How does the COVID-19 vaccine work?

SALT LAKE CITY — Sandra Lindsay, an intensive care unit nurse in New York City, became the first American outside of clinical trials to receive a COVID-19 vaccine on Monday.

"I feel hopeful today, relieved. I feel like healing is coming," she said, according to a report by Reuters. "I hope this marks the beginning of the end of a very painful time in our history. I want to instill public confidence that the vaccine is safe."

Lindsay is the first of many health care workers expected to receive the vaccine in coming weeks. The work to begin vaccinating Utah health care professionals will likely begin on Tuesday, as well. Utah health officials say they believe every Utah adult will have access to the vaccine by summer 2021 at the latest.

Officials at the Centers for Disease Control and Prevention explain the vaccine is another option for people to protect themselves from the coronavirus, which can lead to severe illness or death.

"Vaccines work with your immune system so your body will be ready to fight the virus if you are exposed," the agency wrote. "Other steps, like masks and social distancing, help reduce your chance of being exposed to the virus or spreading it to others."

Here's how the COVID-19 vaccine works

All vaccines work in the same fashion. They contain "weakened or inactive parts" of an antigen, such as a formation of antibodies that battled a virus, to trigger an immune response from a person's body, the World Health Organization said.

Newer vaccines, it added, typically produce "the blueprint for producing antigens rather than the antigen itself."

"Regardless of whether the vaccine is made up of the antigen itself or the blueprint so that the body will produce the antigen, this weakened version will not cause the disease in the person receiving the vaccine," the organization wrote, "but it will prompt their immune system to respond much as it would have on its first reaction to the actual pathogen."

The first COVID-19 vaccine to arrive in Utah, made by Pfizer, and the upcoming Moderna vaccine — set to be voted on by the Food and Drug Administration this week — are both mRNA vaccines. As the CDC wrote, these vaccines provide an immune system "instructions" to produce what is called a spike protein. That protein is "found on the surface of the virus that causes COVID-19."

"Once the instructions (mRNA) are inside the muscle cells, the cells use them to make the protein piece. After the protein piece is made, the cell breaks down the instructions and gets rid of them," the agency wrote.

Once that process is done, a body's immune system notices the protein on the surface of a cell doesn't belong in the body. It responds by creating an immune response and making antibodies like would happen if someone was sick with COVID-19.

"At the end of the process, our bodies have learned how to protect against future infection," the agency added. "The benefit of mRNA vaccines, like all vaccines, is those vaccinated gain this protection without ever having to risk the serious consequences of getting sick with COVID-19."

The mRNA technology is something researchers have worked with for decades even if there were no licenced mRNA vaccines in the U.S. prior to COVID-19, CDC officials added.

As you may have read over the past few weeks and months, the Pfizer-BioNTech and Moderna vaccines require two doses. The CDC also wrote the first dose increases protection while the second offers "the most protection" that a vaccine can offer.

Why do experts believe it works?

The two drug manufacturers that have completed their studies, Pfizer/BioNTech and Moderna, have each touted their vaccines as about 95% effective. Other manufacturers, like Johnson & Johnson, are still conducting clinical trials before their vaccines can be distributed.

Dr. Eddie Stenehjem, an infectious disease physician for Intermountain Healthcare, explained that clinical trials look at the efficacy of the vaccine after two months of follow-up among those who received the vaccine.

"In that follow-up data, it's shown to be 95% effective in preventing symptomatic COVID-19," he said, added that the figure from studies is "absolutely outstanding."

That said, there's still work to be done and will be done in the coming years. What's not known yet is how long protection as a result of a vaccine will last or if it will prevent SARS-CoV-2 infection or just avoid sickness from it.

In layman's terms, they still don't know if those who get the vaccine receive lifetime protection or, like the influenza vaccine, they will need future shots to be protected.

"The studies are continuing to be ongoing," Stenehjem said. "Those studies will go on for two years to really assess the longevity of the immune response as it relates to protecting us against symptomatic COVID-19."

Stenehjem also pointed out that the CDC's Advisory Committee on Immunization Practices believes all people should receive the vaccine, not just those who haven't been infected yet.

"There is a chance that the vaccine actually may provide more long-standing immunity than actual infection," he said, noting that trials have indicated that the vaccine is safe on people who previously were infected by the coronavirus.

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