State’s rising whooping cough rate demonstrate vital need for vaccination | Guest op

Published 10:50 am Monday, June 1, 2015

By Wendy Sue Swanson, MD, MBE, FAAP
Seattle Children’s Hospital

This year, Washington state is seeing a large number of whooping cough cases, and most of them in teenagers 18 years or younger.

Since the start of the year, 567 cases of pertussis have been reported as of mid- May. That’s compared to 118 cases reported during the same time-period in 2014.

With the increase of whooping cough cases in our state, two new Pediatrics studies have just been released that teach us more about the effectiveness of the whooping cough vaccine. There’s a lot to learn about how we protect babies, and there are reminders here why we’re immunizing moms during every pregnancy.

First, the good news. We have been trained to tell parents that the first shots we give during infancy aren’t fully protective for infants but, rather, the beginning of creating immunity against the diseases they prevent. A study conducted by researchers at the CDC, however, looked back at cases of infants with pertussis from 1991-2008. It found evidence that babies who received their whooping cough shot as early as they could (the age of 6 weeks), were less likely to be hospitalized and/or die from the infection.

Immunize early

New parents can increase protection, even during outbreaks like our current one, by getting their babies immunized on-time and as early as possible.

The not-so-good news is that the effectiveness of the Tdap shot given to young teens wanes significantly in the years after the 11-year-old booster is given. New research reveals after one year, about 70 percent of teens are still protected from the booster, but by four years after the shot, only about a one-third of them are.

The predominance of children with the infection may be in part to a change in the Tdap vaccine back in the ’90s when we switched from a vaccine that was “whole cell” to an “acellular” vaccine. The reason for the switch was side effects, and the new shot fortunately doesn’t provoke as many fevers or subsequent seizures in young babies.

Teens growing up now, however, have never had a dose of the “whole cell” shot. Without a dose of the old vaccine, their protection against whooping cough fades after immunization. Protection is not lost, it’s just isn’t as robust.

In the newly released study, which evaluated effectiveness during our state’s 2012 epidemic, researchers and epidemiologists found the vaccine is 73 percent effective one year following the 11-year-old booster, and only about 35 percent effective two to four years after the booster is given.

The realization of the whooping cough vaccine’s fading effectiveness in teens doesn’t change the fact that vaccination is still the best line of defense against whooping cough. In every pregnancy, moms should be given the Tdap during their third trimester. We want their own immune system boosted, and we want to protect newborn babies given they’re the ones at biggest risk. Moms should get the Tdap shot at least two weeks before delivery with every pregnancy.

Do not wait

Further, there is no reason to wait on the first set of shots – typically called the “two-month immunizations.” They can all be given as early as six weeks. If you’re living in an area where there are whooping cough outbreaks, be sure to get your newborn into their provider’s office at six weeks.

Infants, toddlers and children get the DTaP vaccine also at four, six and 15 months of age. Children get a DTaP booster before kindergarten at age four, and children get it at age 10 or 11 years.

Adults and even grandparents who will be around a new baby also need protection. Moms tend to get protected during a pregnancy yet, often in the chaos of expecting a new baby, other family members can forget important precautions. Every layer of protection surrounding a happy, healthy infant improves the opportunity to reduce exposures.

Wendy Sue Swanson, M.D., a NE Seattle resident, is a pediatrician, mother to two young boys and the author of Seattle Children’s Hospital’s “Seattle Mama Doc Blog.”