Is there any research showing yogurt, dogs or super immunity protects from Covid?

HOST: As of about an hour ago, there have been 1.6 million cases of COVID in Minnesota. More than 12,000 Minnesotans have died from the disease. And yet, there are still folks out there, maybe you're one, who have never had COVID. Now we've all been told by the experts that masking, distancing, and vaccinations are key to avoiding the virus.

And still, there are those who follow all the rules and get COVID, and those who don't follow any of the rules and don't get COVID. It's leading many of you to wonder if there's something else at play. Well, we asked listeners to weigh in on their theories on how they've been able to dodge COVID. And we've got several answers. Here's NPR listener Therese Melhem.

THERESE MELHEM: I think I am super immune. I work in a hospital, and any time I've had symptoms over the past two years, I test. Even early in the pandemic, I was able to test, leading me to believe that I didn't have it then either. This May, my partner got it and because I'm a relatively healthy person, I continued to sleep in the same bed as him. I continued to test negative despite consistent contact.

It was at this point that I decided to try and research super immunity. There was nobody within a close distance that was looking into it. But I did attempt to contact someone at UMN.

HOST: Is there such a thing as being super immune? Well, here to answer that question and others is Dr. Priya Sampathkumar. She's an infectious disease specialist with Mayo Clinic. Welcome, doctor. Well, let's see. We thought we had the doctor with us. We hope that she's there somewhere. Terribly sorry about this. This has happened now every day this week with some technical problems that we seem to have in the system here.

If you are tuning in, we are attempting to talk to a Mayo Clinic specialist about those who have managed to avoid contracting COVID over the past two to three years and how they managed to do that. There is no shortage of theories as to why there are some people who have remained COVID-free. Do we have the doctor? We don't have the doctor.

PRIYA SAMPATHKUMAR: I am back.

HOST: We do have the doctor. There you are. So nice to have you here, Dr. Sampathkumar. How are you doing?

PRIYA SAMPATHKUMAR: Good.

HOST: Excellent.

PRIYA SAMPATHKUMAR: I'm sorry I dropped off accidentally for a minute.

HOST: Oh, you know, this is just how it happens. It's live radio. Say, I don't know if you had the opportunity before you dropped off to hear our listener who was talking about having super immunity. Is there any research into natural immunity, natural super-- so-called super immunity?

PRIYA SAMPATHKUMAR: So some people are trying to look into it. It's still not clear if that is really a thing. So the caller, what I heard was she's had lots of exposure to COVID but hasn't had COVID, including exposure to her partner at home. She stayed in the same room with that person and didn't get COVID. So there are a few possibilities. One is that she did get COVID. It was asymptomatic. She never manifested any symptoms.

That could be one possibility. She did say she had tested multiple times, and each time she tested, she was negative. But it could be she had so little virus the test wasn't good enough to pick it out. The other possibility is that she truly never got COVID. Now people often ask, are there ways other than the PCR test or the antigen test to know if you've had COVID in the past?

And one thing you can do is to get an antibody test to see if you've previously had COVID and developed antibodies as a result of that. There's a specific type of antibody that needs to be checked for, so the vaccination itself can give you what are called spike antibodies. And infection gives you, in addition to the spike antibodies, another one called the nucleocapsid. So a blood test could be done.

I do want to caution that the test isn't completely 100% predictive of past infection. So if you have those antibodies, then you can be very sure you've had infection in the past. But if you don't have antibodies, it doesn't always mean you haven't had an infection in the past. It could just mean your levels are so low it's not detectable.

HOST: Interesting. All right, we're going to listen to another COVID dodger.

STEPH ASH: Hi, this is Steph Ash in St. Peter, Minnesota. And to the best of my knowledge, I have not yet contracted COVID. I don't really know why. Between us, my husband and I have three college-age kids who have come in and out of our home during the whole time. Plus we both work at colleges among young people who aren't exactly known for COVID-safe behaviors. And we've had several first contact exposures.

And we've even put kids up in offsite locations to keep them away from us. But so far, I have completely avoided it. My theory, I mask in most public shopping places. I minimize dining out, especially during the worst of COVID. I work in a flexible office space with flexible office hours. Plus my college had incredible COVID tracing and testing available. I eat a lot of yogurt. A dog sleeps in my bed. I don't know. But fingers crossed that it continues.

[LAUGHS]

HOST: OK, yogurt and sleeping with dogs, I think that might be a bit of a joke. But you're hearing this kind of thing, doctor, from patients or the public, just, again, a lot of exposure. To the best of her knowledge, she's not gotten COVID.

PRIYA SAMPATHKUMAR: Yes, and what this person said makes perfect sense. She is being careful, although she has potential for a lot of exposure. She is masking in public places. She's avoiding outdoor dining when your mask comes off. So even though she's around a lot of young people, I think it is a reasonable assumption that she's actually never had COVID.

And I don't think there's any research on yogurt. I mean, being healthy, in general, will help you. But there are no specific multivitamin supplements or health food supplements that seem to make a difference in your risk of acquiring COVID. The sleeping with the dog, though, I think may be helping.

HOST: What?

PRIYA SAMPATHKUMAR: My husband will disagree. No, I'm just kidding.

HOST: OK.

[LAUGHTER]

I was thinking, really? I hadn't heard that one before.

PRIYA SAMPATHKUMAR: No.

HOST: Oh, but-- so masking, in your estimation, has been one of the things that this woman has done that has been most helpful.

PRIYA SAMPATHKUMAR: Yes. I think that there's been so much controversy around masking. But I think it's the single thing that definitely helps. And whether you use an N95 mask or a regular mask, I think all of them protect you to different degrees. And I think a mask that you wear consistently is the best thing for you.

HOST: OK. Do we know how many people have had symptomatic cases of COVID, by the way?

PRIYA SAMPATHKUMAR: In terms of how many of all the cases, how many are symptomatic?

HOST: Yes. Do we know?

PRIYA SAMPATHKUMAR: So it varies. Probably 80% of people have symptomatic COVID. Somewhere between 10% and 20% have asymptomatic COVID. And your subsequent episodes, so there are many people in the US who have had COVID more than once, and it seems like the subsequent episodes generally tend to be milder and are more likely to be asymptomatic.

HOST: So this is the beginning of August. Of course, schools are around the corner and elementary, college. What are the predictions of a fall wave of COVID infections?

PRIYA SAMPATHKUMAR: So the one thing that COVID has taught us is that almost all predictions don't come true. So I'm hesitant to make any predictions. But with the vaccination rate in the US, the availability of vaccines for young children, I'm hopeful that as more and more vulnerable people get vaccinated that the next wave of COVID will not be as severe that they'll be fewer cases, and they will continue to be milder cases.

But any time you get people together in enclosed spaces, the risk of COVID does go up. And we have some tools we've learned a lot in the last two years. So keeping an eye on case counts and taking extra precautions when cases go up, wearing masks when cases go up in your community, getting vaccinated, including booster doses of vaccine when indicated, and continue to work on improving air quality in indoor spaces I think will be the way to keep us safer going forward.

HOST: All right, Dr. Sampathkumar, it's been a pleasure. Thank you so very much.

PRIYA SAMPATHKUMAR: All right. Thank you.

HOST: Dr. Priya Sampathkumar is an infectious disease specialist at Mayo Clinic.