Why do some people die but others recover from virus?

This week, the state of Washington reported two new coronavirus cases. One is resting at home, recovering nicely. The other is dead.

Why do some people fare so much worse than others?

Here’s a clue: The recovering patient is a high school student, while the dead man was in high late 50s and “medically highrisk,” according to authorities.

“People who have the most severe impact of disease are older and medically fragile, with underlying medical conditions,” according to Dr. Nancy Messonnier, Director of the Center for the National Center for Immunization and Respiratory Diseases. “That is consistent with what we generally see with other viral respiratory infections.”

“Many of the cases are recovered or recovering,” she said.

Emerging research supports the U.S. trend.

For people who are otherwise healthy, fewer than 1 percent died. The death rate jumped to 5.6 percent for those with cancer, 6 percent for hypertension, 6.3 percent for chronic respiratory disease, 7.3 percent for diabetes and 10.5 percent for people with cardiovascular disease.

The overall death rate was 2.3 percent. That likely an overestimate because people with mild cases may not have sought medical help, so weren’t included. But it’s still high, rivaling the 1918 flu pandemic.

Children under the age of 9 didn’t die. But for patients between the ages of 70 and 79, the death rate was 8 percent. For those over the age of 80, it was 14.8 percent.

If the death rates hold true in the United States, that means if you have 300 friends, six of them would likely die, on average. If your friends are under the age of 50, you might lose just one. But if they’re over 70, you’d lose more than 24.

The analysis comes from the largest patient-based study of the illnesses from the new virus, published in the prestigious Journal of the American Medical Association. It’s based on study of 72,314 people.

The pattern is consistent with other coronaviruses like SARS and MERS, which disproportionately killed the older and sicker.

But it differs from flu outbreaks. The annual flu usually kills young children and the elderly. The 1918 flu pandemic, in contrast, was most deadly for people between the ages of 20 to 40.

To be sure, young and healthy people can also die from the disease — such as Li Wenliang, a 34-year-old doctor widely regarded as a hero in China for blowing the whistle on the threat posed by the disease, then targeted by police. Perhaps, while treating patients, he was exposed to a large blast of the virus.

Why are older and sicker people more vulnerable? No one knows for sure. But research on other respiratory viruses offers some hints.

Some people — especially the elderly and the sick — may have an immune response that is dangerous, said Dr. Melanie Ott of the Gladstone Institute of Virology and Immunology and a professor at UC San Francisco’s Department of Medicine.

It’s called a “cytokine storm,” when immune cells are overproduced and flood into the lungs, causing pneumonia, inflammation and shortness of breath.

“The indication is that there is very specific cytokine induction in different cell types and there is a ‘cytokine storm,’ causing a sepsis type of deterioration,” she said.

But fatal illness may also be caused by direct damage to the lungs.

If the airways of the lungs are already damaged or compromised — from smoking and other ailments — then a person is much more susceptible to a pathogen that enters and infects the injured tissue. Also, people with lung disease already suffer from reduced breathing, said Dr. Jack Coleman, senior medical director of the Lung Health Institute in Tampa, Florida.

“We don’t understand the lung pathogenesis,” said UC San Francisco virologist Dr. Charles Chiu.

“So these fundamental questions really need to be studied,” he said. To learn what makes the virus so deadly, we need cell cultures, “organoid” models and perhaps animal research.

“Ultimately, will will need to do the basic science to really understand it,” he said, “and to be able to develop targeted therapies that would be effective.”