Whooping cough epidemic reported in Washington State

There’s an epidemic of whooping cough under way in Washington State.

Whooping cough, also known as pertussis, is usually prevented with a combination vaccine that children receive early in life. In fact, the last time Washington State saw this many cases of whooping cough was in the 1940s, before that vaccine was even available.

Public health officials say there is nearly 1,300 cases so far this year, more than 10 times last year’s numbers.

For more information about testing for and getting vaccinated against whooping cough, visit HereandNow.org.

Dr. Jeffrey Duchin, chief of Communicable Disease and Immunizations for King County, Wash., said a number of factors could be contributing to the uptick, including a change in the vaccine. A new vaccine was created in the 90s that minimized side effects, but appears to be effective for a shorter period of time, Duchin said.

“Lots of arm swelling, certain number of seizures,” Duchin said of the old vaccine. “This vaccine was created to (produce) fewer side effects.”

There’s also whooping cough’s cyclical nature. Periods of low risk will be followed by period of high risk, every three to five years, Duchin said.

“This year we’re seeing one of the largest outbreaks in memory,” he said.

But there’s another factor as well.

“We do have a large number of people in Washington state who don’t immunize their children fully, and clearly that’s not helping the situation at all,” Duchin said.

According to a federal study of kindergarten-age children released last year, Washington State had the highest percentage of parents nationally who voluntarily exempted their children from receiving one or more vaccines, out of fear of side effects or for philosophical reasons.

“We know a large proportion of our cases are in unimmunized people,” he said. “Older kids and adults sometimes aren’t aware they’re recommended to have a Tdap, or pertussis booster, so we have many unimmunized adults, many teens haven’t yet gotten their vaccinations. So there are significant numbers of unimmunized people contributing to this as well.”

Duchin said the situation certainly isn’t so bad that if you were walking around Seattle that you’d actually notice the outbreak. And it’s certainly not so bad people should avoid the state, Duchin said.

“But, the disease causes severe illness, hospitalization and even death in infants, and that’s what we’re most worried about,” he said. “But in older children and adults, it causes prolonged cough illness that can be quite disruptive.”

From a public health perspective, efforts are focused on preventing whooping cough from afflicting infants and children. They do that by trying to make sure anyone who comes into contact with infants and pregnant women has been vaccinated, that anyone who’s sick knows to stay away from from infants and pregnant women, and that pregnant women get the vaccine as well.

“That vaccine will not only protect the newborn in the most vulnerable period in the first few months, but also will protect the mom from getting pertussis and spreading it to the baby when its an infant,” Duchin said.

In addition to those factors, there’s some concern that the pertussis bacteria may have changed over time, making it less susceptible to protection from the vaccine. It’s unclear right now, Duchin said, and deserves further study.