Vaccines today are a routine part of good health care. Over the past 100 years, their use and importance has increased substantially, as has their efficacy and value. Still, as a parent, it can be difficult to watch a healthy child be subject to a series of shots — especially if there seems to be little likelihood of coming into contact with the illnesses against which they are being inoculated.

Vaccines are about protecting people. Being well-informed about them can help to reduce concerns parents might have. Here, we discuss the safety of vaccines, how they work, and how they are made.

In 1900 there was exactly one vaccine available to protect people: smallpox. By age two, a child would have received exactly one shot on one occasion and that was the extent of their vaccination regimen. By 1960, there were five vaccines given in up to eight shots. In 1980, the total was up to seven vaccines but down to a total of only five shots. Today, there are 11 vaccines available. These might result in as many as 20 shots by age two.

Questions about safety can arise in the minds of parents. These are natural and reflect appropriate concern for their child. Thus, are the vaccines safe?

First, what do we mean by “safe”? If it is “free from any negative effects,” then vaccines are not safe. All vaccines have possible side effects. But if we mean “preserved from a danger,” vaccines are indeed safe as they do protect against real dangers. The approval and selection of vaccines is done on the basis of scientific studies by committees of experts, not by combining the conflicting information one might find on the Internet, parent’s magazines or bookstores.

Vaccines work by initiating a natural immune response in the body. For example, a child coming into contact with measles is likely to develop symptoms including high fever, runny nose, “pink eye” and a rash. Barring complications, the body’s defences will eventually generate antibodies to fight the infection. Once recovered, the body will maintain antibodies called “memory B cells” which will stay in the body for life.

Vaccines imitate this process, but without the messy unpleasantness and symptoms of actually becoming ill; they create an “asymptomatic infection.” There are four strategies for creating a vaccine, all with the same goal of initiating the immune reaction.

One method weakens the virus so that they reproduce poorly once in the body. Whereas a natural virus will reproduce thousands of times, a weakened virus will do so only about 20 times. This is enough to protect, but not to get sick. Examples of this strategy include measles, mumps, German measles and chickenpox.

Inactivating the virus actually kills it so the virus cannot replicate at all. Vaccines using this method include polio, hepatitis A, influenza, and rabies. A third method removes part of the virus and uses it as a vaccine against the virus. Hepatitis B is the only vaccine created in this manner. Finally, there is a strategy to use part of the bacteria against itself. Some bacteria (for example haemophilus influenzae B —Hib) cause disease by making harmful toxins. Inactivating these toxins (then called toxoid) means they can no longer cause harm.

Whether to vaccinate a child is usually a simple decision: it means reducing or eliminating unacceptable health risks and increasing your child’s safety. Not only are you protecting your own child, but you are also protecting other children from your own, should they not have been vaccinated. Vaccines are lifesaving tools. Use them for life.

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Call-out:

“Vaccines imitate this process, but without the messy unpleasantness and symptoms of actually becoming ill; they create an “asymptomatic infection.”