One of the keys to developing critical thinking skills is to understand the importance of addressing a point and not the person making it. Focusing on irrelevant factors like the speaker’s color, gender, ethnicity, politics, economic status, or background will leave one vulnerable to committing an ad hominem, specifically a genetic fallacy.

A few years ago, I came across a graph that purported to demonstrate that measles was well on its way out before the vaccine to combat it was introduced. It showed that the death rate from measles had dramatically declined before persons began being immunized for it. The conclusion was that the vaccine was inconsequential to the disease’s demise. To dismiss this as the ramble of an anti-vax loon would have been to commit an ad hominem. To address the point from a critical thinking perspective, I needed to examine the claim for truthfulness, then see if the whole picture was being painted, and also consider other angles.

When I did so, I learned that the anti-vaxxer’s point was accurate, but incomplete. While the death rate for measles was going down before the advent of the vaccine, the morbidity rate was not. Measles is an endemic disease, so populations can build resistance to it, but it can also be deadly when introduced to a new group. This, when combined with measles’ highly contagious nature and the susceptibility of preschoolers to it, explains why incidences of the disease spiked and descended several times, at approximately four-year intervals.

But there has been no such spike, or even a tiny bump, since the vaccine was introduced in 1964. In fact, there were 364 measles deaths in 1963, and none by 2004, a reduction of 100 percent. The anti-vaxxer’s chart showed how many persons were dying from measles, but not how many persons were contracting it. Advances in health care had enabled more persons to live with the disease, but only the vaccine eliminated it.   

Earlier this year, I again made myself examine an anti-vaxxer claim rather than dismissing it. For years, I had pointed out there was more formaldehyde in a pear than in any vaccine. But one day, I read an anti-vax blog that asked, “When was the last time you injected a pear?” The point was that the way a substance enters the body makes a difference and the blogger even noted that one could safely drink cobra venom.

And he’s correct. Swallowing the snake juice would be different from having fangs inject it into you. If one were so inclined to try the former, the gastrointestinal tract would break down the venom, similar to how the body digests proteins in food. Also, if one drank venom, it would never enter the bloodstream in active form. By contrast, when a snake bites someone, the victim has nothing beneath its skin or in its muscles to counteract the venom. Since it’s not broken down, the venom swims to the lymph glands and into the bloodstream, where it attacks the nervous system and heart, perhaps fatally.

But while anti-vaxxers are correct on these points, they again fail to understand that this has no bearing on a vaccine’s efficiency or safety. While a snakebite and a vaccine both involve injected substances, using this to compare the two is a false equivalency because one saves lives and the other ends them.   

Like the measles deaths graph, if I had dismissed the pear point because it came from someone I viewed as an anti-vax, pro-disease crank, I would have failed my critical thinking test for the day. Consider this an endorsement for avoiding echo chambers and contemplating various viewpoints. Sometimes the opposing view will be right; other times, it will be wrong, but will cause you to examine the issue and learn something you hadn’t realized. In this case, what I learned was the difference in how the body handles injections and ingestions, and the impact this has on a vaccine’s efficacy.  

The key is how much of a substance gets into the bloodstream because once it’s there, the body will process it the same, regardless of how it arrived. With snake venom, there are too many toxins for the body to handle and the poison makes its way to vital organs. While vaccines have ingredients that would be dangerous in high doses, these are in tiny amounts and toxicity is determined by dose, not ingredient. Further, venom contains active neurotoxins and vaccines do not.

Anti-vaxxers may argue that vaccines bypass the immune system, but again, they are being selective with the facts. Vaccines will bypass the body’s first line of defense, but they are designed to do so and won’t work otherwise. Vaccines contain antigens, which are dead or damaged viruses that are active enough to provoke an immune response, but too impotent to be harmful. This forces the body to develop antibodies against the real virus and thereby become immune to it. If the antigens were destroyed right away, they would never serve their purpose. Besides, antigens are not straggling interlopers, but rather they work their way out of the body like other foreign substances.

Since anti-vaxxers focus on injections, I wonder if their movement would have gained its sinister steam if it didn’t have scary needles to fall back on. What if vaccines were in chewable tablet or powder form and yielded a sweet taste as opposed to a sore arm? According to the Vaxplanations blog, the reason such an approach cannot be pursued is because oral forms of most vaccines would be incapable of getting past the gastrointestinal tract. Stomach acid, enzymes, and gut bacteria would render them useless. There are a few exceptions, such as the oral vaccines for rotavirus and polio, which work because both diseases are caused by gut pathogens.