UK researchers: Omicron infections seem less severe, leading to fewer hospitalisations

Two new studies suggest that omicron infections more often result in mild illness, compared with previous variants of the coronavirus, offering hope that the current surge may not be quite as catastrophic as feared, despite skyrocketing caseloads in much of the world.

The research, conducted in Britain and released Wednesday, indicated that people infected with the omicron variant are less likely to be hospitalized.

“What you’ve heard is a qualified good-news story,” Dr. Jim McMenamin, incident director for COVID-19 at Public Health Scotland, said at a news briefing at which he and colleagues presented data gleaned from Scottish hospitals.

While the results are heartening, McMenamin and other experts warned that hospitals could be flooded with omicron cases, because the variant transmits much more than previous ones.

McMenamin and his colleagues examined delta and omicron cases in November and December, looking at how many resulted in hospitalization. They reported that omicron infections are associated with a two-thirds reduction in the risk of hospitalization compared to the delta variant.

Also Wednesday, a team of researchers at Imperial College London looked at omicron and delta cases in the first two weeks of December and saw a smaller reduction in visits to hospitals.

Initial estimates suggest that compared with delta variant cases, individuals infected with omicron are 15% to 20% on average less likely to turn up in hospitals overall, and 40% to 45% less likely to be hospitalized for a night or more.

Paradoxically, though, the researchers also found the omicron virus is not that much less dangerous than delta.

Much of the reduction in severity is linked to the fact that omicron is better at infecting people who have already had a case of COVID. While so-called reinfection with omicron is much more common than with delta, these cases are less likely to put people in the hospital.

The difference between the English and Scottish results may be due in part to the data the scientists could study. For England, the Imperial College London team included people who just visited a hospital in addition to those who had to be put in a bed for more serious illness. The Scottish researchers looked only at hospital admissions.

Both teams of scientists cautioned that the results were preliminary. For one thing, omicron is still working its way through Britain and has yet to make much headway among older people, who might be at greater risk of hospitalization. “It’s important we don’t get ahead of ourselves,” McMenamin said.

But omicron still poses a serious risk to hospitals, the scientists warned, because cases are exploding so quickly. “We’re not at a place to treat this as a cold,” Azra Ghani of Imperial College said.

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