The highly transmissible omicron variant of the coronavirus causes milder symptoms because it has a less severe impact on the upper respiratory system, according to new research.
A consortium of researchers from America and Japan released a study last month revealing omicron causes less damaging effects on the lungs, nose and throat. The study was conducted on mice and hamsters and is under review for publication in a Nature Portfolio journal.
In the study, researchers said omicron results in a “lower viral burden” in animals’ upper respiratory systems, making its viral load and replication in those tracts milder and thus less damaging.
The study demonstrates “attenuated lung disease in rodents, which parallels preliminary human clinical data,” researchers concluded.
The news follows data from South Africa, where omicron first emerged, showing the country had fewer hospitalizations and fewer deaths after a surge in confirmed coronavirus cases.
It also comes after a study last month published by the University of Hong Kong, which found omicron infects and multiplies 70 times faster than other variants but causes significantly less infection in the lungs.
Omicron has led to a historic spike in confirmed cases around the world and is overwhelming cities such as New York and Washington, D.C. The variant is more transmissible, the Centers for Disease Control and Prevention estimates, because it can evade past immunity from infection, vaccines and boosters.
“We have to reserve judgement that this is such a good thing that it might be less severe,” he said. “When you have so many cases it essentially obviates any diminution in severity because of the quantitative number of cases you will get with a highly transmissible variant such as omicron.”