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Immunity: Natural Immunity, Vaccines and Boosters Explained

written by Dr. Christine Bishara, MD - Nov 29, 2021

Photo Credit: by Nataliya Vaitkevich,
Photo Credit: by Nataliya Vaitkevich,

A lot of news about natural immunity and vaccine induced immunity has many people confused between the two. Let's talk about the mechanism of how our body builds an immune response to an infection--in this case, to COVID.

Active immunity can be acquired through natural immunity or vaccine-induced immunity.

Natural Immunity occurs when exposure to an infectious organism triggers our immune system to respond. The mechanism involves release of inflammatory mediators which allow cells such as phagocytes to engulf and try to fight the virus. This response then produces antibodies that develop against that disease. Memory cells are also produced and can recognize a virus if the body is re-infected.

Acquired immunity is developed through the introduction of vaccines that allow the body to develop an immune response.

Let's talk about COVID vaccines and how each of them works. A vaccine is a biological substance designed to protect humans from infections caused by bacteria and viruses. Traditionally, vaccines have contained live, weakened or dead microorganisms or proteins or toxins from the organism.

While some of the Covid vaccines are made in the traditional manner including the Sinopharm vaccine and the soon to be released Novavax, the majority of them are made with MRNA technology. What does this mean and how does each one work?

Below is a summary of the most common vaccines used in the US.

Pfizer: The Pfizer vaccine delivers a tiny piece of a genetic code from the SARS-COV2 virus to the host cells in the body--instructing them to make blueprints (or copies) of the spike protein. These spike proteins then infect host cells, stimulating an immune response that produces antibodies and develop memory cells that will recognize the virus when re-exposed.

Moderna: Similar to Pfizer, the MRNA genetic code sends the body’s host cells instructions for making the spike protein that will train the immune system to recognize and build antibodies and memory cells against the virus.

Johnson and Johnson: Slightly different from the Pfizer and Moderna vaccines and similar to a trojan horse phenomenon, the Johnson and Johnson vaccine introduces a harmless adenovirus to cells in a shell carrying a genetic code on the spike protein. The body’s host cells then produce a spike protein that trains the immune system to create the antibodies and memory cells.

Novavax: Not an MRNA vaccine, Novavax uses proteins in the form of nanoparticles that mimic the spike protein which elicit an immune response to the protein. Just this week, Novavax received regulatory clearance to be used as a COVID-19 booster in the United States.

A booster dose is intended to increase immunity against the antigen after memory against that antigen has declined through time. The CDC currently recommends booster shots for everyone 18 years of age and over.

Want to read more about immunity including natural immunity and how our body builds an immune response to COVID? Check out this article.

Want to strengthen your immune system naturally? Here are links to some tips and supplements to help you increase your antioxidant levels and boost your body’s ability to fight infections.

If you have a medical history or other concerns about the vaccines, please consult your family physician or a healthcare professional.



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