In years past, Mom posed the biggest risk
When babies develop whooping cough, it’s most likely a sibling is the source, according to new research. That’s a change; in the past, mothers were most often the culprit.
The change wasn’t completely unexpected, said study author Tami Skoff, an investigator with the Centers for Disease Control and Prevention (CDC).
Cases of whooping cough, or pertussis, have been rising in the United States for the past few years. In 2012, more than 48,000 cases were reported nationwide, the highest number in nearly 60 years, with older children and teens accounting for a growing proportion of cases.
The major reason for this is that in the 1990s, health officials switched from the traditional whooping cough vaccine, which had been linked to rare neurological problems, to a newer, safer one, DTaP. The problem is that DTaP’s disease-prevention effects don’t last as long.
“The vaccine is very effective in the short term,” Skoff said. But the CDC estimates whooping cough immunity wanes each year after a child’s final dose, which is given around age 5.
If a child who has been vaccinated does catch whooping cough, he or she might not get very sick. But they can spread the disease to young infants, who have a high risk of becoming severely ill. According to the CDC, of babies younger than 1 year who get whooping cough, half end up hospitalized.
Newborns’ immune systems can’t handle the DTaP vaccine, so babies are scheduled to receive their first dose at 2 months. That’s followed by doses at 4, 6, and 15 to 18 months, with a final one between the ages of 4 years and 6 years.
The best way to protect infants? Moms should have a whooping cough booster shot—known as Tdap—during the third trimester of pregnancy, Skoff said. Then infants are born with some of mom’s immune system antibodies against the infection, which offers short-term protection.
The study’s findings, published in the journal Pediatrics, are based on more than 1,300 infant whooping cough cases reported to health officials in seven states. When a source of the disease could be identified, it was usually an immediate family member: a sibling in nearly 36 percent of cases, the mother in about 21 percent and the father in 10 percent.
Current CDC recommendations call for all Americans aged 11 and older to have one Tdap booster shot. “Pregnant women are the only group who are advised to have more than one booster,” Skoff said. And because antibodies against whooping cough do not remain at a high level from one pregnancy to another, women need the Tdap booster, which has been shown in studies to be safe for mom and baby, during each pregnancy.