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Saturday, July 15, 2017

Scientific Underpinnings of Modern Medicine - Vaccination

Summary. Our understanding of the human immune system made tremendous progress all through the 20th century, continuing even to the present day.  As part of this effort, important advances have been made in vaccine development, saving millions of lives worldwide.  But false reports linking vaccination with autism have led to rejection of vaccination by many parents, who fear incorrectly that vaccination may trigger the later appearance of autism.
Science can only proceed by open-ended inquiry, untainted by preconceived biases.  Unscientific proposals that are counter to the results of objective inquiry, such as the harmful movement to shun vaccination, are unproductive.  They harm society at large by diverting attention and wasting resources.  Human progress relies on critical verification of scientific discovery, and on building further on the progress made.

 
Allison had married relatively late, and was happy to have her infant son and husband as her family setting. 
As a parent, she’s been aware of the controversy in the popular press surrounding the question of a possible link between administering vaccines to infants and the later development of autism.  Having done considerable research on the controversy during her pregnancy, Allison realized she needn’t have concerns about this. She concluded that a possible connection with autism was mistaken. She proceeded to give all the vaccines recommended for growing children to her son, who continued growing to become a healthy child. 

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The modern practice of medicine has benefited enormously from the results of scientific research in the biological and medical sciences.  We all are better off from the results of these efforts.  The previous post dealt with the discovery of the structure of DNA and the genetic code, and the immune system.  Here I discuss the immune system in vaccination, and fallacies surrounding use of vaccination. 
Antibodies.  One of the ways that the immune system reacts to, and fights against, a foreign (likely disease-causing) particle, such as a virus, cell, or parasite, is to generate antibodies (a group of special protein molecules) that specifically react against particular structures on the particle (the antigen).   The antibodies bind molecule-to-molecule to the antigen, inactivating the particle (see the previous post) and preventing the disease or minimizing its harmful effects. 

Vaccines.  Vaccination is another process involving the immune system.  It has long been used as a way of deliberately confronting the immune system of a healthy person with a component obtained from, or that is similar to, a foreign antigen that causes disease in humans, in order to generate protective immunity against appearance of the disease later on.  The process was originally developed by Edward Jenner in the 18th century for preventing smallpox.  It was known anecdotally that milkmaids who contracted cowpox from infected cows rarely became infected with smallpox.  Cowpox causes a similar, but weaker, illness in humans than smallpox. 
Jenner’s scientific breakthrough was to take the fluid produced in the cowpox infection, and to introduce it under the skin of healthy people.  He found that the treated people did not develop smallpox.  (We now understand that his procedure induced the immune system to produce antibodies that specifically attack the cowpox- or smallpox-causing substance, a virus.  A protein on the cowpox virus is sufficiently like the corresponding protein on the smallpox virus that the human antibodies that bind to cowpox also bind to smallpox, thus inactivating it.)

Many vaccines have been developed since then to immunize people against infection from viruses or bacteria.  Today commercial vaccines contain a very small amount of a preservative to keep them sterile.  Most vaccination is for young infants and toddlers, to protect against diseases such as diphtheria, whooping cough and measles.
Vaccines and Autism.  Public fear over use of vaccines has developed over the past two decades. It started with an erroneous and misleading report of a connection between vaccination and autism in children.  (See Science (2017), Vol.356, pp.364-373.)
In 1998 a physician, Andrew Wakefield, published a report in a respected British medical journal suggesting that use of the measles-mumps-rubella triple vaccine could lead to later development of autism.  His report led to a 20% reduction in vaccinations in Britain.  But in 2004 a journalist found that Wakefield was involved in trying to patent a competing measles vaccine, which was a serious conflict of interest.  The journal, in further investigations of its own found serious ethics violations by Wakefield and retracted his original paper in 2010.  A short time later the British General Medical Council revoked his license to practice medicine at all.  Thus Wakefield’s original findings were definitively determined to be invalid.
There is also a more general suspicion by many parents of an unwelcome intrusion by government authorities into a family’s health care decisions, as well as other nonscientific fears.
More recently, the Journal of the American Medical Association reported no difference in rates of autism between vaccinated and unvaccinated children. (See Science, cited above.)

Thimerosal, a mercury-based preservative, had been used in very small amounts in vaccines until 2001, when its use was discontinued in almost all vaccine compositions.  Even so, four years later in 2005 the lawyer Robert F. Kennedy Jr. (late President John F. Kennedy’s nephew) alleged in Rolling Stone and Salon that the U. S. government was hiding evidence that use of thimerosal led to increased incidence of autism.  The data Kennedy cited were mistaken, and in 2011 Salon retracted his article. 
Both the U. S. Centers for Disease Control and Prevention and the United Nations’ World Health Organization have concluded that thimerosal causes no health problems in children. (See Science, cited above.)  By contrast, a report published online in Nature on July 12, 2017 compares social interactions of infants and toddlers among pairs of identical twins, pairs of fraternal twins, and paired but unrelated single-birth infants and toddlers.  A genetic component was detected among children in the study that later were diagnosed with autism but that was absent in normal children.  This work shows that our scientific understanding of autism is growing as rigorous investigation proceeds.

Public refusal of vaccination places the children of rejecting parents in considerable danger because the infections that the vaccines inhibit cause serious or fatal diseases.  If enough children remain unvaccinated contagion can spread the diseases among them.  On the other hand, the World Health Organization estimates that 2 to 3 million lives a year are saved because of successful vaccination programs.

Conclusion 

Remarkable advances in biological and medical science, including immunology, have been made since the end of World War II.  Among these is cancer immunotherapy, in which antibodies are created to antigens on cancer cells, as if the cancers were foreign invaders like viruses and bacteria (see the previous post). 
Immunological research has also led to use of new, effective vaccines, raising immunity to dangerous diseases in our bodies.  To our detriment, nonscientific, indeed antiscientific, campaigns against the use of vaccines in children have increased the number of susceptible children among the populations of many developed countries, including the U.S., potentially to dangerous levels.  The spread of virulent infections is enabled by the failure to vaccinate. (See Science, cited above.)

Scientific investigation seeks to expand our knowledge and understanding of the world we live in.  Reflecting on the state of knowledge at any time, a curious scientist poses a question or suggests a hypothesis.  Experiments directed toward answering the question or verifying the hypothesis are carried out as an objective pursuit, further characterizing the natural world, without introducing preconceived biases.  Conclusions are then drawn based on the new results obtained. These frequently lead to practical applications that improve our health and prolong lives. 
The intrinsic value of scientific study should be defended and supported by all to continue its progress, and to promote human welfare.

© 2017 Henry Auer