This May Be Why Coronavirus Severely Sickens Some and Not Others

Stanford University scientists say severely ill coronavirus patients have slow immune systems.

One of the most confounding questions about the deadly coronavirus is why some patients have mild or no symptoms and others are laid low by it. Scientists at Stanford University say it appears one reason folks are hard hit is because their "first responder" immune cells, which should immediately attack viruses and bacteria, instead limp along to combat foreign invaders.

Researchers at the college's medical school, and other institutions, have turned up immunological deviations and lapses that appear to spell the difference between severe and mild cases of COVID-19.

“These findings reveal how the immune system goes awry during coronavirus infections, leading to severe disease, and point to potential therapeutic targets,” said Bali Pulendran, professor of pathology and of microbiology and immunology and senior author of the study published this week in Science magazine.

Scientists also found elevated levels of bacterial debris, such as bacterial DNA and cell-wall materials, in the blood of those COVID-19 patients with severe cases. The more debris, the sicker the patient.

“One of the great mysteries of COVID-19 infections has been that some people develop severe disease, while others seem to recover quickly,” Pulendran said. “Now we have some insights into why that happens.”