Archive for the ‘Science!’ Category

For ages I’ve wanted to write a post about science and epidemiology of vaccines, the illnesses they prevent, and the adverse reactions that can occur because of them. I am gathering information to finally do this, but it is going to take a lot of time. I’ve spent several hours yesterday and today wading through literature just on one vaccine – Hep B. I think I’m going to do this piecemeal, and then hopefully do a wrap up when it’s all said and done; otherwise, between my actual paying job and my family, it’s never going to happen. I could write books on each of them – people have written books.

My goal here is to try to put the risks of vaccination into perspective with the risks of choosing not to vaccinate. My general disclaimer stands – while I am a scientist, I am not a medical doctor. I am also not an epidemiologist, or a public health professional, or a statistician. I do my best to provide source material for the numbers I give and the statements I make, and if you want me to explain something more, just ask. I am focusing my discussion primarily on incidence data from the U.S.; this is partially because it’s easier for me, and partially because it’s more relevant to the rampant fear of vaccines in this country. My personal stance on vaccines is not the point of this, but you can read more about that here, if you want.

HepB – The Hepatitis B Vaccine

HepB is a three dose series, given at birth, 1-2 months, and 6-18 months (source: CDC vaccine schedule). It reduces the transmission of hepatitis B, a virus transmitted primarily by contact with infected blood and bodily fluids.

In my personal discussions with pregnant moms, I heard a lot of skepticism as to why HepB is routinely administered to all infants, when hepatitis B infection occurs primarily in certain high risk segments of the population – people who have unprotected sex, IV drug users, etc. A lot of people said, well, that’s not me and it’s unlikely to be my child, so why should I put my newborn at risk of an adverse reaction to the vaccine?

Ok, so that’s the rub: the HepB vaccine is incredibly safe. The primary adverse reaction is anaphylaxis (severe allergic reaction to the vaccine), which occurs in an estimated 1 in 1.1 million doses. Anaphylaxis is serious, but treatable – and because the vaccine is administered in a medical setting, the risks are even lower. No deaths have occurred because of the HepB vaccine, in the U.S. or elsewhere. HepB is part of a routine schedule of vaccinations in 179 countries – a LOT of people have been vaccinated (source)!

So what about deaths and adverse outcomes from hepatitis B? Yeah – a LOT. Before the vaccine was introduced in the mid 1980s, annual new hepatitis B infections were increasing rapidly, peaking at 26,654 new cases in 1986 (source). It is estimated that 700,000 – 1,400,000 people are currently infected with the hepatitis B virus, most of whom do not know they are infected (source). Now that HepB vaccine is administered to most newborns and young children, the rate of new infections has dropped dramatically, to 3350 cases in 2010 (source). The number of people in the U.S. who die each year because of hepatitis B infection (as in, the official cause of death) is hovering around 1700 for the last few years (source).

Most of the deaths from hepatitis B are in older people – that is, not infants dying of acute infections. Hepatitis B can cause a serious acute infection, or a chronic illness. The chronic infection and resulting liver inflammation can lead to cirrhosis and cancer – hepatitis B is one of the leading causes of primary liver cancer. So, when an infant is vaccinated, it reduces the transmission from mother to infant, as well as reducing the rates of subsequent infection later in the child’s life. As more generations of infants and children are vaccinated with HepB, the rates of hepatitis B incidence and related deaths will continue to drop.

To sum up, hepatitis B kills thousands of people every year, while the vaccine kills ZERO. Hmm.

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When I was in graduate school, I spent a semester as a teaching assistant in an introductory public health course. My duties consisted primarily of proctoring exams and leading discussion groups, but I also attended the class, mostly sitting in the back and working on my dissertation during lectures. One day, I heard the instructor, who was then heavily pregnant with her first child, begin her lecture by asking for a show of hands – who here was planning on vaccinating their children? My ears perked up immediately, as this has always been a pet subject of mine. She went on to say that she wasn’t sure, herself; shed been hearing a lot about their link to autism. Then, hand to god, she showed a YouTube video of Andrew Wakefield, proselytizing about the dangers of vaccinations. To a public health class of college freshman.

* * *

Vaccinations are the hill that I will die on, the line in the concrete, the one thing I refuse to even debate. The subject my familiars know not to bring up, not least because there is a sign that says as much in my kitchen. The thing I cannot listen to differing opinions about, because I don’t think it’s in the realm of opinion. I think it is black and white, right and wrong.

I probably shouldn’t write a word about it, but it’s a central tenant of my existence. There is a very VERY limited set of scenarios in which it is acceptable not to vaccinate. It includes people who have had serious reactions to specific vaccinations, and people who are immunodeficient in specific ways.

The efficacy of vaccinations is based on the principle of herd immunity – that, if a certain proportion of the population is immune to a communicable disease, the remainder of that population is extended some measure of immunity simply because the pathogen cannot find enough vulnerable bodies to infect.

So when someone chooses not to vaccinate their child for personal reasons, that choice can affect entire communities and populations. Herd immunity is compromised. The most vulnerable people – infants and children too young to be vaccinated, or those who are medically unable – suffer the greatest consequences, as these (preventable!) illnesses are much more serious, even deadly, for them. So – when someone chooses not to vaccinate, not only are they relying on herd immunity to cover their child’s ass, they are endangering everyone else’s kids too.

I cannot believe that this is still a topic of discussion. The autism bullshit has been so thoroughly debunked, even the media slowly (so goddamn slowly) seems to have cottoned on. And yet, there is a pertussis EPIDEMIC in my state. People (BABIES) have died. Totally preventable. Makes me sick.

And one of reasons it makes me so viscerally upset is that I know that, at least to some degree, the blame lies with the scientific community. Not just the quacks (Wakefield et al.), but the rest of us too. For failing to communicate effectively, failing to make bold statements. Scientists hate to make definitive statements – it’s not scientifically accurate to claim something is wholly true or false. Rather, we say that “evidence suggests” or “no significant elevation was observed” or something that sounds similarly evasive or inconclusive to the layman’s ear.

That basic misunderstanding between scientists and laypeople, mixed with a sensationalist media and a litigious society is a recipe for disaster. Or a pertussis epidemic, I guess.

Here are some infographics that help communicate some of the issues surrounding vaccinations:

And here is a fantastic book recommendation:
Autism’s False Prophets: Bad Science, Risky Medicine, and the Search for a Cure, by Paul Offit (amazon).
Offit has another book out that I’m psyched to read, but I gotta finish Broken Harbour first. You know how it is.

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