More evidence emerges on why covid-19 is so much worse than the flu - The Washington Post

Researchers who examined the lungs of patients killed by covid-19 found evidence that it attacks the lining of blood vessels there, a critical difference from the lungs of people who died of the flu, according to a report published Thursday in the New England Journal of Medicine.

Critical parts of the lungs of patients infected by the novel coronavirus also suffered many microscopic blood clots and appeared to respond to the attack by growing tiny new blood vessels, the researchers reported.

They did not look at blood vessels in organs such as the kidneys and heart, where other researchers have described finding attacks from the virus and unexpected blood clots.

In larger blood vessels of the lungs, the number of blood clots was similar among covid-19 and flu patients, the researchers wrote.

They also found inflamed and damaged cells in the lining of blood vessels in the covid-19 patients.

Most surprising was evidence that the lungs of people attacked by the SARS-CoV-2 virus grew new blood vessels.

“The lungs from patients with covid-19 had significant new vessel growth,” a discovery the researchers described as “unexpected.” In an interview, Mentzer speculated that may have been an attempt by the lungs to pass more oxygen to hypoxic tissue.