It’s difficult to imagine a more contagious disease than whooping cough.
For adolescents and adults, whooping cough, or pertussis, is a huge bother: cold symptoms, followed by a cough that takes weeks or months to resolve. Missed work and school are common. But for infants who haven’t yet been immunized, whooping cough can be serious -- even life threatening.
“Pertussis has caused about 30 deaths a year in the U.S. recently, almost all of them in children younger than three months old,” says Harry Keyserling, MD, professor of pediatric infectious disease at Emory University in Atlanta and a spokesman for the American Academy of Pediatrics. “Children this young usually have severe illness requiring hospitalization and are at high risk for complications like pneumonia and seizures.”
Preventing whooping cough starts by recognizing how young children usually catch the bacteria: from other family members. “In most cases, it’s a parent or sibling that passes pertussis to a child,” says Keyserling.
Bordetella pertussis is a bacterium that can live in the human respiratory tract. The bacteria is easily spread through sneezes and coughs, often from people who often don’t even know they have the infection.
Whooping Cough Vaccine Immunity Is Short Lived
From 80% to 90% of Americans have been immunized against pertussis. But the pertussis vaccine, like natural pertussis infection, does not provide lifelong protection. Immunity to pertussis wanes five to 10 years after the last childhood vaccine, leaving adolescents and adults susceptible to infection. People who have had pertussis lose their immunity, too.
Pertussis infects at least 600,000 people – and perhaps more than a million people each year in the U.S. The exact number is impossible to determine because whooping cough is rarely recognized in previously immunized people.
Thanks to partial immunity from early vaccination, “their symptoms are mild, like a cold with a cough,” says Keyserling. “Most probably never need or seek medical attention.” And, most have no idea their symptoms are actually whooping cough.
Even so, they can and do pass the pertussis bacteria to other people. Older children and adults aren’t at serious risk from infection -- although “mild” whooping cough symptoms still can mean a cough that lasts for more than a month, usually causing lost sleep and missed school or work days.
The real threat, however, comes from spreading pertussis to a very young, incompletely vaccinated child.
Unvaccinated Babies Are Especially Vulnerable to Whooping Cough
The pertussis vaccine, called DTaP (for diphtheria, tetanus, and pertussis), is typically given in five doses. The first four shots are given during a baby’s first year and a half of life: at 2, 4, 6, and 15 to 18 months. A final dose is given between 4 and 6 years of age.