Some good friends are having their first child in a few months. In addition to making decisions about breast-feeding, co-sleeping, and whether to let the baby use a pacifier, they are also concerned about which vaccinations to give their child. Although many of their vaccine-related questions have been answered by speaking with their doctor or looking at reliable medical Internet sources, there is one question that still bothers them. The couple came across information showing that the number of vaccines given to children today is much greater than the number given in the past. They also read on an antivaccine movement website that the developing immune system of a newborn baby or young child is not equipped to deal with this number of vaccines. They came to the following conclusion:

The number of vaccinations given to children today is too much for the average immune system to handle.

Questions

1. We know that the human brain undergoes rapid development during infancy and early childhood.
In fact, newborns have a membrane-covered gap between their skull bones, called the fontanelle, or soft spot, that accommodates a brain growing faster than new bones can form. Does the immune system have structures that similarly change after birth or is it fully formed at birth?
2. How does the immune system get better at fighting disease, with age or with exposure to substances that cause an immune response?
3. Vaccines given a few decades ago contained whole, intact viruses that had been exposed to heat or chemicals that rendered them inactive. Do most modern vaccines contain entire viruses or small parts of a virus like a cell membrane protein?
4. Which would cause the generation of more kinds of antibodies, the whole viruses present in vaccines of old or the parts of viruses present in modern vaccines?
5. Consider your answers to questions 1–4 and explain why the original statement bolded above sounds right, but isn’t.