Two vaccine manufacturers said their shots offered protection against omicron, as British data

suggested it may result in proportionally fewer hospitalizations than the delta coronavirus variant, supporting conclusions reached in South Africa.

Coronavirus infections have soared across much of the world as the highly infectious omicron variant has spread, triggering new curbs in many countries. World Health Organization officials have stressed, however, that it is too soon to draw firm conclusions about its virulence.

First identified last month in Southern Africa and Hong Kong, the variant has quickly become dominant in Britain, where daily infections have soared beyond 100,000.

Preliminary data had indicated omicron was more resistant to vaccines developed before it emerged. But increases in hospitalizations and deaths in Britain since omicron took hold have been more gradual, researchers said.

University of Edinburgh researchers who tracked 22,205 patients infected with omicron said late on Wednesday that the number who needed to be hospitalized was 68 percent lower than they would have expected, based on the rate in patients with Delta.

Imperial College London researchers said they saw evidence over the last two weeks of a 40 percent to 45 percent reduction in the risk of hospitalization for omicron relative to delta.

AstraZeneca meanwhile said on Thursday that a three-course dose of its COVID-19 vaccine offered protection against the variant, citing data from an Oxford University lab study.

The study, yet to be published in a peer-reviewed medical journal, showed antibody levels against omicron after the booster shot were higher than antibodies in people who had been infected with and recovered naturally from COVID-19.

Hours earlier, Novavax Inc said early data showed its vaccine generated an immune response against omicron.

Novovax's two-dose, protein-based vaccine was authorized for use this week by European Union regulators and the WHO.

It has yet to be approved by the United States.

Global shares extended a recent rally on Thursday while safe-haven bonds and currencies eased as markets welcomed signs that the omicron variant of COVID-19 might be less severe than feared.

The UK data on hospitalizations was supported by a study released on Wednesday by South Africa's National Institute for Communicable Diseases (NICD).

However, NICD researchers included several caveats.

"It is difficult to disentangle the relative contribution of high levels of previous population immunity versus intrinsic lower virulence to the observed lower disease severity," they wrote.

The WHO's technical lead on COVID-19, Maria van Kerkhove, likewise said the UN agency did not have enough data to draw firm conclusions.

The data on omicron was still "messy," she told a briefing in Geneva on Wednesday.

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