Shawnee physician explains how Pfizer, Moderna vaccines work

By Vicky O. Misa | | (405) 214-3962 | Twitter: @Vicky_NewsStar
The Shawnee News-Star
Four lanes are set up outside of the Citizen Potawatomi Nation's (CPN) FireLake Arena, as the area continues Phase 2 of COVID-19 vaccine distribution. Appointments can be made online at and distribution is set up for Thursdays from 9 a.m. to 4 p.m. at the arena.

As Phase 2 of the COVID-19 virus vaccine rollout has officially begun, it's natural to wonder how these two vaccines managed to show success so quickly.

SSM Health St. Anthony Hospital-Shawnee Dr. Gregory Grant said the two vaccines approved and currently being distributed — Pfizer and Moderna — are both mRNA-based.

“The thing about mRNA is that it's been around a while,” he said. “It was discovered about the same time as DNA.”

The health care industry started trying to use that technology to cure disease 10 to 12 years ago, he said, with some success.

“It's pretty amazing that within just a month of these two vaccines being approved, a lot of our Shawnee health care workers have already had both shots,” he said.

Grant added there are at least 40 or more vaccines still undergoing trials.

mRNA-based vaccines

According to the Centers for Disease Control and Prevention (CDC), mRNA-based vaccines contain material from the virus that causes COVID-19 that gives cells instructions for how to make a harmless protein unique to the virus. After the cells make copies of the protein, they destroy the genetic material from the vaccine.

“Our bodies recognize that the protein should not be there and build T-lymphocytes and B-lymphocytes (defensive white blood cells) that will remember how to fight the virus that causes COVID-19,” the CDC website reads.

Grant said the mRNA-based shots are basically giving the body instructions on how to make its own vaccine.


Grant said residents receiving the vaccination will get a dose through a needle in the arm, and then get a second dose, also called a booster, weeks later.

“The Pfizer booster is usually given three weeks later,” he explained. “Moderna's is about four weeks later.”

He said the time period between the two shots doesn't have to be exact, so residents shouldn't stress, if for some reason they miss the window, but it is optimal to aim for that goal.

“Full immunity is achieved two weeks after the second dose,” Grant said. “The vaccines are showing 95-percent effectiveness, that's considerably more than what flu shots can generally offer.”

In a good year, he said, flu shots can achieve around 50 percent effectiveness; some years, if the flu shot misses the mark on what strain is prevalent, the rate can be considerably lower, like 30 percent or less.

Grant said many viruses mutate, so it isn't unusual to encounter multiple strains.

“These COVID-19 vaccines will be effective against all of the strains because of how they work,” he said. “The part that changes or mutates does not affect how the vaccine functions.”

He did say it's too early to tell if the COVID-19 virus vaccine will need to be an annual thing, like flu shots are, since not enough time has passed to determine how long it remains effective.

“It has shown effectiveness for six months so far, because that's how long we've had to watch it,” Grant said.

But even with that, the vaccine is already protecting residents twice as long as natural antibodies are for those who have become infected.

“When people who have gotten the virus make those antibodies, we are seeing those antibodies only stick around for about three months,” he said. “So the vaccine is really recommended, because it's already providing protection much longer.”

Grant said, of those infected, residents who have experienced more severe cases produce more antibodies than those with milder cases, so the level of natural protection can vary a little.

In the long run

There is still a long road ahead, Grant said.

Things will only begin to slow down or level out once 80 percent of the population has either been infected or vaccinated.

“It's going to take some time,” he said. “The more places that can offer vaccinations (as the vaccine becomes more readily available) the faster we can get there.”

Grant said it is vital that — even after vaccination — residents continue to wear their masks, exercise hand hygiene and keep cleaning and disinfecting.

Right now Phase 2 of the vaccine rollout is underway.

Each Thursday, at Citizen Potawatomi Nation's (CPN) FireLake Arena, distribution is between 9 a.m. and 4 p.m. by appointment only.

To schedule an appointment for the vaccine, visit

“We'd like to direct the public to register and schedule through the website and call 211 if they need assistance in registering,” Sara King, Community Health Education and Planning Lead Region 6 County Health Departments, said.

Watch for updates.