How Do The Covid Vaccines Work + How Are They Different From Other Vaccines?

We may be rounding a corner in the coronavirus pandemic with the development of a couple of lifesaving vaccines, but studies show that up to 40% of Americans are hesitant to get vaccinated. There are a lot of questions about how they work and if they are safe — so we asked physician and "The Doctors" host Dr. Ian Smith to help clear up some of the uncertainty.

How do the Covid vaccines work?

"The two vaccines that have been approved for emergency use authorization in the U.S. are the Pfizer vaccine and the Moderna vaccine," Dr. Ian explains. "Those two vaccines use the same technology — something called mRNA, which is messenger RNA, which is genetic material. They do not use the live virus. They basically take the virus, duplicate some of the genetic material in the laboratory and they use that."

The Covid-19 virus has a protein called a spike protein, which lives on the surface of the virus, Dr. Ian explains. It attaches to your cells and almost forms a doorway into our cells, which allows the virus to go into your cells and replicate over and over again and overwhelm your system.

"The vaccines, however, are targeted to try to imitate those spike proteins," the doc goes on. "So what they do in the laboratory is they create genetic material that will create inside your body those same spike proteins." 

"mRNA goes into the vaccine, it gets injected into the body — it's not live, it's a duplicate," he says. "It goes into the cells. Once inside the cells, it creates those spike proteins. The purple you see [in the graphic you can see in the video above] are the antibodies that are going to fight and block those spike proteins from attaching to our cells."

"With the vaccine, we create these spike proteins, the immune system builds up an immune response. It has a memory."

(On that note, what if you've already had Covid… do you still need the vaccine? Dr. Ian answers that question here.)

How are the Covid vaccines different from other vaccines?

The Covid-19 vaccine is different from most vaccines because most vaccines inject some of the actual virus, Dr. Ian explains — not enough to make you sick, but enough to prompt your body to create antibodies.

Can you mix and match Covid-19 vaccines?

"You should not mix and match the vaccines," the "Doctors" host says. "You have to stick with the vaccine that you were given. If you're doing Pfizer, your second dose needs to be Pfizer. If you're doing Moderna, same thing. There is no mixing and matching. That's important."

Do you need both doses of the Pfizer and Moderna Covid-19 vaccines?

"The idea is you must take both [doses] that are typically separated by three to four weeks," he says. "The reason is because even though the first shot will give you some protection, in order to maximize the most protection you can get, you must have both shots. This is very key." 

"If you look at the Pfizer and Moderna vaccines that we have in the U.S.," Dr. Ian continues, "they're about 94, 95% effective. That's really, really high, by the way." 

What other Covid-19 vaccines are there?

"If you look at the Oxford vaccine, that's the Oxford AstraZeneca," Dr. Ian says. "That has not been approved here in the U.S. but is used in Europe and other parts of the world. It's a different vaccine. The Oxford AstraZeneca vaccine uses what's called a viral vector, which means they take a real, live virus, they weaken it — it's called the adenovirus, which is what gives us the cold and flu symptoms. It takes the genetic material of Covid, it puts it inside of genetic material of the adenovirus — and it's DNA, not RNA. Then, the adenovirus that's carrying the spike protein material creates the spike proteins [and] then the body builds a response."

The AstraZeneca vaccine has some advantages. "They tend to be cheaper," he continues. "Also, it's more durable, which means it's not as fragile, so you can keep it at temperatures that don't have to be freezing like we do with the two vaccines we currently have." 

"But, here's the big difference, it's not as effective," Dr. Ian notes. "The AstraZeneca vaccine is between 60 and 90% effective."