Two studies published in the United Kingdom on Wednesday found that Covid infections with Omicron are less likely to result in hospitalisation than those with Delta, confirming a trend previously identified in South Africa.
Experts cautiously praised the preliminary investigations, one from Scotland and the other from England, but cautioned that any benefit in milder results could be outweighed by the new strain’s increased infectiousness, which could lead to more overall severe cases.
“We’re saying this is qualified good news,” Jim McMenamin, a co-author of the Scottish study, told reporters on the phone. “Qualified because these are early observations, they’re statistically significant, and we’re seeing a reduced risk of hospitalisation.”
The Scottish study looked at Covid instances from November and December, separating those caused by Delta from those caused by Omicron.
It discovered that “as compared to Delta, Omicron is related with a two-thirds reduction in the likelihood of Covid-19 hospitalisation,” as well as demonstrating that a booster immunisation provided significant further protection against symptomatic infection.
The study was small, and no one under the age of 60 was hospitalised at the time, but the authors stated they used statistical methods to account for these shortcomings.
The second study, from England, indicated that Omicron had a 20-25 percent lower rate of any hospitalisation compared to Delta, and a 40-45 percent lower rate of hospitalizations lasting one night or longer, or “admissions.”
Because the Scottish study only looked at admissions, this could explain for some of the discrepancy.
“While the lowered likelihood of hospitalisation with the Omicron variant is reassuring, the risk of infection remains extremely high,” said Azra Ghani of Imperial College London, who co-authored the England study.
“Vaccines continue to provide the highest protection against illness and hospitalisation with the addition of the booster dosage.”
Although neither study has been peer reviewed, it adds to the growing body of knowledge about Omicron illness outcomes.
It’s uncertain if Omicron’s lower rate of severe cases is due to the variant’s features, or whether it appears milder because it’s encountering individuals with higher immunity from prior infection and immunisation.
“This news somehow doesn’t detract from the exceptional spread of this variant from across population, and the fact that even a small proportion of the population requiring hospital care for COVID could become a very substantial percentage indeed if the community attack rate continues to worsen,” said Penny Ward, a professor of pharmaceutical medicine at King’s College London who was not involved in the research.