Friday, May 1, 2015

More on Vaccination: A Simple Risk-Benefit Analysis Regarding the Measles Vaccine

The other day, I took my perfectly healthy, 18-month-old son to the doctor. The nurse weighed him and measured his height (27lbs., 4oz., and 33.25"). The doctor looked in his eyes, nose, mouth, and ears, felt his abdomen, listened to his heart and lungs, asked some questions about his development. Then the nurse came back, and I held him still for a minute while the nurse swabbed his bare thigh with some alcohol and jabbed him with a needle. My son cried indignantly. I put his pants on, thanked the nurse and doctor, declined to make a further appointment at the moment (his next checkup will be when he turns two), and left the office. I buckled him and his brother into their car seats (checking to make sure their straps were properly tightened and their chest clips were aligned with their arm pits), then drove them to the park, where they played for an hour with a babysitter while I went to appointment of my own. It was a sunny, gorgeous, perfect day, and the boys had fun going down the slides, swinging, and eating a snack. I picked them up, buckled them carefully into their car seats again, and drove to McDonald's, where they ate a special lunch. Then we got back in the car and drove home, following traffic laws. I nursed the toddler in his bed, and he fell asleep and took a nap while his brother watched TV. The rest of the day was similarly uneventful.

The next day while getting the toddler dressed, I checked his thigh where he had been given the shot and couldn't find the spot where the needle went in.

Today, he is cheerfully playing with his brother in the living room. We're going to the supermarket soon. Later, we'll go see the oldest in the school talent show and have tacos for dinner.

If you're waiting for some kind of dramatic, "AND THEN," you're not going to get one. And that's the point.

I have "come out," as it were, as pro-vaccination. I believe that vaccinations are one of the greatest medical advancements and discoveries of the past several centuries. I have seen the data and charts and listened to the expert researchers. I have read articles by people who believe vaccinations are in some way harmful and do not find their arguments to be convincing. All four of my children are and will continue to be vaccinated according to the schedule recommended by the CDC and their pediatrician. The only vaccination I refuse is the hepatitis B shot at birth, because I have done my research and learned that the purpose of the newborn hep B vaccination is to prevent vertical transmission of hepatitis B from the mother. Since I know I do not have hepatitis B, I feel it is unnecessary to give this vaccination immediately upon being born. My concern is that so much happens in the first day or two postpartum that I want to do as little as possible to disrupt my new baby's simple needs to be near me and breastfeed, while still taking the recommended courses of action when medically appropriate. Thus, my children begin the hep B series at their two-month checkup, along with several other shots.

You only hear stories about people who have a story to tell. When their day is as completely ordinary as mine was, it's not interesting. And since most of the millions of children who receive vaccines each year have completely ordinary days afterward, we don't hear their stories. See, it's easy to use scare tactics to drum up public outrage and support for your cause. And when you've personally witnessed a child who had a bad reaction to a vaccination, it's completely understandable that you would be scared that something like that could happen to your own child. I get that.

The problem is, what I encounter again and again when I see anti-vaccination rhetoric is a complete misunderstanding of statistics and how they work.

For example, someone might say: "Measles was on the decline before the vaccine was introduced." But that is not a correct interpretation of the statistics. Measles deaths were on the decline, due to better sanitation and medical care, but measles cases were still quite frequent, and so were complications of measles. According to the CDC: "In the decade before 1963 when a vaccine became available, nearly all children got measles by the time they were 15 years of age. It is estimated 3 to 4 million people in the United States were infected each year. Also each year an estimated 400 to 500 people died, 48,000 were hospitalized, and 4,000 suffered encephalitis (swelling of the brain) from measles" [my emphasis]. However, "Widespread use of measles vaccine has led to a greater than 99% reduction in measles cases in the United States compared with the pre-vaccine era."

Another misuse or misunderstanding of statistical information I see frequently is the assertion that while measles has caused no (or less than a handful) of deaths in the past 15 years, the measles vaccine has caused over 100. This represents a clear misunderstanding of how statistics and risk-benefit assessments work. Consider the number of measles cases there were in 15 years, and divide the number of deaths by that relatively small number. Your result is the risk of dying from measles in this century. The number of measles cases in the United States in 2014 was almost 600, and so far in 2015 is close to 200. So let's say there were 800 measles cases in the last year and a half (in the United States - there are millions of cases of measles yearly in other parts of the world and tens of thousands die from it). As far as I can tell there have been no deaths from measles in that same period - in the United States - or perhaps one. A toddler did die of measles in Germany recently (also a First World country with good sanitation and health care). If we say one death out of 800 cases of measles, we get a risk of 1/800 = 0.00125 or about 0.1% (which was also the risk of death from measles before the vaccine was introduced). Indeed, according to studies, the general risk of dying from measles is about 0.1 to 0.2%, or 1 to 2 out of 1000. Now, the only reasonable comparison to make with this is the risk of death from the measles vaccine. To find out the risk of dying from a measles vaccine, we need to know how many measles vaccines were administered in 2014 and how many died from receiving that vaccine, and do the same math. That number is harder to come by, but we can estimate. There are close to 4 million babies born in the United States each year. About 98% of these babies will receive an MMR vaccine at age 12 - 15 months. 98% of 4 millon = 3,920,000 (3.9 million). I can't find data on how many deaths are attributed to the measles vaccine in a given year, but for the sake of argument, let's take the CDC's report that there were possibly 3 deaths from encephalitis that apparently was caused by the MMR vaccine. (If I'm reading this correctly, that's three deaths ever, not three deaths per year, so I may be considerably overestimating this number. But, for the sake of argument, let's use it anyway.) So if three infants die because of receiving the MMR vaccine, out of 3.9 million who received it, that's a risk of death of approximately 0.000001, or 0.0001%. That's much smaller than the risk of dying from measles itself. If people stop vaccinating because they believe that the vaccine is more dangerous than the disease, then we will begin seeing deaths in the hundreds again, once mass outbreaks start occurring with the regularity they did in the 1950s and 1960s.

Of course, measles deaths aren't the only concerns. There are plenty of other complications possible from measles, not the least of which is that your child will have to stay out of school for a week or two, as will all of your other children as they almost inevitably come down with measles as well. This is an economic risk more than a health risk, but it's worth considering!

Now, I understand that if your baby was one of those three that died of MMR-related encephalitis, it is no laughing matter, and knowing the stats is no comfort. But sometimes, even if we do a proper risk-benefit analysis, and we make the obviously safer choice, we might still fall into the unfortunate, tiny percentage. That's true in many areas of life.

Here's a good example of how that kind of thinking works: Let's talk about seat belts. You won't find many people who would say that you're safer if you don't wear a seat belt, right? I mean, really, almost everyone agrees that you should wear a seat belt when you're in the car and that seat belts save thousands of lives every year. Most states have laws requiring some or all of a car's occupants to wear a seat belt when the car is in motion. Very, very rarely, we hear of a case in which a person's life was saved by the fact that they were not wearing a seat belt. Perhaps the car hit a guard rail and then went into a river, and if the driver had been wearing their seat belt, they would have gone into the water, but because they were ejected from the car on the first impact, they didn't drown. Most reasonable people would agree that there is a minuscule chance of being saved by not wearing a seat belt, and this is not a reason to quit wearing your seat belt regularly. There are far, far, far more cases in which people are saved because they were properly restrained, or, tragically, they died because they were not wearing their seat belt.

If you knew that one-in-a-billion person who was saved by not wearing a seat belt, you might be inclined to think that seat belts aren't as safe as the "experts" say they are, that wearing a seat belt is actually dangerous because it can cause bruising, or that wearing your seat belt means you'll be trapped in the car after a bad crash. You might be inclined to think that because your friend survived by not wearing a seat belt, this might happen to other people, too, and you wouldn't want to be the one who keeps wearing a seat belt and put yourself in danger of dying in a similar situation to the one your friend survived.

That all sounds ludicrous, right? The same type of arguments are made with regard to vaccines. Yes, unfortunately, tragically, some children suffer adverse effects from vaccines. A very, very small percentage of babies and children have experienced severe side effects related to receiving a vaccine. (Note: Study after study has failed to identify any risk of autism from vaccines. But other vaccine injuries do occur and are noted by the CDC on their website as possible complications.) I don't take this lightly. Indeed, I think more research needs to be done to try to identify individuals who are at risk of complications so they can be protected.

A final thought on this for the day.

If my car is broken, I take it to a mechanic to fix it. I might do some quick research on the internet to find out what the likely problem is and how much I can expect to pay to fix it. I might even look to see if it's something I can try to fix myself. But it is often the case that I need someone who knows more about cars than I do to investigate the problem and fix it. Sure, I could spend weeks learning all there is to know about my Toyota, find a supplier for the parts I need, and have a go at it, but most likely I would not do as good a job as someone who is an expert in the field. I haven't seen hundreds of Toyotas with this problem. I haven't fixed it dozens of times. I don't know all the pitfalls and tricks and shortcuts that can make the task easier, more efficient, and safer. And I might end up doing more harm than good if there's actually something else going on.

People specialize in various fields and become experts in those fields. Most people cannot be experts in everything. When we need information or action regarding a field we are not as familiar with, we consult someone who lives and breathes that subject. If we don't like what they have to say, we find another expert and get another opinion from someone who also lives and breathes that subject. If I don't like the quote the first contractor gave me for replacing the floor in my kitchen, I'll call another one. I don't know how to lay flooring and I don't think I'd do a good job. If I don't like the landscape design the first gardener proposed for my front yard, I might call another gardener and get his thoughts. I don't know anything about gardening and design, or irrigation systems, or native plants, so I wouldn't trust myself to do a good job.

In a similar vein, I can do some reading on the internet about vaccines, how they work, risks and benefits, and so on, but I don't trust myself to be able to completely assimilate all of this information because I don't understand all of it. I haven't spent years studying biology, epidemiology, immunology, statistics, anatomy, physiology, and so on. The best I can do is some shallow research, learn what questions I'd like to ask, and then ask the people who have spent years studying those things, and who live and breathe this kind of work, to explain it to me as best they can. And when those experts recommend a course of action - and not just one of them, but something close to all of them - then it makes sense to me to follow that advice.

This is also my stance when it comes to other aspects of life. For example, overwhelming evidence from decades of research has concluded that breastmilk is the optimal nutrition for babies and that breastfeeding results in healthier babies and a healthier population. Thus, I advocate for breastfeeding, breastfeeding education, and breastfeeding support.

When there is more ambiguity in the research results, such as those that report on various types and effects of diet and exercise, then I read what I can and make a decision I feel comfortable with based on what we know so far. I may also consult people whose opinions I trust for what they recommend or understand about the subject.

I understand enough about statistics to look at the statistics I'm given even by people who are against vaccination and make an informed risk-benefit analysis. I am comfortable - very comfortable - with my decision to administer vaccines to my children and to have appropriate ones administered to me as well. And, from the standpoint of public health, I understand enough about how disease spreads to know that it's important for as many people as possible to receive those vaccinations.

5 comments:

  1. Hi Jessica!
    Thank you very much for this post. You are right. There are no stories that vaccination was without problems. Only bad stories are written and told. And statistics are very good. I was concerned about vaccination to my first recently born baby. And my husband are convincing me that statistics say true and vaccine helps. And everything is about probability. Without vaccination risk to be sick and have complications is higher.
    So, I'm now convinced that vaccine would be worth. Thanks a lot! I really need this kind of point to read.

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    Replies
    1. Hi!
      I'm so glad you found this post helpful. It's so easy to find articles with scary stories and misreporting of facts and so hard to find easy-to-understand articles that give more complete and correct information. I wanted to add my own bit of knowledge to the pool, as it were.

      Congratulations on your new baby!

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  2. Please check theVAERS database for a more accurate count on vaccine adverse events. (i.e. Deaths and serious risks involved with vaccines)

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