New studies reinforce belief that Omicron is less likely to damage lungs
Six research groups’ findings all suggest variant multiplies more in throats and causes less serious disease
A growing body of evidence indicates that the Omicron Covid variant is more likely to infect the throat than the lungs, which scientists believe may explain why it appears to be more infectious but less deadly than other versions of the virus. Six studies – four published since Christmas Eve – have found that Omicron does not damage people’s lungs as much as the Delta and other previous variants of Covid. The studies have yet to be peer-reviewed by other scientists.
“The result of all the mutations that make Omicron different from previous variants is that it may have altered its ability to infect different sorts of cells,” said Deenan Pillay, professor of virology at University College London.
“In essence, it looks to be more able to infect the upper respiratory tract – cells in the throat. So it would multiply in cells there more readily than in cells deep in the lung. This is really preliminary but the studies point in the same direction.” If the virus produces more cells in the throat, that makes it more transmissible, which would help to explain the rapid spread of Omicron. A virus that is good at infecting lung tissue, on the other hand, will be potentially more dangerous but less transmissible.
Researchers from the University of Liverpool’s Molecular Virology Research Group published a pre-print on Boxing Day that shows Omicron leading to “less severe disease” in mice, according to Prof James Stewart. The paper showed that mice infected with Omicron lose less weight, have lower viral loads and experience less- severe pneumonia.