Does A Vaccine Help You If You’ve Already Had COVID-19?

11:47 minutes

a nurse administering a vaccine to a woman, both wearing masks
Credit: Shutterstock

This story is part of Science Friday’s coverage on the novel coronavirus, the agent of the disease COVID-19. Listen to experts discuss the spread, outbreak response, and treatment.

Vaccines doses have started to rollout and are getting into the arms of people. We know that if you already had COVID-19, you build up antibodies against the virus. So do the vaccines affect you if you’ve already had COVID-19? 

Science writer Roxanne Khamsi talks about recent studies showing that a single dose of vaccine could boost immunity for former COVID-19 patients. She also discusses a study that found over 140,000 viral species in the human gut and Elizabeth Ann, the first cloned black-footed ferret.

Further Reading

Donate To Science Friday

Invest in quality science journalism by making a donation to Science Friday.


Segment Guests

Roxanne Khamsi

Roxanne Khamsi is a science writer based in Montreal, Quebec.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, a closer look at the power grid problems in Texas and a conversation with NASA’s senior climate advisor. But first, an FDA advisory panel is meeting today to consider whether to recommend approval of the Johnson & Johnson one-shot coronavirus vaccine. A decision would come over the weekend.

One question you hear over and over again from people about the COVID vaccines, do the vaccines work for you if you’ve already had COVID-19? There were recent studies looking at that question. And here to talk about it is Roxanne Khamsi, a science writer based out of Montreal who has been covering COVID-19. Welcome to Science Friday.

ROXANNE KHAMSI: Thank you, Ira. It’s great to be here.

IRA FLATOW: We know if you had COVID-19, you naturally build up antibodies. So what would a vaccine do for these people? I mean, what did these recent studies show?

ROXANNE KHAMSI: It’s a fascinating question. And essentially what the data is showing is, first of all, people who have had COVID should definitely get the vaccine, but that the second dose might not be as much of an essential as the first one. So if you’ve had COVID, your body’s already kind of revving up and built some lasting immunity against the SARS-CoV-2 virus.

But what the scientists have done is looked at the blood samples of people before and after they got their first shot. And they see that the first shot makes their antibodies increase by like a thousandfold, but that second shot doesn’t really make as much of an increase. And I can tell you more about the ways in which that first shot helps people that have had COVID already.

IRA FLATOW: Yeah, go ahead.

ROXANNE KHAMSI: So I kind like to think about this like your immune system is a little bit like the lottery. So there’s 10 to the 18 different possible antibodies that humans can make, which I think is a fascinatingly huge, huge number. So if you get sick with something like SARS-CoV-2, the COVID virus, your body is essentially trying its best to come up with the best immune response.

What a vaccine does, it’s almost like giving your body the winning lottery numbers to play because it’s really guiding your immune system to focus on specific parts of the virus that it can go after. So I think that’s a really important thing to understand is that even if you’ve gotten sick with COVID, the vaccine is going to help you out.

IRA FLATOW: So does getting sick from COVID do the same thing as getting the vaccine? I hear what you’re saying is no.

ROXANNE KHAMSI: It’s like, again, playing the lottery. If you’re getting sick with COVID the first time, your immune system’s doing its best shot by pulling the lever on that slot machine and saying, here’s the antibodies we can make now. But getting the vaccine is like getting a really targeted immune response. Because what the vaccine’s doing is it’s really showing your body that part of the virus that it can effectively go after.

IRA FLATOW: That explains it. Do we know how long immunity lasts? What can this tell us about your immunity?

ROXANNE KHAMSI: One of the things that scientists really want to know is how long are we protected against COVID if we get the vaccine? And what I’ve heard is scientists saying, it’s probably for at least a year, but we don’t know if it’s for five years or six years or how long. So that’s something that we’re going to have to study. And the hope, of course, is that it’s going to last for a really long time.

But it seems to be the scientists are saying we really shouldn’t necessarily bet on that 100%. We need to find out by doing these studies over a long period of time.

IRA FLATOW: Speaking of studies, there was a study out of Israel looking at the effectiveness of just one dose of the Pfizer vaccine. These were people who were not previously infected. What did that study show us?

ROXANNE KHAMSI: So this was a really informative study that came out of Israel. And it looked and it found that amongst these 9,000 health care workers who were eligible for a vaccine at the country’s largest hospital, they kind of tracked them over the course of a month. And they found that there was an 85% reduction in symptomatic infections with one shot of the Pfizer vaccine, which is huge, right? That’s amazing.

The caveat, of course, is that they only looked at symptomatic infections. So they didn’t track people’s infection in a more close way to see if there were maybe some asymptomatic infections going on. But I think it’s hugely hopeful. I also think it’s not reason to skip the second dose. But it gives us a really good feeling that we’re on the right track against this pandemic.

IRA FLATOW: We’re hearing a lot about COVID-19 variants. There are reports of a variant in New York City. What do we know about this? I mean, aren’t there always more variants coming out all the time?

ROXANNE KHAMSI: Yeah, and I think this is something so interesting that we’re really starting to appreciate about viruses. So if you’re infected with basically any virus, your body is going to start producing different variants as you get infected. If you have HIV, you’re in your initial infection phase, or polio, there’s going to be a bunch of different variants that are being spewed out of cells during that initial infection. But what we’re finding now as we’re doing so much sequencing with COVID-19 is that the virus that causes COVID definitely generates variants.

And we have to figure out what are we call variants of concern. And, as you alluded to, in New York, there have now been reports of a particular variant known as B1526. And scientists have seen that it kind of cropped up in November. And now it appears to account for one out of every four cases in the city.

IRA FLATOW: Let’s move on to your next story. We talk about the microbiome a lot around here on Science Friday because it’s my favorite subject, the bacteria in our gut. And researchers, I understand, are looking at the viruses in our gut, the bacteriophages, as they call them, right? What are they finding out?

ROXANNE KHAMSI: Yeah, so this is really interesting. Because here we are so focused on one virus this whole past year, but we are what I think of as walking human Petri dishes. And I love the microbiome too. I think that it is a fascinating thing to think about. And so bacteriophages, as you’re kind of mentioning, are these viruses that infect bacteria.

What scientists have done is they analyzed more than 28,000 different gut samples from people and 3,000 samples of bacteria within individuals. And they found more than 140,000 different viruses that are bacteriophages, as you mentioned, that infect the bacteria in our gut. So half of those were ones that they’ve never even known about before, which is just, I think, amazing.

IRA FLATOW: It is amazing. It shows you how much– wherever you have a bacterium, you’re going to have a virus or more.

ROXANNE KHAMSI: Exactly. And these are healthy people, right? So this isn’t like– we shouldn’t be scared of the fact that we have viruses in our gut that live with us. It’s just like with the microbiome. 10, 15 years ago, the idea that we were walking hosts to bacteria in our gut seemed kind of maybe scary to some people, but we got really comfortable with the idea. And now it’s the same, I think, with viruses. I think it’s great.

IRA FLATOW: Your next story looks at devastating fires in the Amazon rainforest in the last few years. We’ve known about fires in the Amazon for many years. What makes this story different?

ROXANNE KHAMSI: As you mentioned, we definitely have been hearing about worsening fires in the Amazon. In 2019, there were so many headlines about, is it the worst year for forest fires in the Amazon? But kind of what might have gone a little bit under the radar is that 2020 was actually worse. So NASA found this out by using satellite data, and they found that there were 1.1 million hotspots in 2019. But that increased to 1.4 million in 2020.

And so that’s like a 23% increase from 2019 to 2020. And it’s hugely concerning, because as you know, the Amazon is the lungs of the planet.

IRA FLATOW: Yeah. And people are starting these fires, right? We’re not talking about lightning, things like that.

ROXANNE KHAMSI: Absolutely, that’s a great point. A lot of these forest fires are set by people to clear land for farming or for cattle. And so it’s really a human-driven phenomenon, to a large extent. And the Amazon is a wet climate. But what’s happening is that last year was a little bit drier, so some of these humans-set fires lasted longer, did more damage.

IRA FLATOW: And as you say, you talk about the Amazon as the lungs of the Earth. It’s important to have the Amazon healthy, like having your lungs healthy.

ROXANNE KHAMSI: Absolutely. And you know, Ira, the thing is that we’re watching the health of the Amazon decline a little bit, which is of concern because by scientific study, we’ve seen that its job or its role in the environment is to capture carbon. That’s why we call it the lungs of the planet because it takes some of that global warming carbon dioxide out of our global system.

But since the 1990s, it’s taking about a third less carbon from the air. So that’s something that scientists are really concerned about.

IRA FLATOW: Finally, we need to talk about Elizabeth Ann, which Elizabeth Ann is blowing up all over the internet. For people who are not paying attention, tell us who or what Elizabeth Ann is.

ROXANNE KHAMSI: Elizabeth Ann is the cutest thing that has happened to us in a really long time. So Elizabeth Ann is the first cloned black-footed ferret. And she’s also the first cloned native endangered species in North America. So she is just this adorable little ferret who was born via c-section on December 10. And scientists announced that she had been born this past month. So everyone’s really excited because there’s a potential that she could help revive this endangered species, and the fact that she’s cute does not hurt.

IRA FLATOW: And where did all of this happen?

ROXANNE KHAMSI: So this happened in the US. But what happened was that we’ve thought that the black-footed ferret was gone, was extinct. And then in the early 1980s, there was a farmer who found some of these on his land. And what scientists did back then is they sent a sample of one of those ferrets, named Willow, to the San Diego Zoo. Because Willa was not able to breed successfully, but they thought that she might have something to hold for the future.

So here we have these frozen samples at the zoo for decades, and her genetic material was taken, and they created an embryo and put it in one of the ferrets that has survived from the seven that lasted on that farm. They were able to get a surrogate to produce Elizabeth Ann.

IRA FLATOW: Do you think they’re going to do this a few more times to help revive the species?

ROXANNE KHAMSI: Absolutely. She’s got sisters on the way coming, and they’re hoping to breed her with some of the other clones they’ve made. And to reintroduce some of that really vital genetic diversity into the population of black-footed ferrets that have been sustained from only the seven individuals that were able to breed that were found on that farm.

IRA FLATOW: So it’s good news for reviving other animals.

ROXANNE KHAMSI: It’s fantastic. I think it’s a little bit Jurassic Park seeming, but I think it’s also just great, great news. It’s cute. It’s hopeful. I think that it puts a smile on my face when I think about it.

IRA FLATOW: Well, we could all use that these days, right?


IRA FLATOW: Thank you, Roxanne. Roxanne Khamsi is a science writer based out of Montreal.

Copyright © 2022 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of Science Friday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies/

Meet the Producers and Host

About Alexa Lim

Alexa Lim was a senior producer for Science Friday. Her favorite stories involve space, sound, and strange animal discoveries.

About Ira Flatow

Ira Flatow is the host and executive producer of Science FridayHis green thumb has revived many an office plant at death’s door.

Explore More