The 2011 measles outbreak and vaccines in Nature

I was debating what to blog about last night, and it wasn’t easy. We’re in the midst of yet another embarrassment of riches, as far as topics relevant to this blog go. Then I noticed something that I considered to be quite appropriate, given that we are now right in the middle of the yearly autism quackfest known as Autism One in Chicago. This week, Nature published an issue with a special section devoted specifically to vaccines. The timing seemed just too deliciously appropriate to ignore. Think of it. In Chicago (well, Lombard), there is a collection of anti-vaccine cranks meeting to present fallacious “science” claiming that vaccines cause autism and all manner of chronic health problems. In contrast, one of the oldest and most distinguished scientific journals in existence publishes several articles in a single issue about vaccines.

Yep, karma, even more so, given that the CDC published a new Morbidity and Mortality Weekly Report (MMWR) last week discussing the status of measles in the U.S.

The Nature vaccine issue has a number of articles on the topic of vaccines, ranging from an editorial, to news items, to scientific articles. For my purposes, three articles caught my attention:

The article discussing the case of measles is particularly relevant today, as we are in the middle of a resurgence of measles cases, both here in the U.S. and a much worse outbreak in Europe. In the U.S. we have had thus far this year 118 cases of confirmed measles, the most cases since 1996. Of these cases, 47 resulted in hospitalization and 9 in pneumonia. Fortunately, none had encephalitis, and none died, but that’s only because the risk of encephalitis is between 1:1,000 and 1:5,000. In an outbreak of 118, there’s only around a 10% chance (at the most) of having a case of measles encephalitis among the children. However, the more children there are who are infected, the greater the chance of complications such as encephalitis, and let’s not forget that we already have an 8% pneumonia rate.

Fortunately, MMR vaccine uptake in the U.S. remains generally high, although there are increasingly pockets of low uptake susceptible to outbreaks. Indeed, that’s what appears to be happening. As reported in Nature and the MMWR report cited above, measles was in essence eliminated from the U.S. in 2000. This was not easy to do; measles is one of the most contagious viruses that exist. Indeed, it’s the contagiousness of the measles virus that has allowed it to find its way back into the U.S. from other countries, as described in the MMWR report:

Among the 118 cases, 105 (89%) were import-associated, of which 46 (44%) were importations from at least 15 countries (Table), 49 (47%) were import-linked, and 10 (10%) were imported virus cases. The source of 13 cases not import-associated could not be determined. Among the 46 imported cases, most were among persons who acquired the disease in the WHO European Region (20) or South-East Asia Region (20), and 34 (74%) occurred in U.S. residents traveling abroad.

More worrisome, of the 47 hospitalized patients, all but one were unvaccinated, and the statistics were:

Unvaccinated persons accounted for 105 (89%) of the 118 cases. Among the 45 U.S. residents aged 12 months−19 years who acquired measles, 39 (87%) were unvaccinated, including 24 whose parents claimed a religious or personal exemption and eight who missed opportunities for vaccination. Among the 42 U.S. residents aged ≥20 years who acquired measles, 35 (83%) were unvaccinated, including six who declined vaccination because of philosophical objections to vaccination. Of the 33 U.S. residents who were vaccine-eligible and had traveled abroad, 30 were unvaccinated and one had received only 1 of the 2 recommended doses.

Do you see the pattern here?

Leaving a child unvaccinated leaves that child at a greatly increased susceptibility to measles and therefore a highly elevated risk of catching the virus when exposed. This is particularly true when enough people refuse vaccines to compromise herd immunity, so that the unvaccinated can no longer rely on the herd, which they’ve gotten away with doing in the past. Nowhere is this more evident than in Europe, where more than 6,500 cases were reported in 2010, and we have Andrew Wakefield to thank for decreased vaccination rates that are only now starting to recover, as this story in–of all places–The Huffington Post describes:

To prevent measles outbreaks, officials need to vaccinate about 90 percent of the population. But vaccination rates across Europe have been patchy in recent years and have never fully recovered from a discredited 1998 British study linking the vaccine for measles, mumps and rubella to autism. Parents abandoned the vaccine in droves and vaccination rates for parts of the U.K. dropped to about 50 percent.

The disease has become so widespread in Europe in recent years that travelers have occasionally exported the disease to the U.S. and Africa.

Although overall vaccine uptake rates are high, thanks to Andrew Wakefield, there are pockets of children whose parents fear the vaccine more than measles and have therefore not vaccinated. These pockets have been enough to allow measles not just to come roaring back in Europe, but to allow Europe to export its measles to the U.S.

Perhaps the most interesting perspective this week on the issue of vaccine rejectionism is the second article I cited above, Vaccines: The real issues in vaccine safety by Roberta Kwok, who notes in the beginning of her article that “hysteria about false vaccine risks often overshadows the challenges of detecting the real ones.” She begins by citing the case of John Salamone. We’ve met him before in the context of my review of Paul Offit’s most recent book, Deadly Choices: How the Anti-vaccine Movement Threatens Us All. Salamone’s son is an example of a real adverse reaction to a vaccine. Basically, his son got polio from the live oral polio vaccine, a known complication. His son got that vaccine, even though an inactivated polio virus vaccine known to be safer was available at the time, because the oral polio vaccine was cheaper and more easily administered. As a result, Salamone became a real vaccine safety activist, in contrast to the anti-vaccine activists at Generation Rescue masquerading as “vaccine safety” activists. He and other parents worked together to effect change, and the U.S. shifted to the safer vaccine in the late 1990s.

Kwok’s overall point is that these fake vaccine safety scares, such as the widespread belief that vaccines cause autism, have made it more difficult to identify real vaccine safety issues:

Vaccines face a tougher safety standard than most pharmaceutical products because they are given to healthy people, often children. What they stave off is unseen, and many of the diseases are now rare, with their effects forgotten. So only the risks of vaccines, low as they may be, loom in the public imagination. A backlash against vaccination, spurred by the likes of Andrew Wakefield — a UK surgeon who was struck off the medical register after making unfounded claims about the safety of the measles, mumps and rubella (MMR) vaccine — and a litany of celebrities and activists, has sometimes overshadowed scientific work to uncover real vaccine side effects. Many false links have been dispelled, including theories that the MMR vaccine and the vaccine preservative thimerosal cause autism. But vaccines do carry risks, ranging from rashes or tenderness at the site of injection to fever-associated seizures called febrile convulsions and dangerous infections in those with compromised immune systems.

Serious problems are rare, so it is hard to prove that a vaccine causes them. Studies to confirm or debunk vaccine-associated risks can take a long time and, in the meantime, public-health officials must make difficult decisions on what to do and how to communicate with the public.

The article then goes on to describe how public health officials have become increasingly vigilant about vaccine side effects, setting up intensive surveillance systems, most recently and famously for the 2009 H1N1 pandemic. Specifically, scientists were looking above all for evidence of a link between the H1N1 vaccine and Guillain-Barré syndrome, based on studies that suggested a link between the 1976 swine flu vaccine and this debilitating neurological syndrome. Studies thus far have not shown a link between the latest H1N1 vaccine and Guillain-Barré, which is good, but vigilance continues, not just for H1N1 vaccines but for every vaccine. The result of this surveillance has been to find a link between a rotavirus vaccine and intestinal intussusception, as well as a link between the measles, mumps, rubella and varicella (MMRV) vaccine and febrile convulsions. As a result, use of these vaccines was halted.

Unfortunately, links are often not clear, and during the period of uncertainty between the first report of a possible vaccine complication and studies that either confirm or refute the link, public health officials are forced to make decisions on incomplete evidence. One current example is the possible link between the H1N1 vaccine Pandemrix and narcolepsy in young people. It is not yet clear whether this association is spurious or likely to indicate causation. Another aspect of this issue is whether there are genetic susceptibilities to adverse reactions due to vaccines. Contrary to what the anti-vaccine movement claims, scientists have never denied that there might be genetic factors resulting in increased susceptibility to vaccine injury. However, in science actual evidence is required, rather than speculation, and what we have now on this issue is, for the most part, speculation. It’s also not at all a straightforward issue to determine genetic determinants of increased risk for adverse reactions. Just as finding a genetic cause of autism has been difficult and full of dead ends, despite clear evidence of a strong heritable component, finding evidence of a genetic predisposition to vaccine injury is anything but a trivial task. Moreover, even in children who might have such a hypothetical predisoposition to vaccine injury, when the risk-benefit calculation is done it may well end up that the benefits of vaccines still outweigh the risks. Such would seem to be the case for children with mitochondrial disorders.

So how do we convince parents that the fear mongering by the anti-vaccine movement about vaccines and autism (or vaccines and all the other the movement tries to link with them, for that matter) is without basis in evidence and science and that it is safe to vaccinate? I agree with Julie Leask is at the National Centre for Immunisation Research and Surveillance, Discipline of Paediatrics and Child Health, School of Public Health, University of Sydney, New South Wales 2006, Australia, who wrote the last article that caught my interest, Target the fence-sitters. This is the way to go; the hard core anti-vaccine believers are not going to change their minds, no matter how much evidence you throw at them. We’ve seen this time and time again right here on this very blog, right here in the comments, stretching back over six years.

That’s why it’s a waste of time and effort to try to change the mind of the likes of J.B. Handley, Jenny McCarthy, Barbara Loe Fisher, Ginger Taylor, and others. There was a time when I thought that I could, but six and a half years of beating my head against the wall has taught me that I’m about as likely to succeed in changing their minds as I am to convince the Pope to become an atheist. It’s just not going to happen; these people are true believers in what, for all intents and purposes, can be considered a religion. The bottom line is that I don’t really care about changing, for example, J.B. Handley’s mind; I only care about countering his influence whenever possible. The fence-sitters can still be reached. They haven’t (yet) fallen down the rabbit hole of pseudoscience, autism “biomed,” and conspiracy mongering. There’s still hope to reach them, and reach them I try to do, using a variety of techniques ranging from pure sarcasm and full frontal assault to humor to dispassionate discussions of scientific papers. What works the best? I really don’t know, because I have no way of measuring. I do, however, keep trying.

In the meantime, as the MMWR report on the 2011 measles outbreak in the U.S. and the articles in Nature demonstrate, the anti-vaccine movement is doing real damage as it reverses hard-won gains made against measles over the last four decades.