May 6, 2014 in Features, Health

Shadle Park graduate leading CDC effort to prevent meningitis, pertussis

By The Spokesman-Review
 

Before joining the CDC, Dr. Tom Clark attended Emory University in Atlanta, where he trained as a pediatrician.
(Full-size photo)(All photos)

As potentially fatal illnesses that spread easily, meningitis and whooping cough are diseases that make the news when infections spread.

Behind the headlines, a Shadle Park High School graduate is leading efforts to identify and stem the illnesses’ outbreaks.

Dr. Tom Clark, Shadle’s 1988 valedictorian, heads the branch of the Centers for Disease Control and Prevention that investigates outbreaks and devises plans to contain them.

Both illnesses – tracked in the same branch at the Atlanta-based agency because they’re both bacterial and preventable by vaccines – have challenged investigators in recent months and years. Outbreaks of meningitis B have popped up on college campuses and elsewhere, while whooping cough epidemics have prompted questions about the vaccine that’s supposed to prevent it. Clark, who initially trained as a pediatrician, said he does the work because it lets him help people on a larger scale.

While the job involves managing a team of 20 epidemiologists and communicating to the public, “his main job is science, and that’s what he is really superb at,” said Dr. Stephen Hadler, deputy director of the CDC’s Division of Bacterial Diseases and Clark’s boss.

Amid outbreaks of meningitis B, a dangerous strain, late last year at two universities, Clark and his team petitioned the Food and Drug Administration to let an unlicensed vaccine be delivered to thousands of students. His work coordinating large-scale inoculation campaigns at Princeton University and University of California, Santa Barbara, included explaining to parents why the government wanted to give their children vaccines approved for use overseas but not in the U.S.

In the aftermath of whooping cough (aka pertussis) infections that reached epidemic levels in 2012 – Washington reported its highest number of cases since 1942 – his team worked to identify its causes. The state has some “pockets” of undervaccination, Clark said, but his team thinks the bigger problem is that the vaccine’s protection wore off.

“It’s not completely clear why the immune response is not working the way we want it to,” he said. “There’s a lot of unanswered questions in terms of how to make vaccines that protect longer.”

‘You knew the wheels were turning’

Clark, now 44, was a standout student in Spokane.

“Tom was one of those quick studies, one of those kids who caught on easily,” said Hank Mendoza, a biology teacher at Shadle who taught him. “You knew the wheels were turning in his mind, because he would ask questions that were not typical of what kids would ask. They were deeper questions: ‘What if this happens? How come X and Y?’ ”

Clark attended Emory University in Atlanta, where he trained as a pediatrician. But many children he saw as a doctor in training had problems larger than their immediate complaints, he said, such as family disruptions that affected vaccine schedules or health insurance that came and went.

With an eye on addressing those large-scale problems, he attended Oregon Health Sciences University (now Oregon Health & Science University) in Portland to study public health.

He joined the CDC and learned more about epidemiology, the study of how disease spreads and can be controlled, eventually becoming acting chief of his branch.

“Making evidence-based vaccine recommendations translates into millions of kids getting vaccinated every year rather than just the hundred that come through your clinic,” Clark said.

‘Protection wearing off’

Those large-scale results require a big-picture view of the nation’s health.

While the CDC’s immediate, on-the-ground response to bacterial meningitis is over at the two universities, the illness continues to pop up and prove fatal, notably among gay men in Los Angeles and New York.

Clark said he and his team are working to make sure they’re ready to administer vaccine again in case of another outbreak.

In the fight against whooping cough, he turned his focus to his home state.

Washington was among states hardest hit by pertussis during the 2012 epidemic.

By the end of the year, the state had reported 71.3 cases per 100,000 residents, the fourth-highest rate in the nation, according to CDC data.

State and local health officials ramped up vaccination efforts, noting the importance of “herd immunity.” People who can’t be immunized for medical reasons or because they’re too young can be better protected if the people surrounding them are immunized.

That community immunity suffers when more people decide against getting their children vaccinated. In Spokane County, the percentage of parents receiving vaccine exemptions for their children – getting them legally excused from being immunized – was up in the 2010-11 school year compared with a decade earlier, according to data from the state Department of Health. (It was about 6.4 percent, compared with 4.3 percent in 2000-01.)

But while going without vaccination raises the risk of getting whooping cough, Clark said, “we think probably the bigger problem is just protection wearing off, probably because we switched over to a different type of vaccine.”

Washington is among “universal purchase” states, buying all the vaccine that goes to all residents 18 and younger.

“Because of that, Washington switched over vaccines pretty early in the process, late in the 1990s,” Clark said. “And so we think that might be part of why the outbreak happened in Washington. More kids had gone a longer time since using those newer vaccines.”

The old wholesale pertussis vaccines – made of killed bacteria – contained the entire bacterium that causes pertussis. Parents reported they made children fussy or feverish, and some lost confidence in the vaccine because of some rare occurrences of neurological problems in kids who’d received it, although it was never clear whether the vaccine caused those problems, Clark said.

The new pertussis vaccine, part of a shot known as Tdap, used just part of the bacterium to make it safer. 

The vaccine does protect children, Clark said. Vaccinated kids are very unlikely to get serious disease.

But as for how long it works: “You never really know until you use them at public health scale. Pertussis is just so transmissible that even small decreases in duration of protection or effectiveness kind of translate into big changes in the epidemiology of disease.”


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