Ask the Expert: When Should I Get the TDAP Vaccine?

Pertussis, or whooping cough, can be serious, even fatal, for infants. The best way to protect your newborn from whooping cough is to make sure your friends and family get the TDAP vaccine. We spoke to Margaret Stillman, M.D., about the TDAP, when you should get it, and how long pertussis is contagious.

At what age is whooping cough most dangerous?

When the infant is 6 months and younger, she is most at risk for severe disease—the younger the infant, the more severe the disease. We start immunizing infants for whooping cough or pertussis at 2 months of age. When she gets that first injection, she will have some immunity within a couple of weeks and with each shot she gets, more immunity. That’s why we try and cocoon the infant by vaccinating day care workers, parents, grandparents, anyone that surrounds the infant.

If an adult is not sure if she has received a whooping cough vaccine booster, is it advisable to receive one if they are going to be around newborns? Is there any risk if that adult was vaccinated within the last 10 years but then gets the booster again within that time frame?

It is recommended to get the TDAP—tetanus, diphtheria, acellular pertussis—only once, but, to my knowledge, there’s no risk to getting it more than once. If you don’t know whether you’ve had it before and you’re going to be around children, you have to get it. But the current recommendation is that you get it just once and then after that you get the tetanus and diphtheria booster every 10 years.

Is it safe for women to get the TDAP when they are pregnant or is it advisable to get it before or after pregnancy?

It is actually recommended that if a pregnant woman has not had the TDAP that she get it during pregnancy but the latter half of pregnancy, so in the late second trimester or in the third trimester. If she delivers her baby and has not had the TDAP, it is recommended that she get it at that time. (Currently, the Center for Disease Control recommends pregnant women to get the TDAP during each pregnancy to give their infant some short-term protection from whooping cough early in life.)

If my infant received the pertussis vaccine series, do they have to get the TDAP later in life?

In 1997, we switched vaccines from what was called the whole-cell to acellular. It has many fewer side effects but not as good protection. When you get whooping cough you don’t ever develop permanent immunity to it—same with the vaccine. The immunity from these new vaccines has been dropping so there have been whooping cough outbreaks. With each vaccination, we're boosting the infant’s immunity to whooping cough. During childhood they get the five shot vaccination series—at 2 months, 4 months, 6 months, 15-18 months, and 4-6 years. Then, when they’re 11 and before 6th grade, the child gets the TDAP booster to boost the immunity.

What are some of the warning signs that I might be carrying the pertussis bacteria? If I do suspect I have whooping cough, how long should I wait before visiting an infant?

In adults, pertussis presents as a prolonged cough. If you know that whooping cough is going around and you have a prolonged cough—whooping cough will last 6-10 weeks—you should go to your physician for an evaluation. Often by the time it is diagnosed as pertussis, you’ve already had it for a while, so you’ve been contagious without knowing you had it.

It’s most contagious early on in the illness, particularly in the first two weeks, when you have the nonspecific symptoms, such as runny nose, and early on in the cough, so you’re often contagious before you really know it. What commonly happens if you are diagnosed with pertussis is you are put on antibiotics. After you’re on antibiotics for five days, you’re no longer contagious. If 21 days have passed before you’re diagnosed, you’re also viewed as essentially not contagious.

Margaret Stillman, M.D., practices general pediatrics at Pediatrics of Sleepy Hollow in Tarrytown, NY and is the department head for pediatrics at Phelps Memorial Hospital Center in Sleepy Hollow, NY.