If the Omicron variant panics because of its very high transmissibility (three times more than Delta), it strikes less hard, according to the data currently available, coming from South Africa and the United Kingdom in particular. So far, the explosion of the pandemic has not translated into an overall increase in the death toll.
Although cases of COVID-19 have increased across the world, hospitalizations increased only slightly and Omicron appears to cause less severe disease than previous strains. The risk of being hospitalized would be 60% to 70% lower than with the Delta variant, according to a study conducted by the British health agency UKHSA. UK doctors are finding that their Omicron patients need mechanical ventilation less often and hospital stays are shorter.
“Increasing new evidence suggests that the Omicron variant of the coronavirus responsible for COVID-19 causes less severe symptoms than previous strains,” a World Health Organization official said on January 4. (WHO).
“Omicron is less dangerousalso assures Olivier Véran. It causes fewer acute respiratory distress syndromes, the need for resuscitation beds is lower than with the previous variants.”
Omicron does not descend into the lungs
The reason ? First, the fact that Omicron infects people who have already been vaccinated – and therefore better protected from serious forms – explains this lesser severity. But above all, several studies carried out by teams of researchers show that the Omicron variant multiplies less well in lung cells. In other words, it causes less damage in the lungs than previous strains of the coronavirus.
“We have more and more studies that suggest that Omicron infects the upper respiratory tract, unlike other strains, which could cause severe pneumonia,” explained Dr Abdi Mahamud, head of a team working on the management of the COVID-19 pandemic within the UN organization, while stressing that it could be “good news” .
Two studies carried out on mice and hamsters and relayed at the end of December by The New York Times show that the variant Omicron attacks the upper respiratory tract: the nose, throat and trachea. Unlike the initial strains, Alpha or Delta which also infected the lungs where they could trigger the famous cytokine storm, a particularly strong inflammatory reaction.
The report published on December 29 by Japanese and American scientists, shows that animals infected with Omicron show less lung damage, lose less weight and are less likely to die. Experiments carried out on hamsters – animals usually seriously ill when infected with the coronavirus – show astonishing results: their symptoms are much milder than with previous strains of the virus.
“It was surprising, because all the other variants strongly infected these hamsters,” Dr. Michael Diamond, a virologist at the University of Washington and co-author of the study, told the NYT.
There remains the question of the strong contagion
If these studies bring hope, they remain to be confirmed. Besides, it doesn’t explain why Omicron is so contagious. Sara Cherry, PhD, a virologist at the University of Pennsylvania, tells the NYT that this could be linked to the higher presence of virus in the saliva and nasal passages.
Anyway, even less dangerous, this variant could pose a real threat to countries in which the rate of vaccination coverage against COVID-19 remains low, the WHO said on Tuesday, January 4. Catherine Smallwood, an emergency manager at the WHO, explained that skyrocketing infection rates could have the opposite effect. “The more Omicron spreads, the more it is transmitted and the more it replicates, the more likely it is to generate a new variant“she clarified.
Sources:
- WHO
- Studies Suggest Why Omicron Is Less Severe: It Spares the Lungs, New York Times, December 31, 2021.
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