New research reveals that COVID-19 attacks the lungs in a far different manner from the flu.
Unlike most respiratory diseases, significant impacts on blood vessels were seen in the lungs of seven COVID-19 patients. The lung tissue of those patients was compared to lung tissue from seven people who died of pneumonia caused by the flu.
There was evidence that COVID-19 attacks the lining of lung blood vessels and COVID-19 patients' lungs had many tiny blood clots and grew new blood vessels in response, according to the study published May 21 in the New England Journal of Medicine.
The findings support reports from doctors treating COVID-19 patients of widespread damage to lung blood vessels and the presence of blood clots that aren't typical in a respiratory disease, the Washington Post reported.
"What's different about COVID-19 is the lungs don't get stiff or injured or destroyed before there's hypoxia [oxygen deprivation]," study co-author Dr. Steven Mentzer, a professor of surgery at Harvard Medical School, told the newspaper.
"For whatever reason, there is a vascular phase" along with the damage more often linked with viral diseases such as the flu, he said.
The finding that the "lungs from patients with COVID-19 had significant new vessel growth" was "unexpected," the researchers added.
This may have been an attempt by the lungs to get more oxygen to oxygen-starved tissue, Mentzer told the Post.
"That may be one of the things that gets people better," he said.
Mentzer and his colleagues also tried to identify genetic or other factors that might help identify people who are most susceptible to severe COVID-19 illness, but weren't able to pinpoint any.
Certain groups of people have been hardest hit by COVID-19, including older patients, those with underlying diseases such as diabetes, and black Americans, the Post reported.
Other researchers have found similar damage and unexpected blood clots in other organs, such as the kidneys and heart, of COVID-19 patients, according to the newspaper.
The U.S. Centers for Disease Control and Prevention has more on COVID-19.