Different types of vaccines work in different ways to offer protection, but with all types of vaccines, the body is left with a supply of “memory” cells that will remember how to fight that virus in the future. The two front-runner COVID-19 vaccines, developed by the drug companies Pfizer and Moderna, are made with a technology that has been tested but never before licensed for a vaccine in the U.S. This is called messenger RNA, or mRNA. Many vaccines put a weakened or inactivated germ into our bodies to trigger an immune response. Instead, mRNA vaccines teach our cells how to make a protein that triggers the production of antibodies, which protects us from getting infected if the real virus enters our bodies. Here’s how it works:

BY CAT HO AND TODD TRUMBULL | DEC. 15, 2020 12:00 P.M.

Scientists looked at the entire genetic sequence of the coronavirus and isolated the genetic instruction, or RNA, for making the “spike” protein, one of many proteins on the outside membrane of the virus. The spike protein resembles a crown and gives the coronavirus its name.

They produced a synthetic copy of that genetic instruction and encased it in a lipid, an oily substance that helps it get inside human cells. That gets injected into a person’s arm.

The synthetic genetic material prompts the body’s own cells to produce the spike protein, which the body’s immune system recognizes as foreign.

After the spike protein is made, the cell breaks down the mRNA strand and disposes of it using enzymes in the cell. The mRNA strand never enters the cell’s nucleus or affects genetic material.

The immune system then mounts a defense to the spike protein, producing antibodies and other defenses to fight the virus.

The Pfizer and Moderna vaccines are given in two injections, weeks apart. The first shot starts building protection. The second shot is needed to get the most protection.

The Pfizer vaccine’s most common side effects were fatigue, headache, muscle pain and chills, according to an FDA analysis. The side effects for the Moderna vaccine, which is expected to be the second to gain FDA authorization, are similar.

The side effects of a coronavirus vaccine are felt more strongly than the side effects from a flu vaccine because the former is prompting an immune response very quickly after the injection. There will probably be more pain and swelling at the injection site for the coronavirus shot than what most people are used to with the flu shot.

Sources: Chronicle research, CDC, Pfizer, Getty Images

 

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