Bacillus Calmette-Guerin (BCG) Vaccine

The story of the bacillus calmette-guerin vaccine is a very interesting one and the true account of the tuberculosis (TB). First, that is redundant; bacillus calmette-guerin is vaccine so there is really no need to include “vaccine” when talking about. Also for simplicity it is usually referred to as BCG. Now what makes the story so interesting was how it came about. It has examples of great reasoning but also of sloppy research. It is that duality that makes it so neat.

Smallpox

The story really starts with smallpox, not TB. Back before there was a vaccine for small pox it was a veracous killer of men. It was discovered that by exposing someone to cowpox, not deadly in humans, that the body would build an immunity to it and when then exposed to smallpox that that person would be immune to it aw well. Now smallpox has been eliminated in nature and exist in a few high-containment labs like the Centers for Disease Control in Atlanta.

Following that logic it seemed like the same might be able to be done with bovine tuberculosis. The logic seem sound however the found out that the bovine TB was just as bad as human TB. Oops. They still continued to study the bovine TB by growing it on an artificial medium. What the found out was that after several generation of living on the medium that the virus lost its voracity and was safe to use on human as an immunity builder.

Its use in the United States was almost over as soon as it began. One of the first groups to receive the vaccination was a group of 400 newborns (under 10 days old). Suddenly they started getting sick with 74 of them dying. What had gone so wrong? This is our sloppy science part of the story. It was later determined that the innocuous strain had been keep in the same incubator as one of the deadly strain. Cross-contamination occurred. Basically the children had been given a potentially deadly virus. Overtime the American public started to accept it but much more care was taken with the virus after that.

Even though now it is considered safe, there has never been a push to vaccinate large groups. The US is considered a "low TB" country so there was no need to. It is given on case by case bases to those most at risk and to people with certain ailments that the vaccine does help. It helps with leprosy, Multiple Sclerosis, badder cancer, and even type 1 diabetes

One last odd little factoid about BCG is with it's efficacy. It is different from country to country though, in general, it becomes less effective as you get closer to the equator.