Whooping cough returns in Michigan

The other day, I noted a contrast between certain parts of the developed world (namely, Europe) where, thanks to fears of the MMR vaccine stoked by Andrew Wakefield and the credulous and sensationalistic British press, MMR uptake rates have fallen and, predictably, measles incidence has skyrocketed, and the rest of the world, where polio is now on the verge of being eradicated, thanks to vaccination campaigns. It’s evidence that the antivaccine movement, inspired by Andrew Wakefield and promoted by antivaccine groups like Generation Rescue, the National Vaccine Information Center, the Australian Vaccination Network, and Safeminds, has harmful consequences to public health. Of course, it’s entirely predictable that, where vaccination rates fall, vaccine-preventable diseases will tend to make a comeback. Indeed, it was antivaccine fear mongering based on religion and suspicion of Westerners that delayed progress in the eradication of polio, progress that is only now getting back on track.

Other vaccine-preventable diseases are also making a comeback, unfortunately, as I found out when I read Trine Tsouderos’ excellent article in the Sunday paper entitled Whooping cough returns as vaccine use drops, changes. The situation is a little more complex than that for the resurgence of measles due to catastrophic declines in MMR uptake in the U.K. and parts of continental Europe, but once again it’s a situation where less vaccination equals more disease. First, here’s the description of the success:

Hundreds of thousands of people in the U.S. — mostly babies and toddlers — were coming down with whooping cough each year when vaccines against “this menace,” as one newspaper called it, were introduced in the 1930s and 1940s.

A childhood scourge for centuries, this sometimes fatal disease seemed destined to become little more than a memory in the U.S. — with only about 1,000 cases nationwide over the next 40 years.

Now here’s the current situation:

In Michigan, 315 cases were reported in 2008, according to the state Department of Community Health. A year later, the incidence of whooping cough had nearly tripled to 902 reported cases. And by 2010, the number of reported cases in Michigan had risen to 1,564.

Similar outbreaks have been seen in other states as well. In California, nearly 10,000 cases of whooping cough were reported in 2010 — the most since the 1940s, according to the U.S. Centers for Disease Control and Prevention. Ten babies died.

Here’s where the complicating factor comes in. Although, as Tsouderos points out, pertussis vaccination rates remain high, there are pockets of low vaccine uptake in many states. Moreover, there is evidence that pockets of unvaccinated children can easily form the nidus for outbreaks of pertussis, measles, and other vaccine-preventable diseases, it’s about more than just that. For instance, states with lax policies with regard to religious and philosphical exemptions to vaccination tend to have elevated pertussis incidence, and the risk of developing vaccine-preventable diseases is markedly elevated in those claiming exemptions. For instance, those exempted from vaccination have been 35 times more likely to have had the measles than vaccinated children. A recent study reported that unvaccinated children are 23 times more likely to get pertussis than vaccinated children.

So what’s the other part of the equation besides pockets of unvaccinated children that allow local outbreaks to occur? Trine Tsouderos explains:

The vaccine children receive today is different from the ones introduced 70 years ago. Some of the original immunizations were “whole-cell” vaccines, made from killed whole cells of the bacterium that causes whooping cough. Eventually, those old whole-cell vaccines led to the development of the diptheria-tetanus-pertussis shot, or DTP, which became a mainstay in the school immunization routine.

“That whole-cell vaccine works well at the beginning and it lasts and lasts and lasts,” said Dr. Roger Baxter, codirector of the Kaiser Permanente Vaccine Study Center.

But, he added: “That fantastic immune response is accompanied by a, well, fantastic immune response.”

In other words, the body’s reaction to the vaccine sometimes included pain and fevers that could be, in extremely rare cases, high enough to lead to seizures, he said. “This was terrifying to parents,” Baxter said.

Of course, the fact that pertussis immunity can wane with time is touted by antivaccine activists as “evidence” that “natural” immunity is better than vaccine-induced immunity. Unfortunately, the price of “natural” immunity is a child’s actually getting the disease. That price in the pre-vaccine era was morbidity and, yes, mortality. There were 36,000 deaths from pertussis and pertussis-related complications between 1926 and 1930, and in 1934 there were 260,000 reported cases of pertussis. By 1976, thanks to the vaccine, there were around 1,000 cases. So, yes, “natural immunity” might be longer-lasting and more persistent, but the price of that “natural immunity” is death and suffering.

As is the case with so many vaccines, as the incidence, morbidity, and mortality from pertussis plunged, fewer and fewer parents had ever seen a case. Consistent with human nature, where a risk we can see is almost always more compelling than a risk we can’t, because parents didn’t know or know of parents whose children suffered–or even died–from pertussis anymore and didn’t see their children as being at risk for the disease, they became more suspicious of the vaccine and less tolerant of any possible side effects. When reports of seizures and encephalopathy from the whole-cell pertussis component of the DTP (diptheria-tetanus-pertussis) surfaced in the late 1970s and early 1980s, they led to a documentary written and produced by Lea Thompson entitled DPT: Vaccine Roulette, which first aired on a local NBC affiliate in Washington DC on April 19, 1982, and then ultimately was aired nationally on The Today Show, and then later to a book by Barbara Loe Fisher and Harris Coulter, DPT: A Shot in the Dark. Both used anecdotes over epidemiology and were very compelling at causing fear. As Steve Novella pointed out, later evidence did not support an association between the whole cell pertussis component of the DTP and encephalopathy, but the damage had been done.

Fortunately, scientists developed an acellular pertussis vaccine. These vaccines didn’t have the same side effects of fever, febrile seizures, and the like, but recent evidence suggests that they are probably not as good at producing long-lasting immunity as the old whole cell pertussis vaccine was. It’s a trade-off, as is all vaccine development. The very aspect of the whole cell pertussis vaccine that allowed it to produce longer-lasting immunity was the very aspect of it that also resulted in more side effects:

Developing vaccines can be a balancing act, trying to trigger as good an immune response as possible in as many people as possible for as long as possible without also triggering unacceptable side effects.

“You can make a safer vaccine and people have better trust in it,” said pediatrician Dr. Kathryn Edwards, director of the Vanderbilt University Vaccine Research Program, but the unwanted side effects — like fevers and pain — can be associated with better, longer-lasting protection.

Antivaccine activists use this observation as an excuse to claim that the pertussis vaccine “doesn’t work” and that “natural immunity” is much better. However, even immunity from a pertussis infection wanes over time, and, more importantly, as I pointed out earlier, the price of this “natural immunity” is the disease, with all its attendant risks, up to and including death. Faced with that tradeoff, I’d say that vaccination makes far more sense than taking the risk of disease. One has only to look back nearly 80 years, when a quarter of a million people per year were developing pertussis and thousands of them died. While it’s true that medicine has advanced a lot since then and the mortality rate from pertussis would likely not be nearly as high, the suffering from the disease is still incalculable, as anyone who’s seen a baby with pertussis coughing and struggling for breath would attest.

When it comes down to it, arguments from antivaccine activists that the pertussis vaccine “doesn’t work” and the argument that, if the vaccine is so effective, then why is pertussis making a comeback are a smokescreen. Vaccination resulted in a massive decline in incidence of pertussis. When reports 30 years ago suggested that the vaccine wasn’t safe enough, a safer vaccine was developed. The tradeoff was that its immunity is probably not as long lasting. However, given how safe the vaccine is, that characteristic of the vaccine only suggests that booster shots at an older age are a good idea, not that we should abandon the vaccine. Yet that is the argument that antivaccine activists are making, with their characteristic binary thinking: That if the vaccine isn’t perfect and doesn’t provide immunity as long-lasting as the disease, then we should abandon the vaccine and promote “natural” immunity. Just never mind the cost.