Omicron is less severe than other Covid variants because it causes less lung damage, studies suggest
Omicron is less severe than previous Covid variants because it doesn’t cause as much damage to the lungs, a wave of studies has suggested.
A study by a consortium of American and Japanese scientists on hamsters and mice found that those infected with Omicron had less lung damage, lost less weight and were less likely to die than those who had other variants.
It found that mice infected with Omicron had a tenth less of the virus in their lungs compared to those with other variants.
The findings supported another paper by researchers at the University of Hong Kong, who studied human tissue in Omicron victims.
They found that Omicron grew significantly slower in 12 lung samples than previous virus strains.
Experts believe that the fact that the supermutant variant tends not to replicate as much in the lower parts of the lungs means it causes less significant damage, which could be behind its reduced severity.
Data from South Africa showed that Omicron patients are up to 80 percent less likely to end up in the hospital than those with Delta. And a similar study by the UK’s Health and Security estimated that the risk was 70 percent less.
Roland Eils, a computational biologist at the Berlin Institute of Health, said there is an emerging theme in the literature that suggests the variant tends to stay outside the lungs.
A study by a consortium of American and Japanese scientists on Syrian mice found that those infected with Omicron (right) had less lung damage, lost less weight and were less likely to die than those who had the Delta variant (left)
The findings supported another paper by researchers at the University of Hong Kong, who studied human tissue in Omicron victims (purple bars). They found that Omicron grew significantly slower in 12 lung samples than previous virus strains
Their study, which was not peer-reviewed and published on pre-print website medRxiv, found that of the 10,547 Omicron cases identified between Oct. 1 and Nov. 30, 261 (2.5 percent) were hospitalized. Hospitalized. By comparison, of the 948 non-Omicron cases over the same period — nearly all of them Delta, which was behind 95 percent of the cases before Omicron showed up — 121 people were hospitalized (12.8 percent). The researchers said it shows that those who caught Omicron had an 80 percent lower risk of needing hospital care.
Omicron IS milder, another study finds
People who receive Omicron are 80 percent less likely to be hospitalized than those who receive Delta, a large study from South Africa suggests.
The real-world analysis, of more than 160,000 people, showed that Omicron patients were also 70 percent less likely to be admitted to the ICU or on a ventilator compared to those with Delta.
South African doctors have been claiming for weeks that Omicron has mellowed since they raised the alarm on November 24, accusing the UK of panicking over Omicron.
But the National Institute for Communicable Diseases (NICD) researchers who conducted the study, which has not yet been peer-reviewed, said it still doesn’t answer whether Omicron is intrinsically weaker than Delta.
“It is difficult to disentangle the relative contribution of high levels of prior population immunity versus intrinsic lower virulence to the observed lower disease severity,” the researchers conclude.
It is believed that the built-up immunity from three previous waves of the virus and vaccines will do most of the heavy lifting to keep patients out of the hospital this time around.
It is believed that up to 70 percent of South Africans have previously had Covid and only about a quarter have been double vaccinated, with boosters not yet widely available.
He told the New York Times: “It’s fair to say that the idea is on the rise of a disease that manifests mainly in the upper respiratory tract.”
The first article, which was published as a pre-print on Research Gate and has not yet been peer-reviewed, looking at tissue samples in mice and hamsters.
Researchers assessed different areas of the lungs for mice infected with the Omicron variant, as well as other strains of the virus, including Delta.
They found that those infected with Omicron experienced much less severe symptoms.
And they were particularly struck by the way Syrian hamsters — a breed particularly susceptible to earlier strains — became less ill with the variant.
dr. Michael Diamond, a virologist at Washington University and a co-author of the study, said: “This was surprising, as every other variant has potently infected these hamsters.”
Meanwhile, Hong Kong scientists’ second study — also not peer-reviewed — looked at Omicron in people’s lung cells.
They found that the virus multiplies significantly less in the lower parts of the lung.
The researchers also studied cells in the bronchi — the tubes in the upper chest that supply air to the lungs — and found that the variant is 70 times more apparent in those cells.
They said the virus’ prevalence in higher areas of the chest makes it more transmissible because it is expelled more quickly in the breath.
But they said the lower levels in the lungs may also be behind the reduced severity suggested by parts of other studies.
They wrote: “These observations may suggest that Omicron may have reduced clinical severity, but such interpretations must be qualified because the severity of Covid-19 disease is determined not only by virus replication, but also by dysregulated innate immune responses.”
It comes after a UK analysis of more than a million cases of Omicron and Delta in recent weeks found the risk of hospitalization with the now dominant variant is about a third that of its predecessor.
Britain is experiencing a surge in Covid cases, driven by the highly transmissible variant, with a record daily infection rate of 189,846 yesterday.
As the number of hospital admissions starts to rise, the government says it thinks the new variant is milder than the Delta variant.
The number of patients requiring mechanical ventilation beds has also remained stable in December, in contrast to previous peaks in the pandemic.
The analysis was published by the UK Health Security Agency, after it partnered with the Cambridge University MRC Biostatistics unit to analyze 528,176 Omicron cases and 573,012 Delta cases.
It also found that vaccines can work well against Omicron.
‘In this analysis, the risk of hospitalization is lower for Omicron cases with symptomatic or asymptomatic infection after two and three doses of vaccine, with an 81 percent … reduction in the risk of hospitalization after three doses compared with unvaccinated Omicron- cases,” the UKHSA said.
Susan Hopkins, Chief Medical Adviser at UKHSA, said the analysis was in line with other encouraging signs about Omicron, but said the health service could still struggle with such high transmission rates.
“It is too early to draw any firm conclusions on the hospital’s seriousness, and the increased transmissibility of Omicron and the increasing cases among the over-60s in England means it remains highly likely that significant pressures will remain on the hospital in the coming weeks.” NHS will be shown,’ she said.