COVID-19 | Ómicron causes less serious disease than Delta, study finds

The Omicron variant of SARS-Cov-2 causes less severe disease than Delta, a study suggests with mice, which experienced less weight loss, less viral load and less severe pneumonia.

The study, which has been published in the biorXiv repository, in which the texts have not been subjected to review by other experts, analyzed caused by Ómicron in comparison with the Delta and Pango B lineages in tests with modified mouse models.

No animal model can predict “with absolute certainty” the consequences of infection in humans, but the results “strongly suggest” that the clinical consequences of infection in humans by Omicron

In addition, they point out that Ómicron can lead to a less severe and / or faster recovery from clinical disease, which is reflected in

However, due to the high transmissibility as it could evade “Much of the pre-existing immunity” and current antibody-based therapies, experts advocate maintaining social distancing, masking, and restricting indoor contacts to in the saturation of health care ”.

The mice infected with Omicron had less severe clinical signs, with less weight loss, less viral load, both in the lower and upper respiratory tract, and less extensive inflammatory processes in the lungs.

Weight loss is of clinical severity in mouse models of COVID-19, noted the team, led by Eleanor Bentley of the University of Liverpool (UK).

Although mice infected with Omicron initially lost weight just as quickly, they recovered significantly between day 5 and 6 after infection and showed less extensive inflammatory processes in the lungs.

The rodents affected by Omicron had less severe pneumonia and their lungs “They appeared to be largely unchanged.”

In addition, . On the second day after infection, they had viral RNA levels one hundred times lower than those infected with the other two variants, and on the sixth day it was approximately 10 times higher in the Pango B and Delta mice.

Although it is still “very early” in the spread of the Omicron variant, it is beginning to infect patients, which is supported by the observations of this study, the team adds.

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