Omicron is milder because it doesn't attack the lungs as strongly as other variants, according to the studies.
Omicron produced less damaging infections, often limited largely to the upper airway - the nose, throat, and windpipe - in testing conducted on mice and hamsters, The New York Times reports.
“The variant did much less harm to the lungs, where previous variants would often cause scarring and serious breathing difficulty," the report says.
The findings help to explain how, as cases skyrocketed, hospitalizations increased only modestly since Omicron was first reported in South Africa on Wednesday, Nov. 24 after the first sample of the strain formally known as B.1.1.529 came on Tuesday, Nov. 9.
"The level of Omicron in the noses of the hamsters was the same as in animals infected with an earlier form of the coronavirus," The New York Times report said. "But Omicron levels in the lungs were one-tenth or less of the level of other variants."
Still, something else makes Omicron different than other variants - its high level of transmissibility.
"Omicron is so highly transmissible at a level of transmissibility around the level potentially of measles, which is the most transmissible common virus agent we know," Connecticut native Dr. Peter Hotez, co-director of the Texas Children’s Hospital Center for Vaccine Development, told MSNBC in an interview last week.
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