Tdap vaccine during the third trimester of pregnancy prevented 78 percent of whooping cough cases in newborns under the age of 2 months.

Dr. Amy Edwards, a pediatric infectious disease specialist at UH Rainbow Babies & Children’s Hospital in Ohio, said the findings weren’t surprising, but were still helpful.

“It’s kind of what we have thought all along,” she told Healthline “It’s just nice to get a good study that’s starting to show what we already suspected.”

Edwards said doctors already suggested pregnant women get the Tdap vaccine late in their pregnancy because they knew there was a “huge transfer across the placenta of mom’s immune system to the baby.”

“If there’s a nice big, huge pertussis antibody response going on,” she explained, “then presumably a good chunk of antibodies are transferred over to [the] baby.”

The CDC researchers also found that despite the benefits for the infant, only 49 percent of pregnant women received this vaccine during their pregnancy in 2015 and 2016.

“Women have such a great opportunity to help protect their babies before they enter the world by getting Tdap vaccine while pregnant,” Dr. Nancy Messonnier, director of CDC’s National Center for Immunization and Respiratory Diseases, said in a statement. “This study highlights how babies can benefit when their mothers get the vaccine and reinforces [the] CDC’s recommendation for women to get [the] Tdap vaccine in the third trimester of each pregnancy.”

The whooping cough vaccine is approximately 80 to 90 percent effective, but protection wanes over time.

Edwards said pregnant women are recommended to get a Tdap booster during every pregnancy to help protect the infant.

In severe cases, whooping cough can lead to pulmonary hypertension or high blood pressure in the blood vessels of the lungs.

For infants, this can lead to heart failure and death.

“That’s the risk with the little babies… that we just dread,” Edwards said. “There’s very little we can do for that.”