Today, he gets an inhaled steroid every day, two puffs in the morning and two at night. He breathes deeply 20 times. He rinses his mouth. “Some sharks die if they stop swimming,” he will say. He likes to talk about sharks and their strong, boneless bodies. “They never get sick. They’re immune to fevers!” I fill his humidifier with cold water. I set the emergency inhaler by his bed.

Although most people will not remember, three years ago, in late winter, another virus was scaring parents in my community. Unlike this coronavirus, which appears to be most severe in older people, respiratory syncytial virus, or R.S.V., is responsible for around 57,000 hospitalizations of young children in the United States every year. Many of them will have asthma. Even though parents at my son’s preschool talked about the seasonal spike in infections at the time, the risk of R.S.V., seemed far away. Or something only happening to children who were born premature.

Then a bad cold hit. My 2-year-old son had a fever of 103.8 and rapid breathing I’d never seen. I wrapped him in a blanket and rushed him to the hospital, where we learned he had R.S.V. His blood oxygen level was at 76 percent on admittance. It should be close to 100 percent and any level lower than 95 percent is cause for concern. It took hours to get him stable, and four days in the intensive care unit before we could take him home.

The shock of that experience makes the threat of this new virus feel uncomfortably close. But the Centers for Disease Control and Prevention has said the new coronavirus, which causes the disease Covid-19, is so far not infecting children as frequently or severely as adults. No one yet seems to know why, and that’s partly because the virus, which originated in China, is so new. “Most of the information we’re getting is from China,” said Dr. Sharon A. McGrath-Morrow, M.D., a professor of pediatrics at Johns Hopkins University. “But it looks like generally children have been spared the more severe manifestations of this virus.”

For me — and, I imagine, for many parents of the approximately six million other children in the United States who have asthma — it’s hard to believe that this coronavirus, which targets lung cells, isn’t more dangerous to our kids. So I called Dr. Gwynne Church, M.D., a pediatric pulmonologist at University of California, San Francisco, Benioff Children’s Hospital. She admitted that almost all the research on the new coronavirus so far has been focused on what is leading to severe pneumonia and death, not its effect on common chronic diseases. “It’s reassuring that asthma was not a risk for death with the coronavirus in China,” she said. “But we don’t know that the virus wasn’t leading to sickness causing increased asthma.” It’s an evolving situation, she added, and our populations are not identical. For one thing, the reported rate for childhood asthma in China is lower than in the United States.