More Teens Getting Whooping Cough Since Vaccine Change
Monday, January 19, 2015
Aired 1/19/15 on KPBS News.
A change in the whooping cough vaccine may be contributing to more teens getting the illness.
John Bradley was training to be a pediatrician in San Francisco back in 1976 when one of his sons, just a baby, got his first whooping cough immunization.
Bradley, now the director of Infectious Diseases at Rady Children's Hospital and a professor at UC San Diego School of Medicine, remembers it well.
“He started fussing within an hour. He was just screaming. And my job as a pediatrician is to know who is sick and who’s not,” Bradley said. "And when you’re screaming, and you’re inconsolable, you’re sick.”
Bradley’s son got a vaccine different from the one that’s given to everyone today. It was called a whole cell vaccine — loaded with a purified version of the bacteria known to cause whooping cough. It did its job. It nearly wiped out the disease by the mid-1970s. But it also caused side effects.
California Whooping Cough Cases, 2014
Cases with patients ages 14 to 16: 2,006
Know immunization status of patients ages 14 to 16: 1,025
Percentage of those 14 to 16 who are immunized: 74 percent
Source: inewsource analysis of the California Department of Public Health data
“I knew (from) the data that this could cause irritability, so I toughed it out," Bradley said. "You just hold him, and they’re just screaming, and there’s nothing you can do. As a parent, you feel so bad.”
Bradley’s son screamed himself to sleep and six hours later woke up fine.
It was reactions like this that led the U.S. Food and Drug Administration to license the use of a different vaccine for whooping cough in 1996 and the Centers for Disease Control and Prevention to recommend using it a year later.
Now, with record numbers of people diagnosed with whooping cough last year — more than 1,800 in San Diego County and 10,800 in California — and outbreaks worldwide, scientists are asking why the disease is making such a vengeful comeback. The answer, in part, has to do with the switch to the new vaccine.
Ironically, Bradley was involved with the earliest research which suggested the vaccine was not as effective as experts believed.
“The vaccine doesn’t work as well we thought. The duration of immunity is not as long,” Bradley said. It begins to wane about three years after the last dose.
In 2010, the year of the first major whooping cough epidemic in California in 60 years, Bradley began seeing babies hospitalized for whooping cough. Two infants from San Diego County and a total of 10 statewide died from the illness that year.
“The babies were just the tip of the iceberg,” he said.
Bradley wondered why a vaccine-preventable disease was showing up in such high numbers.
He and his colleagues took a closer look at all the whooping cough cases in San Diego County that year. They expected to see huge numbers of unimmunized children. Instead, they were surprised to learn most had their shots.
“Our manuscript was going to be the first scientific publication that was going to question the efficacy of the vaccine,” Bradley said.
But he had trouble getting it published. One journal told him he couldn’t suggest that vaccine immunity may decrease sooner than expected.
“It’s the fear that if we say the vaccine doesn't work, then people will stop getting the vaccine,” Bradley said.
The paper was eventually published in the Journal of the Pediatric Infectious Diseases Society in 2012.
Other studies have produced similar results. And they’ve validated an inewsource and KPBS 2010 investigation, which first revealed most of the people who got sick with whooping cough were up to date with their immunizations.
In the 2014 outbreak, teenagers were among the hardest hit. They would have been among the first group of babies to get the new acellular vaccine in the 1990s.
Like 16-year-old Matthew Schaefer from Rancho Peñasquitos. He received five doses of the vaccine by the time he was 5, a booster when he was 12 and an additional booster — one not required by the state — early last year.
But he still got whooping cough in August. He was so sick he missed two months of school. The cough kept him up every night, said his mother, Paige Schaefer.
“He coughed so much he ended up throwing up,” she said.
Whooping cough, scientifically known as pertussis, is often referred to as the 100-day cough by doctors. It can cause a cough so bad you can’t catch your breath. For infants, it can be deadly.
In California last year, teens ages 14 to 16 accounted for almost a quarter of all whooping cough cases.
An inewsource analysis of state data shows that in cases where the immunization status of those teens is known nearly three-quarters had received all of their required doses.
A recent Oregon study suggests that teenagers whose first dose of vaccine was whole cell rather than acellular had better protection from the disease.
And an Australian study makes the point that a new pattern of disease is forming, with pre-teens and teens accounting for some of the highest rates of whooping cough cases. They are the first generation of children immunized only with acellular vaccine, researchers write.
Research also suggests a new strain of the bacteria, which causes whooping cough, could be contributing to the outbreaks in California and worldwide.
Andrew Preston is a scientist at the University of Bath in the United Kingdom. His research shows the bug that causes whooping cough is evolving and may have “serious consequences for the ability of current vaccines to continue to control pertussis.”
Preston has been paying close attention to the epidemic in the United States.
“As you guys in California particularly know, it’s quite possibly a mixture of things (that are causing the outbreaks),” Preston said. “Which I know sounds (like a) typically over cautious statement, but it's almost certainly the case.”
He and other scientists say many factors, such as the mutating strain and better tools to diagnose whooping cough, may be contributing to higher numbers.
Up until studies like Bradley’s, public health officials and the news media blamed parents who refused to immunize their children for the outbreaks. Research has shown they likely only play a limited role in the whooping cough epidemic, unlike the recent measles outbreak in California, which was potentially spread by an unvaccinated woman who visited Disneyland in December.
Bradley said it’s important the public trust vaccines and understand how critical they are in protecting kids against illness, but he said health officials have to be honest about their limitations. Among vaccines, the one for whooping cough has a low efficacy rate, Bradley said.
“The truth is the truth. We have to share the truth. To paint yourself in the corner saying, ‘Oh, this is a fine vaccine, it’s their fault,’ is not addressing the true problem,” he said.
Bradley said until a new vaccine is developed, health officials have to make the best use of the one they have now, including giving boosters to pregnant women to protect their newborn babies.
But he cautions, with too many boosters a risk exists that the vaccine can have the opposite effect.
“There are theoretical reasons where it may actually decrease your immunity, decrease your responsiveness to pertussis, and actually make you more susceptible to infection,” Bradley said.
Data journalist Joe Yerardi contributed to this report.
Correction: An earlier version of this story incorrectly said that the recent measles outbreak originated from an unvaccinated woman. It is believed she spread the measles. inewsource is a KPBS news partner.
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