Who's to blame for the whooping cough outbreak?

Julia Bellus answers reader questions on vaccines

You asked, Science-ish answered: This is the second installment of a Science-ish series on vaccines inspired by readers’ questions. Listen to part one, a Science-ish podcast, here.

For a long time, the anti-vaccine lobby got away with a hell of a lot in the press. We gave a quack-based minority equal air-time with the science-based majority. Just read some of what’s been written on the media’s role in perpetuating theories about the supposed MMR-autism link.

Today, it seems with every outbreak of a vaccine-preventable disease, the blame rests squarely—or “disproportionately“—on vaccine deniers who ought to know better. Take whooping cough, the bacterial infection of the lungs that causes a violent cough-vomit combo and sounds like (be prepared for it) this. In recent years, epidemiologists have been tracking a spate of worrying outbreaks, and the incidence of whooping cough is on the rise in Canada and elsewhere.

This wasn’t always the case. After the vaccine was introduced in the 1940s, the incidence of pertussis dropped from epidemic proportions to almost zero. But now the 100-day cough is back again, and alternative-medicine types, especially the ones who consider oregano oil “the natural way” to stave it off, are being fingered.

As much as vaccine deniers may be insufferable to the Science-ish audience, do they really deserve all the blame?

Science-ish called Dr. Scott Halperin, an internationally regarded pertussis expert based at Dalhousie University in Nova Scotia. “Microorganisms are living organisms,” he said over the phone. “They are evolving and so are we. When an outbreak occurs, it’s usually multiple different factors that contribute to it.”

That’s the case with whooping cough, he explained. For a long time, people thought immunity from both the disease and the vaccine would last a lifetime. Science evolves, and researchers now know that’s not the case. In fact, immunity from the vaccine isn’t even lasting for as long as was originally anticipated. “People hoped it would last 10 years,” said Dr. Halperin, “and it’s lasting about six.”

According to a September New England Journal of Medicine study, involving several hundred kids in California, protection against whooping cough wore off during the five years following the fifth dose of the vaccine in childhood. That means that by adolescence, some people will be susceptible to getting the disease again.

Another contributor to the outbreaks: The kind of whooping cough shots we use now—called the diptheria-tetanus-acellular pertussis vaccine—are safer but also weaker than the previous vaccines. So adults are supposed to get a booster. But many aren’t bothering, said Dr. Halperin. “The estimated uptake of the vaccine is only about five to seven per cent in adults.”

This means there’s an unboostered at-risk adult population that’s partly to blame for spreading the bacteria around. As this article in the PLoS blogs network explains, the adult epidemic is made worse by the fact whooping cough often masquerades as a regular cough in grown-ups, partly because of residual immunity from childhood. There are fewer complications from pertussis in adults, and side-effects are milder—but the cough is still very contagious, and spreadable to infants and children who can die from the illness.

Until an improved whooping cough vaccine is approved and recommendations are changed to reflect the latest science, Dr. Halperin suggested keeping up to date with your immunizations. And of course, not to become a vaccine denialist. “We certainly can’t blame all of what’s going on with whooping cough on people who are vaccine refusers,” said Dr. Halperin, “but they are not making the situation any better.”

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Maclean’s, the Medical Post and the McMaster Health Forum. Julia Belluz is the associate editor at the Medical Post. Got a tip? Seen something that’s Science-ish? Message her at julia.belluz@medicalpost.rogers.com or on Twitter @juliaoftoronto