Last checked at 
(Adds CDC caution on South African data)
* AstraZeneca, Novavax say their shots protect from Omicron
* UK data suggests fewer hospitalisations than from Delta
* Don't extrapolate from similar SAfrican data -African CDC
* WHO also urged caution about drawing firm conclusions
* Omicron has spread fast, many countries under new curbs
By James Macharia Chege and Josephine Mason
LONDON, Dec 23 (Reuters) - Two vaccine makers said their
shots protected against the Omicron coronavirus variant as UK
data suggested it may cause proportionally fewer hospital cases
than the Delta strain, though public health experts warned the
battle against COVID-19 was far from over.
Similar encouraging evidence about hospitalisation rates had
emerged from South Africa on Wednesday, but the head of Africa's
main public health agency joined the World Health Organization
in cautioning that it was too soon to draw broad conclusions
about Omicron's virulence.
"Let's be careful not to extrapolate what we are seeing in
South Africa across the continent, or across the world," Africa
Centres for Disease Control (CDC) chief John Nkengasong told a
media briefing.
Coronavirus infections have soared across much of the world
as highly infectious Omicron has spread, triggering new
restrictions in many countries.
First identified last month in southern Africa and Hong
Kong, the variant is quickly becoming dominant in much of
western Europe including Britain, where daily new infections
have soared beyond 100,000.
But increases in hospitalisations and deaths in South Africa
and Britain since Omicron took hold appear to have been more
gradual, and AstraZeneca https://www.reuters.com/business/healthcare-pharmaceuticals/astrazeneca-shot-third-dose-works-against-omicron-study-2021-12-23
and Novavax https://www.reuters.com/business/healthcare-pharmaceuticals/novavax-says-covid-vaccine-boosts-response-omicron-variant-2021-12-22
have joined other vaccine manufacturers in saying
their shots protect against it.
University of Edinburgh https://www.reuters.com/business/healthcare-pharmaceuticals/scotland-reports-fewer-covid-19-hospitalizations-with-omicron-2021-12-22
researchers who tracked 22,205 Omicron patients said on
Wednesday the number who needed to be hospitalised was 68% lower
than they would have expected, based on the rate in patients
with Delta.
Imperial College London https://www.reuters.com/business/healthcare-pharmaceuticals/hospital-stay-risk-omicron-is-40-45-lower-than-delta-uk-study-2021-12-22
researchers said they saw evidence over the last two weeks of a
40%-45% reduction in the risk of hospitalisation for Omicron
relative to Delta.
'DON'T OVER-INTERPRET'
Raghib Ali, senior clinical research associate at the
University of Cambridge, said scientists had warned that, with
the surge in UK cases, even a small proportion of
hospitalisations could overwhelm the heathcare system.
However, the UK data was encouraging and "may help justify
the government's decision not to expand restrictions on social
gathering over Christmas in England", he said.
UK hospitalisations supported Wednesday's findings from
South Africa's National Institute for Communicable Diseases
(NICD).
However, the CDC's Nkengasong said the NICD data, suggesting
Omicron was 70%-80% less severe than Delta, should be
interpreted "with a lot of caution".
"This is early days and public health practice is local," he
said, adding that particular factors such as the young median
age of the South African population could be in play.
On Wednesday, the WHO's technical lead on COVID-19, Maria
van Kerkhove, had said data on Omicron was still too "messy" to
draw firm conclusions.
VACCINE HOPES
On Thursday, AstraZeneca said a three-course dose of its
COVID-19 vaccine offered protection against the variant, citing
data from an Oxford University lab study.
Findings from the study, yet to be published in a
peer-reviewed medical journal, match those from rivals
Pfizer-BioNTech, and Moderna.
The study on AstraZeneca's vaccine, Vaxzevria, showed that
after a three-dose course, neutralising levels against Omicron
were broadly similar to those against Delta after two doses.
Hours earlier, Novavax Inc said early data showed
its vaccine - authorised for use this week by the European Union
and WHO but yet to be approved by the United States - also
generated an immune response against Omicron.
As financial markets welcomed the signs that Omicron might
be less severe than feared, global shares extended a rally on
Thursday while safe-haven bonds and currencies eased.
Beyond western Europe, the Delta variant continued to
spread.
The coronavirus death toll in Russia, where officials said
this week they had detected only 41 Omicron cases, passed
600,000 on Thursday, Reuters calculations based on official data
showed, after a surge of infections linked to Delta.
Only the United States and Brazil have recorded more
coronavirus deaths.
The Chinese city of Xian, where no Omicron cases have been
detected, put its 13 million residents in a lockdown as the
daily count of domestically transmitted COVID-19 infections rose
for a sixth day running..
Interactive graphic tracking global spread of coronavirus:
open https://tmsnrt.rs/2FThSv7 in an external browser.
Eikon users can click https://apac1.apps.cp.thomsonreuters.com/cms/?navid=1063154666
for a case tracker.
(Reporting by Reuters bureaux around the world; Writing by John
Stonestreet; Editing by Catherine Evans, Edmund Blair and Mark
Heinrich)
