To talk about vaccination, Jill Riley called on an expert: Kris Ehresmann, Minnesota Department of Health director of infectious disease epidemiology.

Every Wednesday morning at 8:30 CST, Jill connects with experts and local personalities for some real talk about keeping our minds and bodies healthy — from staying safe in the music scene, to exercising during a pandemic, to voting and civic engagement. Looking for more resources and support? Visit our friends at Call to Mind, MPR's initiative to foster new conversations about mental health.

I just want to jump in and talk about the vaccine for COVID-19 — whether it be the Pfizer vaccine or the Moderna vaccine — and just to start, kind of an overview of the technology.

Both of these vaccines use a new technology involving messenger RNA. RNA is genetic material, and what it does is, it actually provides a message to our cells: instructions on how to create a protein. That sounds very simple, but the protein that our cells create using this information mimics or matches a protein that is on the surface of the SARS CoV-2 virus, and so by instructing our cells to make this protein, what we're doing is we're creating a situation in which our immune cells say, hey, this is foreign, I'm going to develop antibodies. In that process, we've now developed immunity.

It's a situation in which there's no virus that's included, so this isn't like most vaccines where you have a weakened or dead germ that's being used to create an immune response. It's really instructing your cells to make something that mimics the virus, that your immune system will recognize when it's confronted with the virus, but it's not the virus. It's a really great new technology.

Thank you for explaining that, because I've been kind of trying to wrap my head around how this vaccine has been different from vaccines in the past. We've been hearing a lot about herd immunity. It's my understanding that there are a couple of different ways to achieve herd immunity: there's the natural route, where we let it rip, and hospitals could be overwhelmed, more people could die. Or, we can achieve herd immunity through vaccination.

Right. You're absolutely right about that. Basically, what herd immunity does — or what it achieves — is, when you have a large proportion of a population who has protection against a particular disease — a virus or a bacteria — either because people have had that disease or because they've been vaccinated, that means the likelihood of that virus being able to infect anybody goes way down. So even when not everyone, for instance, in the population has protection themselves, personally, that herd immunity sort of serves to put a bit of a bubble around the whole population.

So our goal with COVID-19 is to be in a place where we have been able to achieve that herd immunity through vaccination. We know that people have some immunity following infection, but right now the estimate is that may only last 90 days. It's not long-term. So the goal is that we can use vaccination in the hopes that that immunity will be longer, and then also that we can avoid all of the severe consequences from COVID by having people vaccinated.

What proportion of the population has to be vaccinated for the vaccine to benefit the herd?

It varies for different diseases. For measles we like to say greater than 90%. As we've talked about COVID, we say that if we could get to 75% to 80% of the population vaccinated, that would be really wonderful. Our goal is to provide protection and then to get the circulating virus down so that we don't have as much virus circulating in the population.

For those who are nervous about the vaccine, are there precautions for that small segment of the population who wouldn't be able to be vaccinated? I'm not talking about personal belief, I'm just talking, like, physically.

Part of our goal in preparing health care providers to administer the vaccine was to provide education on situations where the vaccine would not be recommended. There are some specific things — like if you just received another vaccine, you need to wait for two weeks. If you're currently ill, you need to wait until you're feeling better to receive this vaccine. But then also, to look at: does someone have a history of prior allergic reaction to a vaccine, or does someone have a history of allergy to any of the vaccine components? Those are all things that will be evaluated as people come in to get vaccinated.

The other thing I should just point out is that the two vaccines have been licensed: Moderna for 18 and older and Pfizer for 16 and older. So right now we don't have a vaccine for children, so that clearly would be a situation in which vaccine could not be given.

I wonder if you could help clear up some other misconceptions about the vaccine. What are some of the concerns you're hearing from people that maybe could be easily cleared up?

Well, one of the things we're certainly hearing is, wow! This is great, but this vaccine came so quickly...is it really safe? Did it go through all the same safety checks that other vaccines go through? In fact, yes it did. There were a number of things that were done to speed up the process, to eliminate time gaps and things, but these two vaccines have gone through the same safety profile and trials that all the other vaccines you use and recognize have done.

Some of the things that were done to make the process more speedy were, one, there was this new technology that was available. There's always work being done on vaccine development, and so they were able to kind of have a jumpstart with that. Then when they went through all the clinical trials, they did all the clinical trials, but rather than waiting for one to finish before they started enrolling in the next, they enrolled all at once so they could be ready to go right away.

The other thing that was done is that the manufacturers started producing vaccine before they had approval. Normally they would never do that because of the financial risk, but the federal government said, we'll cover that. If your vaccine isn't approved and we have to waste all this vaccine, we'll cover that financial risk for you. So that meant the vaccine was ready right away.

Then the other thing that happened was that the FDA normally has a group of people that review these vaccine submissions, and it can take three to four months, because the team that does it is limited. They poured dozens of scientists onto the team so that they could do the same review in a shorter timeframe. So, there were a number of things like that that were done to really speed up the process but not compromise safety.

Can we talk a little bit about the timeline of getting people their shots? Certainly I know of people on the frontline getting their vaccines. What's the rollout timeline? I think a lot of listeners are wondering, when can I get it?

That's wonderful. We're both delighted that so many people want to get vaccinated right now, and then we're frustrated because we don't have enough vaccine. So knowing that the demand exceeds the supply initially, we've really focused on phases. So, you're right. We're really talking about getting health care workers vaccinated in this phase 1A, as well as residents of long-term care. Then when we move into phase 1B, the next phase, then we're looking at elders — so persons 75 and older — as well as some individuals who are doing frontline essential work. That's how the Advisory Committee on Immunization Practices has laid it out.

So as we move through these groups, we expect that we will have received enough vaccine in the state for that phase 1A by the end of January, and we'll be able to start moving into the second phase in February. So what I think of for myself — because I'm not in any special group at this point, I'm not in any priority group — I'm hoping that I'll get my vaccine by summer. So I think if people have that mindset, that certain priority groups will be getting vaccines initially and that for most of us, we'll be waiting until spring or summer...I think if we're thinking that way, it will really help.

One thing that's important to keep in mind is that as we get more people vaccinated in our population, even if it isn't me personally, it will still benefit us because it will be fewer people that could get or transmit COVID. So that's going to help a lot, but I think if we think in our minds that it's going to take us at least until spring to get through these various groups and then for the rest of us, summer will be the time when not only is the weather good, but vaccines should be in much more plentiful supply.

So what you're saying is, there is a light at the end of the tunnel here.

Oh, absolutely. One thing to keep in mind is that really a year ago, for those of us in epidemiology who are tracking these things, this was barely a blip on our radar a year ago...and we've already vaccinated tens of thousands of people in our state. Recognizing that obviously isn't our 5.6 million population, it's amazing what's been accomplished. Although this has been a year that we don't want to remember very much because it's been so tough, we're in a good place moving forward, and we are coming to the end of this. We just have to be patient and recognize that the end won't be at the end of January. It's going to be more like summer when everybody has the opportunity to be vaccinated.