UNDERSTANDING VIRUSES, HOW VACCINES WORK AND SPECIALLY THE ONES AGAINST COVID-19…(PART II)

To acquire active immunity to a particular infectious disease, then we are talking about a vaccine. This biological preparation contains an agent that emulates the behavior of the disease-causing microorganism, therefore teaches the body to act against the real thing from future risk of exposure, which typically contains weakened or killed forms of the microbe, its toxins or their surface proteins. Vaccines can be preventive or prophylactic, those are aimed to prevent or mitigate the effects of future infection or therapeutic to fight a certain disease already happening on the patient.

On the other hand, vaccination is the process where the application of the vaccine take place and is the most effective method to prevent infectious diseases and increase significantly coverage of immunity across human population, some examples are the eradication of Smallpox and the control – mitigation of Polio, Measles and Tetanus around the globe and currently the World Health Organization reports that twenty five licensed vaccines are available to prevent different types of infections which include the influenza, HPV or the chicken pox to name a few.

This chart shows the vaccines with the highest global coverage among one-year-olds in the year 2018, according to the WHO. Credit: Katarina Buchholz, Statista with information from WHO.

Why we call vaccines, vaccines? Variolae Vaccinae or “smallpox of the cow” was the origin of the term created in 1798 by Edward Jenner who developed the first vaccine to denote the cowpox from their first inquiry, where describes the protective effect against the smallpox and in consequence later on, Louis Pasteur proposed to extend the term for new protective inoculations and the rest is history.

Jenner’s handwritten draft of the first vaccination is held at the Royal College of Surgeons in London.
An 1802 cartoon of the early controversy surrounding Edward Jennerยดs vaccination theory, showing using his cowpox-derived smallpox vaccine causing cattle to emerge from patients. Source: Library of Congress.

When we refer to types of vaccines, there are several as same as the strategies to try to reduce the risk of illness while retaining the ability to induce a beneficial immune response on the patient. There are at least 7 ways to develop a vaccine but the process is still improving which will derive on more types of vaccines in the future, but those elemental are as follows:

Infographic showing the different types of vaccines nowadays. Special credit to Nikitha Ramesh from the Boston University COVID-19 response corps.

Where we are on COVID-19? There is a wide variety of strategies and approaches to develop vaccines against the disease, currently there are 5 strategies for the development of COVID – 19 vaccines:

  1. DNA – RNA: Works based on molecules enabling the immune system “learn” to target specific viral proteins and act against them.
  2. Live attenuated: The same COVID-19 virus but attenuated to stimulate the immune system causing mild symptoms or none at all.
  3. Inactivated: The same COVID-19 virus but completely deactivated with chemical treatments.
  4. Subunit: An extraction of a certain piece of the virus enabling the immune system to focus on the specific factor which enable the virus to replicate.
  5. Viral vector: Use another type of virus as the “carrier” of the genetic material aimed to teach the immune system to act against the real virus afterwards.
Types of coronavirus vaccine approaches

Author: Jesus Padilla

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