Understanding Vaccine Science: A Primer

By Shlomo Maital

Here is my effort to understand where we stand, with regard to a COVID-19 vaccine.

There are several different types of vaccines, each with its own strategy.

  1. Live attenuated vaccines. These use the virus itself, weaken it, and inject it; the body’s immune system is alerted and springs into action, developing antibodies that can defeat the virus if and when it invades the human body.   This is how vaccines against measles and mumps work. Measles vaccine has existed since 1950 and still is effective; measles has not mutated to defeat it.
  2. Inactivated vaccines. These use ‘dead’ viruses. Even though ‘dead’ the presence of the virus in the body activates the immune system.   Vaccines based on this approach are effective against hepatitis and polio. Polio vaccine has been effective since the early 1950’s.
  3. Subunit vaccines. These vaccines use specific pieces of the virus, key pieces, to activate immunity and neutralize the virus if and when it invades the human body. Examples: vaccines against whooping cough and shingles.
  4. Toxoid vaccines. These use toxins produced by the germs, to trigger the immunity of the body that attacks the harmful toxins. E.g. vaccines against diphtheria and tetatnus.
  5. DNA/ RNA vaccines. These are the newest types of vaccine.  

   At Emory University, in Atlanta Georgia, for example, a new type of mRNA vaccine against COVID-19 is now being tested in humans (an Emory medical student). Here is how it works: “messenger RNA” is the protein made by the virus, found on those spikes you see in cartoon illustrations, these spikes poke through the cell walls to invade the cell and use its DNA to reproduce. mRNA vaccines teach the body to produce, identify and attack those key proteins, neutralize them and hence prevent the virus from poking through cell walls.

     All over the world, desperate races are underway to develop a COVID-19 vaccine. All these different approaches are being used. Many labs are trying to use existing vaccines against related illnesses and adapt them.

   A major problem: There has not yet been a vaccine effective against coronavirus (e.g. the common cold, which is a variant of corona). And the DNA/RNA approach is relatively new and untried.

     With so many bright hard-working scientists at work day and night, there will be a breakthrough. And I believe it will come sooner rather than later. One of the key sparkplugs of creativity is desperation, and the world today is desperate for a vaccine. Add to that the profit motive – many billions of doses will be needed.