By the time they reach school age most kids have been fully vaccinated against whooping cough, also known as pertussis.
"When we give a dose for pertussis we immunize babies at two months, 4 months, 6 months 15 months and a 5th dose between ages 4 and 6," said KING 5's Doctor Wendy Sue Swanson.
Dr. Wendy Sue Swanson is a pediatrician at Seattle Children's and author of Seattle Mama Doc blog. She said the final pertussis booster, given from age 4 to 6, could pose a problem. A recent study published in the New England Journal of Medicine found the effectiveness of the booster wanes.
"What it looks like is that each and every year after the immunization is given, the protection, in a large group of patients, actually decreases," said Dr. Swanson.
For pediatricians, it may come down to choosing the right time to vaccinate a child she said.
"Do we want to give the shot right at age four? Or will it make more sense to give it right at age six, so that we can buy a little bit more time of protection for children?" she explained the thinking about timing the vaccine.
It's important for parents to make sure your child gets a shot called a T-DaP to boost immunity again around middle school.
"We recommend all children age eleven and up, all adults and even grandparents, particularly those who will ever be around children and newborn babies to have a TDaP vaccine," Dr. Swanson said.
Experts want to reassure parents that kids who get whooping cough after they're vaccinated typically get a milder case with fewer symptoms.
The Washington State Department of Health has more information on the whooping cough epidemic in our state.