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The country is in a race against time.

Public health officials are trying to vaccinate as many people as possible to limit how many Americans get sick and die and to stop the virus before it mutates and becomes even harder to stop.

There is a second race that will become even more important as time goes on: the task of quickly convincing people that the vaccine is safe. Right now, tens of millions of Americans have yet to commit to taking the vaccine. Many others are not eligible for the vaccine, including everyone younger than 16.

We spoke to two researchers in Pittsburgh about this challenge. Whichever spreads faster — the vaccine or the virus; vaccine science or vaccine misinformation — will determine whether many thousands of Americans live or die. We combined the interviews for clarity and brevity.

Paul Duprex is the director of the Center for Vaccine Research at the University of Pittsburgh, and Matt Moffa is the director of infection prevention at West Penn Hospital.

What do we know about how the vaccines work?

Moffa: What both  the [Pfizer and Moderna] vaccines do is they target the spike protein of the coronavirus. We’ve all seen pictures of the coronavirus by now. You know the circle with the little spikes around the edge. And those spiked proteins are what the virus uses to attach to our cells and cause infection.

Duprex: You take the mRNA, which encodes the spike protein. You inject in the mRNA and you use the body of the vaccinated person to make the proteins. Because we’re only bringing in the mRNA, which makes the spike, not the mRNA that makes the whole virus, we teach the body what the spike looks like on the virus, but we don’t cause the disease.

That’s the basic premise of vaccination: Have the person who’s vaccinated or their body believe that they’ve seen the virus before, but not get the disease so that whenever they meet the virus that gives them the disease, they’re ready for it.

How do we know the vaccine is safe?

Moffa: Both vaccines were found to be about 95 percent effective against symptomatic infection. So what that means is they study different endpoints of patients that became symptomatic and then they test them to see if they have COVID-19. And 95% of them were the group that didn’t get the vaccine.

The most common side effect with both of these vaccines is a sore arm. That’s usually the site of injection, typically relief through over-the-counter pain medication. Others got low-grade fevers, chills, headaches, fatigue. These are all actually signs that your immune system is is working for you and creating antibodies

Duprex: Even though they don’t work 100%, they still give us protection and it’s better to get a vaccine than it is to get the disease.

Why did both Pfizer and Moderna use mRNA vaccines instead of traditional vaccines?

Duprex: The answer to that question is speed. And it is unsurprising that the first vaccines that were licensed were mRNA vaccines. You didn’t have to grow the virus and inactivate it. That’s a typical way that we make vaccines.

One worry you hear among people afraid to take the vaccine is that, even if it appears safe now, they worry that the mRNA vaccine will stay in our bodies and could cause harm down the road.

Moffa: Your body quickly degrades it after it’s applied. There’s absolutely no integration with our nucleus or our DNA, which is one of the things you see from anti-vaccination misinformation campaigns: “It alters DNA.” It absolutely does not alter DNA.

What’s the process like for people who take the vaccine?

Moffa: We’ve had an open room that’s been spaced out. Everyone goes in, reads through the instructions of the vaccine. The factsheet provider then cleans off your arm, gives you the vaccine, and then we go to another room like a large auditorium that’s spaced out and everybody’s observed for at least 15 minutes to make sure there’s no reaction. And then after that, you’re on your way.

If there are pockets of people who geographically or politically decide not to take the vaccine, will those groups be more vulnerable to getting sick?

Moffa: We know that in populations that decide not to get their children vaccinated, they become little hotbeds of measle outbreaks. So the same thing usually happens with this or any other virus.

Once people get vaccinated, can they go back to life as they knew it before the pandemic?

Duprex: They could have no coronavirus symptoms, but they could still be infected with coronavirus. And if they are in the presence of someone who hasn’t had the good fortune of getting the vaccine, they could transmit the virus to that person, even though they’re perfectly fine themselves.

Moffa: We know that vaccines clearly prevent symptomatic infection. But you can put two and two together and kind of figure out that this will likely also prevent transmission. But how much transmission would it prevent? We don’t really know that information.

Duprex: Until we have widespread vaccination, until all of the people who would like the vaccine get the chance to be vaccinated, good practice and good societal behavior is even for the people who have been vaccinated to mask up so that they don’t put anyone else at risk.

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