Many parents fear that a vaccination might make their child sick. While vaccinations can cause mild reactions in some children, these consequences are typically rare and minor. This is a fear that might still be lingering from decades ago, when vaccines were first developed. Children today are not administered the same vaccines that your grandfather was given many decades ago. The vaccines of today work better, and they have significantly fewer side effects. Overall, the advancement in vaccine production has rendered worries about illness as a result of vaccination obsolete.

Dead or Alive

Vaccines are usually formulated using a “killed” version of the infectious agent being vaccinated against. It is impossible to get the infection itself from this type of vaccine. Most vaccines fall into this category, and parents never have to worry about their children getting sick from the vaccine.

However, it is also true that a few vaccines, including vaccines for chickenpox, the measles, mumps, and rubella, are made using live viruses. The live viruses in these shots have been greatly weakened. While it is possible for these “live” vaccines to cause a very mild case of the infection, they cannot cause a normal infection. In other words, no one who is vaccinated against chickenpox gets chickenpox from the vaccine, though there is a small chance that the vaccination might cause a mild fever and a slight rash. No one becomes very ill from these live but weakened viruses.

One of the biggest rumors out there is that the flu shot will make you come down with the flu. It's unclear how this myth originated, but it has absolutely no scientific backing. Every year, the flu vaccine is formulated from particles of the various flu viruses in existence. This formulation can change, depending on which flu strain is most virulent and therefore most likely to make people sick. As a consequence, the flu vaccine does not contain a whole flu virus of any particular strain, alive or dead. There is therefore no way that the flu shot can make you catch the flu. A fear of catching the flu from the flu shot is like the fear of being run over by a pile of hubcaps.

It is true that some people might experience flu-like symptoms after the vaccine, but they are not getting sick from the flu. The difference is that the symptoms are very short-lived (lasting for a few hours), and they are mild. These feelings never cause any life-threatening complications that the flu virus itself can cause, such as pneumonia or a brain infection.

Weakened Immune System

Some parents worry that by using a vaccine to protect their child from an infection, they might be weakening the child's immune system. If the child can't get sick, they reason, the immune system has no work to do. As a result, it might become too weak to fight off infections. It is impossible to vaccinate against every illness-causing virus on the planet. Consequently, a child's body is regularly exposed to plenty of infections that challenge the immune system and force it to stay strong and active.

On the other side of the coin, it is important to remember that the infections for which vaccines are now available were once considered dangerous. Chickenpox, for example, is not considered a serious illness today, but that is because children of recent generations have had the benefit of a vaccine against the disease. Children used to die from chickenpox before the vaccine became widespread. So while withholding a vaccine does force your child's immune system to work harder to fight off infection, there is always the chance that the infection will be too strong for a child's immature system to vanquish. Most children who get chickenpox do survive, but the process of getting a viral infection such as this is not benign. It's not a good idea to let your child get sick from an infection instead of protecting him with immunization.