Vaccines are good for society. Apart from sanitation, vaccines have been the most effective healthcare measure that has ever been introduced. However, when I mention this, there is always someone who starts to attack vaccines, using shock phrases such as "corpse formaldehyde", "scandalous use of aborted embryos", "allergenic egg proteins and gelatins", "use of autism-inducing thimerosal", etc. Being neither a biologist nor a medical doctor, I am not able to answer such attacks easily. In the end, the discussion just turns into an exchange of opinion, which is useless and unproductive in this case.
First of all, the diseases that are currently preventable by vaccines, are very different in nature. If we look at the 26 diseases that are present in the WHO routine vaccination list, I think they can be roughly classified into three classes, according to the nature of their harmful mechanisms (how the disease is causing harm to the organism):
1) bacteria - the bacteria itself attacks the body and lives there at the body's expense;
2) bacterial toxins - toxins that are produced by bacteria and that harm the human body;
3) viruses - viruses use human cells to live and reproduce, and thereby harm the body by corrupting the normal function of human cells.
These three completely different mechanisms require completely different types of vaccines. It is therefore not possible to generalize about vaccines.
Secondly, depending on the nature of the disease, vaccines have very different mechanisms of action. In the case of diseases caused by bacteria, the role of the vaccine is to help the organism identify the "disguise," to use a lay term, that the bacteria uses. The body can be fooled; bacteria are complex organisms, they consist of several types of cells, and the coating cells can be sometimes very "pleasant" for our body, like in the case of streptococcus pneumoniae that causes pneumococcus. In the case of diseases caused by bacterial toxins, it is critical to incite the body (of the child usually, in this case) to start producing antibodies against these toxins before contamination. The reason for this is that these toxins spread so quickly that harm can take place before the organism even figures out how to fight them.
Thirdly, the production process of vaccines is radically different for different vaccines. For bacterial vaccines, one needs to grow the bacteria in a bioreactor, and (if required) weaken them by growing them in harsh living conditions. Since this process does not always lead to the desired result, once a particular colony of bacteria has been selected, it should be kept alive (for almost 100 years already, like in the case of BCG, against TB). Vaccines against bacterial toxins use toxoids which are the isolated and deactivated toxins produced by these bacteria (like for tetanus). Viruses, on the other hand, need cells to live on and spread. For some viruses it is possible to use animal cells to make vaccines (like for polio), but some live only in human cells (like for herpes). In this latter case, vaccines are produced using cell lines from two fetuses (aborted in the 1960s).
It is therefore not really possible to generalize about vaccines or about vaccine production processes, since they vary enormously with each type of disease. When vaccines are discussed, it is important to keep this in mind, and focus on a particular vaccine or disease.
In a few days I will post a detailed table which will summarize this information for all of the 26 diseases in the WTO routine vaccination list.
Addressing Parents’ Concerns: Do Vaccines Contain Harmful Preservatives, Adjuvants, Additives, or Residuals? http://pediatrics.aappublications.org/content/112/6/1394.full
Human Fetal Links with Some Vaccines http://www.immunizationinfo.org/issues/vaccine-components/human-fetal-links-some-vaccines
Human Cell Strains in Vaccine Development http://www.historyofvaccines.org/content/articles/human-cell-strains-vaccine-development
Growth of Rotaviruses in Primary Pancreatic Cells http://jvi.asm.org/content/76/18/9537.full
The Story of WI-38, the Other Famous Cell Line http://www.ascb.org/activationenergy/index.php/component/k2/search?searchword=vaccine&categories=&format=html&t=1385567833883&tpl=search