Atomic Nerds

This is a guest post from my friend Indy, currently working on her master’s in public health after her first in biostatistics and genetics. Who is also rather fed up with seeing the concept of herd immunity abused, usually in service of justifying Why My Kid Doesn’t Need To Be Vaccinated. She’ll be around in comments to answer questions, too. Take it away, Indy.

As most of you have probably noticed, there’s been a lot of coverage in the last decade and a half about what’s politely termed “vaccine non-compliance.” What you might have missed, however, is that the tone of that coverage has started to change rather dramatically in the last few years. Media coverage in the 2000’s focused on isolated cases, the uncertainty about adverse events, vaccine schedule spacing, the theoretical link (and the disproving of said link) between vaccines and autism, and, in some cases, what the future might look like if vaccination rates continued to drop. The coverage in the past few years has been about that future – we are now living in an era of major communicable disease outbreaks. Measles, mumps, rubella, polio, and whooping cough are all making a comeback in a big, flashy way; Google any one and you’ll find at least several cities with major outbreaks going on at the moment. The World Health Organization (WHO) just declared an international state of polio emergency. These outbreaks have become international in scale and are impacting every other continent (save Antarctica) in addition to the US. (If you’d like to explore this further, check out the map here: interactive vaccine map. Start out in 2008 and then jump forward in time to 2011 and beyond. Or just look at the contrast between “all” and 2008.)

In addition to billions of dollars in health care costs, they’re taking lives; in the US, this number is currently just shy of 1400 for deaths between June 3, 2007 and June 14, 2014.1 This may not seem like many, but consider that it’s about half the number of deaths from the World Trade Center bombings. This is also approximately double the number of unintentional firearm deaths in children (ages 1-14) between 1999 and 2010, and there are massive public policy campaigns currently going on to reduce that number.1 Furthermore, this number is isolated to the US. I’m a US scientist and I work with US data sources, so I’m pretty dependent on the CDC; some countries in Europe have death tracking systems similar to those we have in the US, others don’t, and in Africa, we have to rely predominantly on WHO data. In short: given infrastructure constraints, there are decent ways of estimating how big outbreaks are in other world regions, but not great ways of carefully tracking the number of vaccine preventable deaths on a global scale. But we can conclusively say that got a very, very big problem on our hands.

This brings us to the multi-billion dollar question that’s really the point of this post: why are we suddenly seeing such massive outbreaks of vaccine preventable diseases when, in most places, the majority of parents are still vaccinating their kids? The answer, in a nutshell, is herd immunity. You’ve probably heard this term before, and many people have a general idea of what it means, although sometimes the colloquial definition is just flatly wrong. Herd immunity, in a very broad sense, is the protection granted to a few individuals without immunity when the majority of the population has immunity. In order to talk more specifically about it, though, we’re going to have to use some nitty-gritty disease science.

There are two concepts that are central to the workings of herd immunity. The first is an R0 value (pronounced “R-nought” in the world of biology and disease) and the second is an SIR model (pronounced as an acronym (S-I-R), although epidemiologists might have more fun if we’d called it “sir”). These provide two similar but slightly different ways of understanding herd immunity. Let’s start with the SIR model. SIR stands for susceptible-infected-recovered – in short, the three categories a person can fall into. You can either lack immunity to a disease, be infected with a disease, or be recovered from a disease (and thereby have immunity to it). If a disease has never been introduced to a population, everyone sits in the susceptible class. If we’re looking at what scientists call a “metapopulation” (a large population made up of small populations) a disease might have moved through some small populations but not others, so some people might be recovered, some people might be immune, some people might be susceptible. The general idea behind an SIR model of an outbreak is that eventually, every susceptible person will contract the disease, move into the infected category, and then either move into the recovered category or die. Once a disease has swept its way through a population, there’s simply nowhere else for it to go in human hosts and it dies out in that particular population. So why do we see diseases persisting over time? Firstly, because of that whole “metapopulation” thing – a disease might have burned its way through one population, but it’s probably still working its way through another, and secondly because of this pesky tendency humans have toward reproduction. When humans have babies, they’re effectively putting people directly back into the susceptible population. When that number climbs high enough, the disease is able to gain a stronghold in the population again, and you see another epidemic. This is why infections in populations tend to have a cyclic nature; time elapses and the susceptible category rebuilds itself. If you’re interested in a real world example, San Juan Pueblo in New Mexico can provide one.3 (Full disclosure: this example and the citation are from a human biology course I took a few years ago.) Smallpox first broke out in San Juan Pueblo in late 1700s (around 1780). Another major epidemic occurred about 35 years later – enough time for the susceptible population to have built up again. So what does all this have to do with vaccination? Vaccination performs a neat trick – it moves people in the susceptible class directly to the recovered class, completely skipping the infected stage. In this way, we can move babies and children directly from susceptible to “recovered” (or immune) and the susceptible population never moves above a certain level. The majority of our population is immune, the susceptible population is too small for diseases to move in, and we’re safe. Phew. But why does the size of the susceptible population matter? Here’s where we get to R0’s.

An R0 value is the basic reproductive number of a virus or bacterium – it’s the number of people an infected person will infect provided that no one around them has immunity. It’s a shortcut for understanding how rapidly a disease can spread through a population. There are a lot of parameters that go into this value, depending on things like population density and disease dynamics, but the long and short of it is that some diseases have higher R0 values than others. Most of the “big bad” diseases that are vaccine preventable have really high R0 values; measles can be as high as 18, mumps can reach 14, rubella’s high is 16, and pertussis’ (whooping cough) is 18. The 1918 flu (as bad as it was) had a maximum R0 somewhere around 3, so even diseases with relatively low R0 values can be major problems if the majority of the population is susceptible.2 It’s worth noting that similar data aren’t widely available for many common domestic animal diseases, but rabies has an R0 of around 2 (not surprising given that its method of transmission is the rare act of biting). Scrapie (a sheep disease which involves, well, the delightful case of sheep eating other sheep bits) has an R0 around 4.5 It’s reasonable to assume based on human diseases that spread in similar ways that respiratory viruses such as distemper and viruses that are spread via surface contact (such as canine parvovirus and feline panleukopenia) have higher R0 values than these; these types of diseases are referred to as “highly contagious” across veterinary literature. A Swedish study in the 1980s on canine parvovirus infection found that epidemics of parvo could continue as long as there was a concentration of 6 unvaccinated dogs per square kilometer.6 Given this, it’s starting to seem obvious how big outbreaks can start. One person infects 18 others? That’s a fast moving disease. So what do you do with a disease like measles? How do you stop an R0 of 18? (How do you solve a problem like rubella?) In short: you make sure every person the infected case has contact with can’t catch the disease. This is herd immunity. If a person with measles would infect 18 people, but all 18 of the people who might become infected are immune, the chain of infection stops with that individual. No one else gets measles, and there is no outbreak. This is a great thing from a public health perspective, but it’s a really crappy thing from a vaccine compliance perspective. In order to achieve herd immunity for diseases like measles, mumps, and polio, vaccine rates have to be above 90%. (Sometimes it’s more in the neighborhood of 95% - diseases with high R0 values are incredibly hard to stop in their tracks.4) (As an aside, this number is the “critical proportion”, “pc”, or the minimal immunization coverage needed in a population to eliminate infection. It’s found as the simple equation [MATH] 1-1/R0. [/MATH] Sorry for the equation.) As vaccination rates have dipped, diseases are able to gain a foothold. We have a two-fold problem on our hands: the susceptible population is too high, and we have diseases with really high reproductive numbers that can infect very large numbers of people. Diseases jump back into populations, find a big, thriving susceptible population, and start infecting away. Voila: you have yourself an outbreak.

So why is herd immunity such a hot topic, given all of this crazy disease math? It’s because most people have very mistaken ideas about susceptible population sizes, R0 values (if they know what they are at all), and needed vaccination rates. Most people think that if we vaccinate the majority of people (oh, say, 50-60 percent) then their kids (or themselves, or their dogs, or their pink flamingo lawn furniture) will be protected by the nebulous “herd immunity.” (This, by the way, is why when Amanda Peet called parents who didn’t vaccinate “social parasites,” I agreed with her. Sure, it was a rude way to phrase it, but it’s exactly what’s going on – people are relying on others in the community to keep themselves safe and to derive benefit.) But sadly for them and even more sadly for everyone else, that’s just not how it works. When we need vaccine compliance rates of 95%, everyone has to vaccinate to keep the susceptible population low enough. But, but, but, someone out there is starting to say, there’s still 5%! Can’t I be in that 5%? Firstly, everyone thinks they can be in that 5%, then we end up with really low vaccination rates and the same problem to begin with. And secondly, the medical community needs that 5% buffer because not everyone can be vaccinated. People with compromised immune systems. (See: children with leukemia.) People who are actually allergic to vaccines. People who have chronic infections. Cancer patients. Some AIDS patients. That buffer is being used, and it’s being used by people with a significant need to avoid vaccination. So in short: herd immunity is not going to provide protection, and lack of vaccination has lead to its failure over the last decade or so.

There are a lot of reasons to vaccinate your kids, self, dog, and pink lawn flamingo. Some of them are medical. (You don’t want polio.) Some of them are logical. (There is no link between autism and vaccines, and vaccine side effects are exceedingly rare – the likelihood of having an adverse event is much lower than your likelihood of getting measles if you don’t vaccinate.) Some of them are ethical. (You don’t want to give measles to a childhood cancer patient.) Some of them are social. (Most public health professionals, myself included, believe that we have an ethical obligation to the communities that we live in to vaccinate.) But this one is, simply put, mathematical. We have to keep the susceptible population low enough to prevent outbreaks, and we’re not doing it. It’s putting people in very real danger for no real benefit. So vaccinate your kids, yourself, and your pets. (And now that you understand all this epidemiology math, explain it to people on airplanes. You’ll be doing the world a favor, and they’ll leave you alone with your book.)

1a. There are a couple of sources for vaccine mortality data. I’m using anti-vaccine body count, which is calculated from CDC’s weekly morbidity and mortality reports, but CDC Wonder’s Mortality database would provide the same data. And would be named after a slightly less inflammatory celebrity.

1b. Gun death statistics are from CDC Wonder.

2. Data here are predominantly from our friend the CDC again, with the exception of the 1918 flu number which is from Fraser et al. 2009. “Transmissibility of 1918 pandemic influenza”. Nature 432 (7019): 904–6.

3. Aberle SD, et al. 1940. “The vital history of San Juan Pueblo.” Hum Biol 12: 141-87.

4. http://www.cs.berkeley.edu/~daw/teaching/c79-s13/slides/0319-diseases.pdf

5. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1689932/pdf/10380685.pdf

6. http://www.sciencedirect.com/science/article/pii/0167587783900326

So this is, again, late, but this took awhile to finish distilling through the mental filters.

There’s this football team that plays in the Washington D.C. area. They’re called the Washington Redskins, their uniforms are a dark maroon shade, their logo is a profile of a Native American* man, and their mascot looks like this:

A lot of people, particularly Native Americans, feel the name and additionally the logo and mascot are offensive. The Redskins are of the view that this has been their name and their color scheme and their logo for a long damn time, there’s a whole army of Redskins fans out there, and changing any of it because a minority finds it offensive is entirely unreasonable. They also feel that it’s an admiring and respectful use, given football teams don’t name themselves after anything that is wimpy and pathetic, they name themselves after strong, aggressive images.

Recently the U.S. patent office ruled that as the moniker and logo are “derogatory to an ethnic group”, the Redskins trademarks are invalid. This doesn’t mean, by the way, that people can actually go out and bootleg Redskins merch left and right now- at least not yet- though Harry Reid seems very confused on this point himself. (Harry Reid, litigator, has no clue about the law; film at eleven.)

I have Views on all of this. As follow:

The patent office thing is a total bullshit bureaucratic move, a rather craven roundabout way to try and strongarm the team into doing the thing that the government would prefer politically. It’s a rather classic case of “technically correct, blunderingly wrong in actual fact”. It’s stupid and a thing the federal anything should not be doing, an entirely righteous generator of outrage from a libertarian perspective. I do not approve in the least.

That said, sorry, but the Redskins name, logo, and mascot actually ARE pretty goddamn offensive and in my opinion the team should have done this of their own free will long ago. Why? Well, it’s my damn blog, so I’ll tell you, at length.

1. The historical usage of the term “redskin” ain’t all that nice. There’s a lot of linguistic argument that the origin of the term and most of its usage weren’t, much of which is justified, but at the time the team was named and for the bulk of RECENT history, yeah it was. In the middle of the twentieth century it was usually used about like “negro”- if a common phrase in a genre of movies had been “THE NEGROES ARE ATTACKING” or reflections on the noble savagery of the negro. I’m sorry, but it’s just not a polite term. The context in living memory has been a lot more “racist” than neutral or “admiring”. To claim otherwise is the revisionism. Go watch a few weekends’ worth of Westerns from the thirties through the sixties and seventies and then come back and tell me that “redskins” usually meant “our awesome neighbors”.

2. Using a group of people as a mascot is pretty fucking sketchy in and of itself. The NFL has 32 teams. 15 are named after animals (Bears, Lions, Panthers, Rams, etc). 4 are named after jobs identified with the region or city their team hails from (Packers, Steelers, Cowboys, 49ers, the former Oilers as a bonus). 3 more are named after some combination of job and group identity, again associated with the dominant population of the region their team hails from and in one case a highly admired identity throughout (foundational to) America’s history (Vikings, Buccanneers, Patriots). There are a handful more named after more esoteric or generic things (Browns, Saints, Jets, etc), and 2 named after mythological humanoids (Titans, Giants). And then there’s two named after an extant, resident ethnic group in the United States, the one at issue having by far the more derogatory name and mascot. Not coincidentally, the same group. (And no, the Vikings aren’t just the same thing. For one, there’s a huge Scandinavian population in Minnesota. For two, in order to compare to “Redskins” it would have to be “Ignorant Thuggish Norsemen”, for which there isn’t a derogatory term in common American parlance for reasons that should be obvious if you ponder the matter.)

3. Arguing that the history of the Redskins franchise has always been totally respectful and it’s just modern overweening sensitivity targeting a convenient target with the “racism” charge is, like arguing that “redskin” is a neutral or respectful term, bullshit. The Redskins were the last NFL team to integrate and allow black players on their roster- in 1961. And not of their own decision, either- the .gov told them they could either integrate or they could GTFO Washington D.C. and the stadium they were using, seeing as how it was all federal property.** The Redskins as a franchise have had to be shoved, struggling and protesting, toward any sort of respect for people who aren’t parts of the NFL. Or ones that are but aren’t white enough.

4. Speaking of D.C. and federal land, does it seriously strike nobody but me that naming the D.C. football team a derogatory term for the only ethnic group the American government fought an actual official war of extermination against is incredibly fucking cringeworthy? Really? Just me? Okay.

5. I’ve heard complaints that the Redskins shouldn’t change their long-held name because of the complaints of “a tiny minority”. Okay. A) Native Americans themselves are kind of a tiny minority in the US, just under 1% of the population, b) There are Natives that don’t care, though suspiciously every single one I’ve met personally finds the “Redskins” thing ridiculously offensive whether or not they think it should be a political priority, c) Dismissing Natives as a minority so tiny that they shouldn’t really have significant political sway is pretty goddamn tasteless given the people brushing them off and the city the Redskins are based out of are pretty much the reason they aren’t the ethnic majority in the first place.

6. Speaking of political sway, it matters in just how grating and how big of a problem something is. I’d be pretty irked with a team called the “Bitches” that featured a furious-looking woman with her teeth bared as their mascot, but it stings a lot less given that women have the political power to put a hell of a lot of pressure on to have it changed. Likewise I hate being described as “flyover country”, or any variant of hick or rural rube or redneck by snotty liberals from blue urban enclaves with the implication my opinions should be dismissed out of hand, but much to the frustration of these individuals me and mine have the political power to blow off THEIRS at least half the time and more often at our own local level. Shrugging off group-based insults is a hell of a lot easier when your group actually has the power to hit back hard over more serious abuses. Native Americans, for the most part, don’t.

7. And still speaking of relative power and minorities: “Washington Redskins” is about as offensive as a Richmond-based team in a black uniform with a portrait of a brutish-looking black man called the “Bucks” would be. You will note there is no such team. You may also note that the NFL has a pretty high proportion of black players, coaches, and staff. Also that black people represent a much larger minority in the US than Native Americans do. You would probably also be able to draw the conclusion that this is not a coincidence. There are, so far as I can determine, only slightly more actual Native players in the NFL as there are teams using them as a name and logo. You can’t really talk about reclaiming derogatory terms when the actual people they refer to aren’t even remotely represented among the almost entirely white people using them. You can’t actually “reclaim” a term on someone else’s behalf. Especially when they really don’t want you to.

I’ve seen the charge “white liberal guilt” thrown around a lot. On a more personal note? My objection is not in the faintest based on guilt over being white. It was what I was born as, I feel zero guilt for things I did not personally do, the sins of my father’s fathers are not my sins. I was, however, raised by my parents to not be an asshole, and THAT is why I find the “Redskins” thing offensive and why I think they ought to change of their own initiative. Not because it’s more or less popular to do, not because either a minority or a majority thinks it’s good or bad, not because white people ought to slink around whispering apologies for what our ancestors and government have done, because using people as mascots, ignoring the objections of the people they represent in favor of what’s more comfortable for you to do instead, willfully dismissing the history behind it all, and telling those people in the process how they ought to feel about it are asshole things to do.

The Redskins have, and should have, every protected right to go around being assholes. The beauty of freedom is that you can stand up and take your place as a proud Asshole-American and go prancing about in redface with a cartoon warbonnet if you so choose. And given that Native Americans are a tiny population, you’re probably not even going to face any consequences for it at all beyond people like me saying “Jesus, what an asshole”. They have to right to whine about being called assholes if they so choose from their megaphone; they have the right to say “Well fuck you, you’re too puny for me to care about”.

“Have the right” and “right thing to do” are totally different things, however.

*Before “politically correct” starts up: a) “Indian” is already an ethnic group from India and having to verbally distinguish between the two irritates me, b) I don’t see what the hell the harm is in calling a group of people what they actually want to be called, especially when it’s clearer, and c) of all the hyphenated-American ethnic terms, which I have mixed feelings about, “Native American” is the one that is actually accurate rather than redundant as a descriptor. We’re all Americans, but they’re the group that was here in the millions strong on the actual American continent before History Happened. “Politically correct” is a pretty pointless charge when it’s also geographically and anthropologically correct.

**I DON’T disapprove of this on libertarian grounds. “My house, my rules” is an old and respectable principle, and if they had really wanted to stick to their guns they were free to- as long as they found someone else willing to host them, or bought their own stadium.

Discovered floating in the tubes:
The Naked Bike Ride In Portland Showed Everyone’s Vulnerabilities

More or less safe for work. I don’t really know where to start. Well, no. That’s not true. Let’s start with this: Pick a fucking message you goddamn hippies! By the time your point is this muddled, you’re not protesting, you’re just a bunch of streakers egging each other on.

Let me be clear. There is nothing wrong with being a bunch of streakers egging each other on, but please don’t try to tart it up as some noble crusade. Ok, oil dependence? The bikes make sense. Body image? The naked makes sense. Naked for oil dependence? You lost me. Bikes for body image? Are you saying people should stop being fatties and exercise more? Nice, hypocrites. (Yes, that’s in sarcasm font.) Being naked to show vulnerability on a bike, to the cold mechanical predations of cars? Well, ok, but you all put yourself in that position voluntarily. And what does being squishier than a chevy have to do with oil dependency?

Seriously people, if you’ve got a thorn in your ass over something, be specific! Look at anti-abortion protests. Sure, they suck, but they’re specific and focused and you don’t have to guess what they’re on about. If you have to explain what you’re protesting, you’re not only doing it wrong, but nobody will remember or give a shit five minutes later.

After you get enough groups in the tent, you’re just having a good time with vaguely like-minded people. Again, nothing wrong with that, just don’t expect to be taken seriously.