New studies on lab animals and human tissues show why Omicron variant causes “milder disease” than previous versions of the coronavirus.
- In studies on mice and hamsters, Omicron produced less damaging infections, often limited largely to the upper airway: the nose, throat, and windpipe, The New York Times reports.
- Scientists say the variant did much less harm to the lungs, where previous variants would often cause scarring and serious breathing difficulty, the Times also notes.
- “It’s fair to say that the idea of a disease that manifests itself primarily in the upper respiratory system is emerging,” said Roland Eils, a computational biologist at the Berlin Institute of Health.
- The Times points out how “[m]ore than half a dozen experiments made public in recent days all pointed to the same conclusion: Omicron is milder than Delta and other earlier versions of the virus.”
- Japanese and American scientists on Wednesday released a report on hamsters and mice infected with Covid-19. The study found those infected with Omicron had less lung damage, lost less weight, and were less likely to die. Scientists have been struck by results of milder symptoms in Syrian hamsters, a species known to get severely ill with all previous versions of the virus.
- The Times also pointed to work out of the University of Hong Kong, which studied bits of tissue taken from human airways during surgery. “In 12 lung samples, the researchers found that Omicron grew more slowly than Delta and other variants did,” reports the Times.
- Several other studies on mice and hamsters have reached the same conclusion, notes the Times.
- Covid-19 infections generally start in the nose or mouth, spreading down the throat.
- Mild infections like those from Omicron don’t spread much further than that.