Your Best Shot

The genetic code for the COVID-19 virus was identified on January 10 and published the following day.  With this knowledge in hand companies throughout the world set out to expeditiously develop a safe and effective vaccine for the virus.  The President’s COVID-19 Task Force predicted that it would likely be eighteen months or more before a vaccine would be approved for general use.  Many people have compared this novel coronavirus to the influenza virus.  This virus is much more contagious (at least 5X more contagious than the flu) and the world’s population has no immunity to this “novel” virus.  These factors (as well as the rising impact on the world economy) have raised the level of urgency in the quest for a vaccine.  The race for a vaccine includes over 100 prospects in exploratory or active phases of development.  It is believed that we may ultimately have more than one vaccine approved for use.  As with flu vaccines, one type of vaccine may be more suitable for certain members of society than others.  Thanks to previous groundwork the first vaccine entered human trials on March 16.  The Coalition for Epidemic Preparedness Innovations (CEPI) has been monitoring vaccine work through health officials and vaccine developers worldwide.  Vaccines are often made from a pathogen (bacteria or virus) that we wish to “protect” the body from.  Usually the pathogen itself (or some portion of it) would be formulated with other diluents into a vaccine.  The goal is to make the body’s immune system recognize the pathogen and launch an attack against it.  Most vaccines are not composed of “live” organisms but only components of the organism.  Sometimes the live organism itself may be included but in a weakened state (attenuated).  Live virus vaccines carry significantly more risk to those with weakened immune systems and to pregnant women.  The chief risk from live vaccines is catching the disease itself.  Even in healthy individuals it is not recommended that a patient receive more than one live vaccine at one time.  Vaccines have traditionally been designed to “prevent” a certain disease by recognizing the causative agent and eliminating it.  Newer vaccines are being formulated as therapeutic treatments, most often against certain cancers.  Solid tumor malignancies have a number of specific proteins (antigens) that identify the cancer.  Antibodies can be “farmed” and “harvested” in the lab to lock onto a single (i.e. monoclonal) tumor antigen thereby targeting those sites for attack by the immune system.  These antibodies can also be utilized as gateways through which additional treatment may be administered directly to the tumor (i.e. toxin or radioisotope).  Monoclonal antibodies (mAb) have gained increasing use for diagnostic testing and in biochemical purification by immunoprecipitation.  The most useful role for monoclonal antibodies is now the treatment of cancer and autoimmune disorders.

Although some of the vaccines in the exploratory phases of development are using newer experimental technology, most are relying on methods used for previous vaccines.  The first vaccine approved for human trials is a mRNA-based vaccine and is made by Moderna.  A vaccine based on the virus’ genetic sequence is believed to generate a strong immune response in recipients.  Adjuvants are substances added to a vaccine that enhance the body’s immune response to the vaccine.  This can be in the form of higher antibody levels (titers) or prolonging the vaccine’s immunity (lifetime vs booster doses required).  An adjuvant enhances immunity but does not provide immunity by itself.  Adjuvants may allow a smaller dose of vaccine to achieve the desired effect.  This could lower the overall cost of immunizing large groups of individuals and could also decrease the risk of an adverse reaction from the vaccine itself.  Several  companies involved in vaccine development are simply producing adjuvants.   Most of the vaccines in development are attempting to induce antibodies to the spike (S) proteins on the surface of the virus.  This is the protein that allows the virus to gain entry to human cells through the ACE2 receptor.   Global efforts to formulate a vaccine to the COVID-19 pandemic is unprecedented but the gains in one area need to be shared.  Attrition rates for any individual effort are around 90%, largely due to the necessary resources and money to carry a project through to completion.  The CEPI must help coordinate international R&D with the large pharmaceutical companies who have the experience and financial ability to carry an effective vaccine to widespread production and distribution.

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