As I grew older, I've noticed that we all cling to these metaphors of physical violence when talking about the immune system. Immune cells called phagocytes devour trespassing bacteria. "Killer" T-cells destroy cells that have been hijacked by viruses. It's ingrained in how we explain the complex system within ourselves that protects us from foreign invaders.

When I got sick as a kid, my father would draw a cartoon of the battle my immune system was fighting in my body. He would sketch an antibody man, shaped like the letter Y, with bulging muscular arms, getting ready to beat up an angry-faced bacteria or virus.

I've found myself thinking about the immune system and cytokine storms, and about the upset balance between overreaction and underreaction, as we observe government and individual missteps in reaction to the pandemic. We could stand to learn some lessons from our own immune systems—about how we mount a defense, decide when to act and when to lay low, and how we define ourselves versus what's "foreign."

“It’s all about balance and timing,” Brodin said. “The immune system is an exquisitely well-balanced system. But if someone has an allergic reaction, they can be dead in half a minute or seconds. What does that tell you? It tells you the immense power that the immune system has. It can kill you within seconds, but it usually doesn’t because it’s well-regulated.”

If the immune system killed everything foreign in sight, we would not have a microbiome (the millions of beneficial bacteria that live in and on us), and our bodies would resemble "scorched earth," said writer and journalist Matt Richtel, the author of An Elegant Defense: The Extraordinary New Science of the Immune System.

A healthy immune system is not fighting every minute. It's also deciding what not to react to, what not to kill; this discernment is a skill it spends our whole lives refining. The immune system's job, said Petter Brodin, an immunologist at the Karolinska Institute in Sweden, is to maintain a healthy relationship with all of the bugs that live in, on, and around us.

A timely illustration of this is one of the leading causes of death among people with COVID-19, the illness caused by the new coronavirus. It's an extreme overreaction of the immune system, called a cytokine storm . This storm is a thunderous, devastating, often fatal burst of immune overactivity. In these cases, it is not the virus that directly kills a person, but their immune system. There is discussion among clinicians about a treatment for COVID-19 patients that wouldn't "boost" the immune system but instead, turn it down.

But this conception of the immune system isn't entirely correct. It does protect us from invading cells, but the system at large is not a cannon set on autopilot. What's more important to the immune system than all-out war is balance. An immune system that is overly-"boosted" is not desirable, but in fact, deadly.

Simultaneously, my inbox is teeming with pitches for products that claim they can "boost" my immune system. As a novel coronavirus infects hundreds of thousands of people all over the world, these ads prey on the desire to bolster our troops, give them more ammunition—to go to war. Supplements, juices, soups, elixirs, broths: they all promise to get my immune system into fighting shape for its inevitable showdown with a new enemy.

“The imagery of war is hard to get away from,” Turney wrote. Earlier this month, New York's governor, Andrew Cuomo, said of the COVID-19 pandemic, "This is a war. We have to treat it like a war."

In a 2016 essay in Aeon about the militaristic language we use for the immune system, science writer Jon Turney described a children's book from the 90s called Cell Wars, about "a brave band of cells that keep you healthy by constantly battling against all kinds of invading germs. Every minute, every hour, every day of your life, they are fighting.”

The immune system is complicated. It employs a vast network of cells and tissues to continuously scan the body for trouble. We are born with innate immunity, which is our body’s ability to fend off invading cells from the get go. And throughout our lives, our body’s learned immune response, the adaptive immune system, steps in. Each time we get an infection or a vaccination, our immune system learns, and can protect us from that pathogen if we encounter it again.

To do this, the body recognizes things that don’t belong, called antigens. Antigens are proteins on the surfaces of bacteria, fungi, or viruses. A longstanding conception of the immune system is that its job—summarized in just a few words—is to detect cells that are not "us."

In the 1949 book, The Production of Antibodies, scientists Frank MacFarlane Burnet and Frank Fenner introduced this notion that the "self" was inextricably tied to the immune system. Burnet thought that the self was actually defined by the immune system, since it decided what the "non-self" was that needed to be attacked. Just like there are borders around countries that define its residents, our body was the border that contained our cells. Any other "not-self" cells that crossed those borders needed to be killed.

We know now that it's more nuanced than this. All around us, every day, microbes lurk. They’re on our bodies, computers, clothes, food, and, yes, doorknobs. Any one of them could be your body’s foe. But many of them are also your body's friends. Others are microbes that care little about you at all.

With the discovery of the microbiome, we've come to realize that our immune system frequently leaves the microbes in our bodies alone, even though they are not human cells, technically are not the “self.” At other times, the immune system even persuades them to colonize us. Take one antibody protein called IgA, for example, after it recognizes the antigens on some gut bacteria. "Does that signal their destruction?" Turney wrote in the Aeon essay. "No." Instead, when IgA binds to the bacteria, it helps it take root in our guts, establishing a new home there.

Cytokine storms are one example of how too much immune reactivity isn't ideal. When the novel coronavirus enters the body, the immune system senses it. It releases inflammatory cells, called cytokines, which enlist other immune cells to help. This process should be controlled and regulated, but in some patients with COVID-19, it starts to boil over: The lungs are flooded with immune cells trying to fight the virus and clear away damage. But they start to build up, kill healthy tissues, and damage other organs. It leads to an inability to breathe as fluid floods the lungs, drowning a person on dry land, while their organs fail.

Getting your immune system to hulk out on turmeric or vitamin C—even if that did work—isn’t the desired end goal.

Immune imbalance can lead to other problems, too: autoimmune disorders, when the body attacks cells that it’s not meant to, or food allergies, when the immune system reacts too strongly to a foreign substance. This is why the notion of “immune boosting” doesn’t make sense, Richtel said. Getting your immune system to hulk out on turmeric or vitamin C—even if that did work—isn’t the desired end goal.