Doctors Answer 5 of the Biggest Questions About Immunity and COVID-19

Photo: Getty Images/Luis Alvarez
It's been nearly eight months to the day since the World Health Organization officially declared the COVID-19 outbreak to be an epidemic, yet there is still no end in sight to this disease in the U.S. On Monday alone, there were over 103,000 reported new cases across the country and 745 new deaths—a 64 percent increase in daily new cases from two weeks ago.

With such an exponential rise in outbreaks, it should come as no surprise that people are looking to anything—including immune-boosting products—to stay safe. According to Nutrition Business Journal, sales of immunity supplements are projected to increase by 51 percent in 2020 alone. But given that the novel coronavirus is barely a year old, there is a lot we don't understand about how COVID-19 works, including how to protect yourself from infection beyond wearing masks and maintaining social distance.

Experts In This Article

To that end, infectious disease immunologist with Allergy & Asthma Network Purvi Parikh, MD, and infectious disease specialist Rishi Desai, MD, say they are seeing some confusion when it comes to the immune system and COVID-19. Some of the precautions people are taking will not, in fact, protect them against coronavirus as they may think. The connection between immunity and COVID-19 is complicated, so here they set the record straight. The information they share could just be the most important news you read all winter.

Watch the video below to see a molecular biologist explain the second wave of COVID-19:

Will loading up on vitamin C and zinc will protect me from COVID-19?

Answer: Maybe—but there's not enough evidence yet. Both Dr. Parikh and Dr. Desai say that there is no robust scientific evidence showing that vitamin C or zinc can specifically help protect against COVID-19, but that doesn't mean you should pour your orange juice down the drain. "If you have a compromised immune system, you are more likely to catch any infection, including COVID-19," Dr. Parikh says. Essentially, consuming nutrients that help protect the immune system—like vitamin C and zinc—may indirectly offer protection against the virus.

"We shouldn't think of scientific evidence like a light switch or something that's either on or off," Dr. Desai says. "It's something that gradually builds until it gets to a point where [medical experts] feel comfortable saying there is a connection." Right now, existing evidence isn't strong enough yet for scientists to say there's a connection, which is why the National Institutes of Health (NIH) does not recommend either supplement for the purpose of preventing or treating COVID-19.

Slightly more promising, however, is the potential of vitamin D to protect against COVID-19. A small study of over 200 COVID-19 patients published in late October shows a potential link between vitamin D deficiency and COVID-19—although no causal relationship has been established, and more research is needed for this connection to be conclusive. While the NIH still doesn't explicitly recommend (or warn against) vitamin D supplementation to protect against COVID-19, both Dr. Desai and Dr. Parikh consider the link compelling enough to warrant taking precautionary measures. "This is really vital to know because most Americans are not getting enough vitamin D," Dr. Parikh says. (You want to aim to get between 400 and 800 IU or 10 to 20 micrograms a day.)

What about functional mushrooms—could they protect against COVID-19?

Answer: Maybe—but don't count on it. There has also been a growing interest in using immune-supporting functional mushrooms, such as reishi, chaga, and cordyceps, to help protect against COVID-19. While both doctors emphasize that there is no scientific evidence supporting this, Dr. Desai says to watch this space.

"Something like this has to be studied really rigorously, and we just don't have that level of rigor for functional mushrooms yet," Dr. Desai says. However, he says there's a lot medical doctors can learn from Traditional Chinese Medicine, which uses functional mushrooms more frequently. "For example, our main go-to medicine used to treat malaria [wormwood] is actually rooted in Traditional Chinese Medicine," he says. Still, both doctors emphasize that, as of now, the evidence that functional mushrooms can protect against COVID-19s is not there. (And be extremely skeptical of any products that explicitly claim to do so.)

I've been taking care of my health and immune system—so I don't have to take other COVID precautions, right?

Answer: False. Even if you load up on vitamins, head to bed early every night, and feel great, you are not invincible. "The biggest elephant in the room is exposure," Dr. Desai says. COVID-19 is spread through droplets generated when an infected person coughs, sneezes, or talks; there is growing evidence that it is airborne, too (meaning it can travel further distances through the air). The longer you're in a poorly-ventilated space with an infected person, the greater the risk that you'll contract COVID-19, regardless of how "healthy" you are. "Some people have the mentality of, 'my vitamin levels are great, I'm protected, so I'm going to head to that dinner party. But taking other precautions related to your immunity by no means mitigates the risk of exposure."

Dr. Desai says it really all comes down to basic math. "The goal is to minimize the amount of exposure to the virus you get," he says. "You can have the best vitamin levels in the world, but if you have enough exposure to the virus, your body will become overwhelmed." Take this as yet another reminder to continue wearing masks, maintaining physical distance when you're in public, and washing your hands properly.

Will going to get a flu shot put me at risk of contracting COVID-19?

Answer: Mostly false. Almost any trip outside the house can increase one's risk of contracting COVID-19 to some degree or another, depending on what you're doing, who you're with, and what precautions you're taking. But both doctors say getting your flu shot this year is vital to protecting your health. "Having the flu virus weakens your immune system, which can make you more susceptible to getting other illnesses like COVID-19," Dr. Desai says. "There's also the practical issue that if you do get the flu, then you're going to go into the hospital when your immune system is weaker, putting yourself at risk for picking up another virus while you're there."

Over-using hand sanitizer will make it less effective, right?

Answer: Mostly false. "There is some truth that if you overuse hand sanitizer that the chemicals in it may disrupt the good bacteria in your skin and gut, which work to protect us from [getting sick]. But it's a double-edged sword because it's really important to stay clean right now," Dr. Parikh says. Her advice: Hedge on the side of staying clean. "The [disruptions] occur after years and years of overuse and there's a deadly virus that we need to protect ourselves against now," she says.

Dr. Desai whole-heartedly agrees. "The only way I could see hand sanitizer being a problem right now is if you're applying it so much that your hands are becoming cracked with open sores, which can allow for harmful germs to get in," he says. Dr. Parikh adds that washing your hands with soap and water is gentler than hand sanitizer, so if hand sanitizer is irritating your hands, this is a better way to go.

As we work to navigate the latest wave of COVID-19, being armed with the facts is crucial. Moving through the winter season with this information in mind not only works to keep yourself safe, but it will help keep others safe, too. After all, we're in this together.

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