Coronavirus and Your Immune System: How the Body Fights This Invader

As researchers around the world work feverishly to develop a vaccine and drug treatments, our own bodies’ immune systems are on the front lines in the fight against COVID-19. We rely on physical barriers like our skin and mucus membranes, as well as complex chemical and cellular barriers, to defend us against dangerous pathogens.

“Even cells that line our organs, like the cells that line your intestinal tract and respiratory tract, actually are part of the immune system too,” says Aileen Marty, M.D., professor, Infectious Diseases, at Florida International University’s Herbert Wertheim College of Medicine. “They produce chemicals and substances that contribute to getting rid of an invader. That’s true even of the cells that line our blood vessels. So, it’s a whole body approach when something enters our bodies in what the body then does to confront it.”

Dr. Marty addresses questions about the immune system in the latest episode of the Baptist HealthTalk podcast, hosted by Jonathan Fialkow, M.D., deputy medical director, chief of cardiology and a certified lipid specialist at Miami Cardiac & Vascular Institute.

Here are some Q&As from their discussion, which ranges from how the immune system works and strengthening it, to the differences in the immune responses between men and women. (Spoiler alert: the “man flu” is real!)

You can access this and other Baptist HealthTalk podcast episodes on your computer or smartphone, or via Apple Podcasts and Google Podcasts.

Dr. Fialkow: “Can you start with basically how our body protects itself from unfriendly invaders like a coronavirus?”

Dr. Marty:
“We have several layers of protection. We have physical barriers and we also have chemical barriers, and coupled with that, we have cells that are sentinel cells. They’re like watchdogs that are ready to see if something foreign enters our system and they react right away. They’re part of what we call the innate immune system. And a lot of the chemicals that these cells produce are some of the things that give us sickness behavior, make us feel ill. Once your more adaptive cells, cells that figure out what the actual invader looks like … your body starts to produce a specific molecule that targets a specific pathogen and reproduces potent antibodies.”

Dr. Fialkow: “Some people have the virus and are asymptomatic. Others may get aches and pains. Others may go on to pneumonia. Do we have any inkling as to what differentiates why some people may get a more variable response than others?”

Dr. Marty:
“Virtually every infectious agent causes multiple, different presentations in different people. It’s actually unusual for a particular germ to only cause X type of disease anytime it infects any human being. Having a variety of responses is completely normal. And some of it is biological differences; some of it is dependent on the dose of virus that somebody first encountered. Some of it has to do with what route the virus took to get in. Was it something that came into a mucosal surface? Did you eat it? Was it injected?

“All of these things alter how the body clinically manifests disease, or if you manifest disease at all. So, for example, if you get a very low bolus of infection the very first time, by a very small number of plaque forming units, your body has a better shot at figuring out how to control that virus — than if it gets overwhelmed with a huge bolus the first time that it encounters this virus.”

Dr. Fialkow: “We’re seeing more men with the disease than women, at least in the testing state. And we’re seeing more men with more virulent diseases. What can you tell us about that?”

Dr. Marty:
“Well, that’s actually fascinating, because we’ve known for a long time that ‘man flu’ is real. That actually, from not just the hormonal differences, but actually which genes are turned on and which are turned off in males and females. And I don’t just mean human males and females, I could be talking about heifers and bulls. It’s the same story. Sickness behavior is different by gender because there’s different levels of different chemicals that go up to higher degrees, and different cells go up to different degrees in males and females with certain diseases. And COVID-19 is one of those diseases that highlights that difference between men and women.”

Dr. Fialkow: “What would you tell the average listener who says, ‘Well, so my friend had it, are they immune? I’ve had it, am I immune?’ What are we seeing in terms of any protection from immune response? We know chicken pox, you get it, you don’t have to worry about chicken pox again. Yet, we need a flu vaccine every year because there are different influenza viruses. Can you speak a little bit about the concept of being immune if you’ve had COVID-19?

Dr. Marty:
“So that’s really interesting, and you picked some very interesting examples. Because chicken pox, for example, if you’ve had chicken pox, you never really lose that virus. And if you lose your immune maintenance of it, it’ll pop out as Shingles. Many pathogens actually do that. The reason that we maintain immunity is because the pathogen is still in us and every so often pokes its head out and our immune system slams it back down. And we’re still wondering whether that happens with this virus or not…The truth is, we only have, what, a little over four months of learning about this virus. So we’re trying to still tease that out. And right now, we’re doing serologic studies to determine whether people have immunity.”

Dr. Fialkow: “What are the kind of things that people can do at home to strengthen their immune system?”

Dr. Marty:
“Get off the couch. That’s the first thing.”

Dr. Fialkow: Yeah. I couldn’t agree more.

Dr. Marty:
“And the reason for that is very simple. It changes a whole bunch of different hormones in your body and it instructs certain cells that are lazily sitting around on top of your blood vessels to get out and go to work. Neutrophils become more functional, your endorphins and your enkephalins increase, which is good for your mood, which also reduces your stress. And the overall toning of your body is super, super important to ward off all kinds of infections.

“You want to have a multicolored meal, if at all possible. You do absolutely want to avoid fried foods, junk foods — that everybody’s aware of what those mean. You want, if at all possible, to have fresh vegetables … Absolutely do not add sugar to anything.”

Dr. Fialkow: “And then the last thing I think, which my listeners hear me bring up all the time, is sleep, which has restorative properties and has many significant boosts to our immune system.”

Dr. Marty:
“There are huge numbers of studies that show that lack of sleep, or improper sleep, increases weight gain, increases risk of diabetes, is overall bad for your heart — and it’s definitely bad for your immune system. So making sure that you get your rest is super important.”