News: Pertussis Booster During Pregnancy Helps Protect Babies Too Young for Vaccination

Pertussis, or whooping cough, is a highly contagious disease that can be life-threatening for young children. New research backs a recommendation that all pregnant women receive a pertussis booster with each pregnancy, as it can help their infants fight off the infection.

Caused by a bacterium called Bordetella pertussis, whooping cough remains a significant health problem around the world. In the US, case counts are rising. According to the Centers for Disease Control and Prevention (CDC), there was a 15% increase in reports of whooping cough from 2013 to 2014. While the increase mainly impacted teens aged 13 to 15, young children are the hardest hit by pertussis.

For newborns and infants too young for vaccination, pertussis can quickly become life-threatening. In the first two months of life, infants rely on maternal antibodies to protect them. With age, those antibodies weaken, leaving babies vulnerable.

US doctors report between 20,000 to 40,000 cases of pertussis each year. Among infants, about 50% of those who contract the infection end up in the hospital, and each year about 20 children die. While the mortality rate from pertussis has dropped dramatically since the introduction of vaccines, even one death is tragic.

Because pertussis is highly infectious, as well as virulent, even healthy babies can quickly contract the infection through a cough, sneeze, or close contact with others. Early symptoms of pertussis include a low fever, occasional cough, and runny nose. Frighteningly, some babies experience apnea, a pause in their breathing.

As the disease progresses, the symptoms worsen and may look like this:

• Persistent coughing fits that sound like a "whoop." Vomiting may accompany intense coughing.
• Extreme fatigue can occur after bouts of coughing.

A pertussis infection lingers for up to 10 weeks. As noted by the CDC, in China, pertussis is called the "100-day cough." In the later stages of the infection, the coughing occurs mainly at night. As victims recover, the cough slowly subsides but may return with a later respiratory illness. For infants, the danger is not just the coughing, but a life-threatening tendency to stop breathing, resulting in a bluish hue.

Although vaccines have been available for 70 years, the disease seems to be re-emerging, even among well-vaccinated populations. While there is no agreed-upon explanation for what could be a resurgence, some experts suggest:

• The Bordetella bacterium responsible for pertussis could be adapting, making the vaccine less effective.
• Immunity conferred by current vaccinations may be shorter than expected. Although infants receive several boosters containing diphtheria, tetanus, and acellular pertussis (the DTap booster) from two months of life onward, experts suggest immunity may not be lifelong.
• Patients diagnosed with pertussis may not have pertussis, but a different illness altogether, or a different strain of the bacteria other than B. pertussis.

To see if vaccination of pregnant women could help their babies fight off this infection, researchers at the Kaiser Permanente Vaccine Study Center looked at data from 148,981 babies born between 2006 and 2015 who suffered pertussis. The results, published in the journal Pediatrics, support the recommendation that all pregnant women receive a Tdap booster late in each pregnancy to provide potentially life-saving antibodies to their babies before they can receive the DTap vaccine themselves.

Findings include:

• In the initial years of the study, only about 1% of moms received the Tdap during pregnancy. That number increased to 15% by 2015.
• Infants of women who received the Tdap during pregnancy saw a 91% decrease in risk of contracting pertussis during their first two months of life.
• During their first year of life, infants of vaccinated moms had a 68% decrease in risk of pertussis infection, even when infant vaccination with DTap was factored in.

To reduce the risk of pertussis during the vulnerable first months and year of infancy, the CDC recommends steps families can take to protect young children:

• All pregnant women, during each pregnancy, should receive a Tdap booster between 27 and 36 weeks of pregnancy.
• At least two weeks before the arrival of a new family member, siblings and adults without current vaccinations should receive a booster.
• At two months and going forward, ensure infants receive DTap immunizations on schedule.

Senior author Dr. Nicola P. Klein noted in a press release:

Maternal Tdap administered during pregnancy was highly effective at protecting infants against pertussis prior to their first dose of DTaP. Through the first year of life, maternal Tdap continued to provide protection without interfering with DTaP. It is reassuring that at every level of DTaP exposure, children with maternal Tdap are better protected.

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