Omicron: Greater Infectiousness, More Hospitalizations

"Despite Omicron seeing the highest reported numbers of COVID-19 cases and hospitalizations during the pandemic, disease severity indicators, including length of stay, ICU admission, and death, were lower than during previous pandemic peaks."

U.S. Centers for Disease Control and Prevention

 

"There is support for both scenarios [that the Omicron variant really is a milder disease than Delta, or that it now encounters those with immunity from vaccination and old infections]."

"The emergence of another major variant of concern is highly probable as the virus has proven it can evolve to escape immunity in the current climate of infection."

Alex Sigal, virologist, South Africa

 

"It's replicating in places that cause less damage."

Suimit Chanda, infectious disease expert

 

"[Omicron entered a population] that had considerably more immunity than any previous SARS-CoV-2 variant had encountered."

"There must be a renewed push to vaccinate and boost those not yet protected, because Omicron is not necessarily intrinsically milder."

"[Matters would have been] much, much worse [with Delta]."

William Hanage, epidemiologist, Harvard University

"I think there's genuine good news about both intrinsic severity appearing to be slightly lower and immunity holding decently well against severe disease, far better than it is against infection."

"I just find myself a bit concerned about the oversimplified narrative that 'Omicron is milder', [or even worse], 'Omicron is mild'."

"The nuances matter here, I think."

Roby Bhattacharyya, infectious diseases physician, Harvard University

As much as medical science knows about the SARS-CoV-2 virus causing COVID-19, it doesn't know quite enough. Leaving too many questions and too few answers. But observation and greater understanding are all being acquired, bit by bit as the coronavirus continues its journey in its myriad mutations circulating world-wide, alerting anxious scientists time and again to new and perplexing variants.

 

Although there was a giant sigh of relief that circled the globe with the initial assurance that this form of the virus is milder, albeit more infectious than the Delta strain, there are still questions about whether, in actual fact, it is. There is the realization that its greater infectiousness means more illnesses leading inevitably to more hospitalizations, ICU treatment and deaths by virtue of sheer numbers of infection. All the more so among the as-yet-unvaccinated.

 

Compared to other variants, laboratory studies suggest that Omicron invades human cells differently than its predecessors, that once within human cells its presence is restricted for the most part to the upper respiratory tract, leaving it less likely to enter and spread in the lungs to cause more severe disease. Significantly reduced chances of severe disease developing and death for those infected with Omicron have been validated in studies.

 

 Photo by Getty Images

Researchers at Imperial College London were first to report in December that Omicron seemed to be less likely to hospitalize people or to ensure they're kept hospitalized for over a day, in comparison to people infected with the Delta strain. Since then, studies have emerged from South Africa, Southern California and the U.S. Centers for Disease Control and Prevention, finding that those with confirmed Omicron remain substantially less likely to be hospitalized, require oxygen therapy or mechanical ventilation - or die, in comparison with confirmed cases of Delta. 

Where the Omicron variant was first identified in South Africa the strain found a population with a substantial degree of immunity. Even so, Omicron excels in slipping around vaccine-produced immunity to cause breakthrough infections;'vaccines' effectiveness against hospitalization largely preserved, diminishing Omicron's impact, as a result of vaccine doses administered.

In comparison to those who have been doubly vaccinated, those who have not had any inoculation bear a five-fold higher risk of being hospitalized. Omicron has been the cause of over 2,400 deaths daily on average in the past week in the United States. Millions globally of new infections have been recorded from Omicron. The greater the number of infections, the more opportunities arise for the virus to mutate.

"Infection is the fuel that evolution has to bring us these new variants. We need to get infection numbers down."

"Those things [uncertainty over how long immunity from vaccination and exposure to Omicron lasts] will all affect how many new infections are happening per day, or per week, after this peak."

Caroline Colijn, epidemiologist, Simon Fraser University, British Columbia

Omicron is getting "an oversimplified narrative" that is it milder, but "the nuances matter here," says one infectious diseases doctor. Photo by Cole Burston/Reuters