Science Says: 'How are infectious organisms weakened for vaccines?'


By Eric Arts, PhD

Question: How are infectious organisms ‘weakened’ for live vaccines?

“Our first primitive attempts to vaccinate people against a killer virus probably started along with human civilization. About a 1,000 years ago in India, someone figured out if the person next to you came down with small pox and didn't die, it was a good idea to pop one of their blisters and smear the pus on himself/herself, which apparently became common practice. (This may also be the origin of the phrase, "what doesn't kill you, makes you stronger."). But seriously, this is the basic idea behind a 'weakened' pathogen as a live vaccine.

It took another 700 years before English physician Edward Jenner basically proved that this century-old practice of 'vaccination' actually works—but he used the pus of small pox blister of infected cows and proved protection from infection from human pox.  Believe it or not, someone actually volunteered to prove the effectiveness of this vaccine: "Sure, Dr. Jenner—I totally buy into your idea that this cow zit scratched into my skin will completely protect from the deadly pox disease that just killed my neighbour. Let me be your first volunteer, pleaseeee!"  

Another 300 years later, Jonas Salk and Albert Sabin were working frantically on two different vaccines to prevent polio. Salk advocated that only a dead version of the polio virus would provide the proper safety and adequate protection from the disease, but a few years later, most of the world was receiving a more effective attenuated polio vaccine developed by Sabin. The Sabin vaccine was prepared by growing the polio virus on a non-human ‘food’, such that this virus lost its taste to kill and paralyze humans, but still grew enough to let our immune system know that this foreign invader was not welcome.  

We have come a long way in 1,000+ years of immunology. Modern medicine and very exhaustive clinical trials have provided us with very effective and extremely safe vaccines for at least a dozen deadly pathogens (vaccines that are weakened versions of the nasty bugs). These vaccines have saved millions, if not billions of lives, and moved us far away from the hit-and-miss protection of smearing organic pus on our arms. Unfortunately, many of the ‘civilized’ and ‘educated’ people in world today prefer to ignore the reports from hundreds of thousands of volunteers and researchers who have dedicated their lives to ensure safety of vaccines and protection from disease. They prefer to believe the opinion of science skeptics who falsified data to win the attention of the public or celebrities that continue draw attention to these pseudoscience enthusiasts.”

Eric Arts, PhD

Eric Arts graduated with an Honours Bachelor of Science from Western University in 1990 and then received his PhD in Microbiology and Immunology from McGill University in 1994 under the supervision of Dr. Mark A. Wainberg. Following post-doctoral training in the Division of Infectious Diseases at Case Western Reserve University (CWRU), Cleveland, Ohio he joined the Division of Infectious Diseases at CWRU as an Assistant Professor in 1997 and became a full Professor in 2009. Dr. Arts' previous administrative experience includes Director of the Evolution in Medicine Program for CWRU (2010-2014), Director, CWRU Centre for AIDS Research (CFAR) Uganda Laboratories (2002-present), Sub-Program Director, Cancer Virology, CWRU Comprehensive Cancer Centre (2004-2006), and Director of Development, Centre for AIDS Research, CWRU (1998-2002).