If schools reopen, how many kids won’t?

Dr. Wachtell is a research associate professor of American studies at Yeshiva University.

An electron microscope image of the new coronavirus, which has been linked to multisystem inflammatory syndrome in children.Credit…NIAID-RML, via Associated Press

My 20-year-old son is a strapping 6-foot-2-inch, 190-pound man, with a permanent five o’clock shadow, palms callused from fitness training and hair on his chest. Not surprisingly, he did not fit on the small bed in the pediatric emergency room.

But that was the least of our worries as his blood pressure dropped and his blood levels of troponin and B.N.P., biomarkers associated with heart attacks, rose. When his doctor explained he might need a drug to help his heart contract, I thought I might faint.

It was a Friday night, two weeks ago, and he was suffering from what doctors are calling multisystem inflammatory syndrome in children, a rare but growing condition linked to Covid-19. But he is no child, and the illness was so new it did not yet have an official name.

The first doctors to examine him, at an urgent-care clinic in Manhattan, thought he simply had inflamed tonsils and maybe an abscess. He was prescribed antibiotics and steroids, and told to return if he did not feel better in 48 hours.

Parenting during the pandemic is challenging in many respects, yet the one mercy seemed to be that children, and even young adults, were far less severely affected by the virus. The arrival of MIS-C changes that.

As we contemplate such decisions as reopening schools, we must factor in the new risk of MIS-C. Our children — whether in kindergarten or college — are in far more danger than we realized. On May 7, the same day my son was hospitalized, a 5-year-old boy died in a nearby hospital, becoming the United States’ first known victim of the syndrome. How many others will there be?

MIS-C is thought to be a delayed overreaction of the immune system to Covid-19 that can cause a deadly heart inflammation and a kind of toxic shock.

Doctors have identified a range of symptoms. The most common is a fever. Others can include rashes, abdominal pain, diarrhea, vomiting, swollen glands, swollen hands or feet, bloodshot eyes, a strawberry-colored tongue and red, cracked lips. My son’s case began with swollen glands and soon progressed to a high fever.

At first, I believed the inflamed tonsils diagnosis. Luckily, though, New York State released a health advisory about the syndrome. That night, while threshing my email inbox, I stumbled upon it. Call it a mother’s instinct, or call it neurotic, but I felt fairly certain he had this rare pediatric illness. When he awoke the next morning with a rash, that was the clincher.

But how did my son end up with a deadly syndrome as yet unmapped and unnamed?

He had an extremely mild case of Covid-19 in March, while in quarantine with college friends, and in April he tested positive for antibodies. We thought that was the end of it. We considered him the lucky one, the one with presumed immunity.

Instead, his immune system went into overdrive. Eight weeks after he was exposed to someone with Covid-19, he was hospitalized. During his first day in the hospital, we received a steady stream of reassuring news. Then on the second evening, his blood pressure suddenly began to drop.

I am a professor of American studies and recently spent several years researching the life of Ellen N. La Motte, a long-forgotten nurse and public health crusader. In particular, I focused on her war writing. Soon after World War I began, she volunteered as a nurse in a French field hospital; later she published an explosive book of stories, “The Backwash of War,” about the experience. I spent endless hours immersed in those deeply unsettling and darkly humorous tales of wounded and sick hospitalized soldiers.

However, the influenza pandemic of 1918-19 far outstripped World War I in its lethality, killing more than 50 million people worldwide; it was especially deadly among young adults.

In October 1918, when the pandemic struck New York City — killing my paternal grandmother’s fiancé, a pharmacist — La Motte volunteered again. She later recalled: “I went to work in an influenza hospital during the height of the epidemic. Got it myself after that and was pretty sick for about a month.”

My son was very fortunate. He received amazing care from La Motte’s modern-day heirs. His blood pressure stabilized, and after four nights in the hospital, he returned home. “His immune system is functioning beautifully,” his doctor reported in our final call. “And if he never saw a cardiologist again, he would be just fine.”

His is a story with a happy ending, but it must also be read as a cautionary tale.

I desperately want to return to campus in the fall. I also desperately want my two sons to return to their college campuses and my six younger nieces and nephews, ages 4 to 15, to return to their schools.

But I think of my grandmother, at the age of 18, losing her fiancé. I think of all the young men, so like my son, who died in the influenza pandemic, despite the help of nurses like La Motte. I think of what might have happened if my son had delayed going to the hospital.

It is already well recognized that if schools reopen, they could become vectors of disease, with students infecting older family members. After all, 7-year-olds do not live alone. And research shows that children, even though they may be asymptomatic, are infected at the same rate as adults.

Now there is a new risk with which to reckon. When my son left the hospital on May 11, there were 38 confirmed cases in New York City. Eight days later there were 147.

New York City’s public schools, with over one million students, have perennially overcrowded classrooms. And even the most elite colleges have communal bathrooms. These problems are daunting and the dangers deadly real.

Unfortunately, the equation of MIS-C is starkly simple. The more children who are infected in schools or elsewhere, the more children who will develop the syndrome and be rushed to the emergency room. Sadly, many will arrive far sicker than my son.

Cynthia Wachtell (@cynthiawachtell) is a research associate professor of American studies at Yeshiva University, where she directs the S. Daniel Abraham Honors Program. She is also the editor of “The Backwash of War: An Extraordinary American Nurse in World War I.”

The Times is committed to publishing a diversity of letters to the editor. We’d like to hear what you think about this or any of our articles. Here are some tips. And here’s our email: letters@nytimes.com.

Follow The New York Times Opinion section on Facebook, Twitter (@NYTopinion) and Instagram.