You may have heard about the “hygiene hypothesis” - people who are too clean seem to get sick more often or suffer from autoimmune problems like asthma. The idea here is that generally challenging the immune system makes it stronger – a bit like working out at the gym.
|The hygiene hypothesis: why I encourage shoe-chewing and dirt-playing|
Infective agents (bacteria, viruses, or other gross things like protozoans) make you feel sick by getting into the body, past the initial immune system defenses like the skin, and then multiplying. Symptoms that are produced, like a runny nose, are often side effects of your immune response; the infectors effectively use these gross bodily functions to spread to other hosts. Other symptoms occur because some invading organisms produce toxic chemicals that cause discomfort. Because the organisms have to multiply before you feel sick, it usually takes several days after the initial infection before you notice.
This first step after getting sick is to assign blame (as suggested by one of my grad school mentors when the lab instrument broke). Think back on all of the people you recently came into contact with who may have been sick themselves, and decide which of them is most likely to be at fault. But, that’s for another day. Back to vaccines.
The immune system is complex, and described well elsewhere; but the key to understanding the awesomeness of vaccines has to do with antibodies. Antibodies are proteins manufactured by white blood cells. Each new invading agent the immune system has not yet met triggers the production of antibodies that have a unique shape to attach to that invader, like a key fits into a lock. Once attached, depending on the kind of infective organism, the antibodies have different mechanisms for crippling them so they can’t reproduce and cause sickness. For example, an antibody might attach to a virus and stop it from entering a cell, thus preventing it from replicating.
Vaccines work in a slightly different way than the hygiene hypothesis mechanisms – more like training for a specific Olympic event: you can train all you want for the shot-put but it won’t help you win synchronized diving.
|I love not being sick|
Likewise the immune system works best, in terms of taking down an infective agent before it actually causes illness, when attacking an agent it has met before. Remember those antibodies? Every different potential infecting microbe triggers the immune system to produce specific antibodies to disarm that kind of microbe. Your body then keeps some of these antibodies in storage, like templates, for the next time it meets that same enemy. Instead of having to start fresh constructing a new antibody for a microbe the body has already attacked, the stockpile of antibodies goes on the attack immediately, and the body can make new antibodies fast enough to prevent infection since it knows the recipe already: thus you are now immune.
So, can I get around to vaccines already? Yes. Vaccines are just dead or severely crippled live microbes, small pieces of microbes, or their DNA. They are given to you orally or into the bloodstream, and the body goes into its normal immune system attack mode: make antibodies to get rid of the microbes. Your system makes antibodies, even though the vaccine microbes are either already dead or so weak that they couldn’t cause an infection anyway. But now you’ve got a stockpile of antibodies, in case you run across the actual live organism in the future. You will then be immune and not actually die or be permanently disfigured from some horrible, preventable, dread disease.
|My artistry skills may not win awards, but this is the gist. (Note: antibodies can't think and microbes don't have facial features, in case you were wondering)|
That is it. Vaccines are not some magical, scary medical invention. They are just a clever way to trick your body into using its natural defenses to protect you from becoming seriously ill.
Why else should you not be scared of vaccines? They do not cause autism. The preservative used in a few vaccines, Thimerosal, contains trace amounts of mercury at levels the FDA and WHO consider safe – less than the mercury you might eat in a can of tuna and in a chemical form that you will quickly excrete.
There is no evidence that delaying vaccinations beyond the recommended schedule is helpful - rather, this leaves your child vulnerable to preventable illnesses longer than needed. The Centers for Disease Control sets the vaccination schedule to optimize the efficacy of vaccines (sometimes they work better at a certain age), as well as their safety. Also, because we are all exposed to millions of microbes daily that our immune systems fight off, there's no way to overload your body with too many vaccinations at once.
Remember too, that vaccinating is good for other people too: you won't be a carrier of disease that you can spread to other people, particularly infants yet to be vaccinated or kids sick with cancer who can't be vaccinated.
So, go forth and get your vaccinations. Save your fear for things that are actually scary, like spiders.