Last checked at 
(Adds detail of trial, context)
* New trial data still shows lower efficacy than rival
vaccines
* Asia relying heavily on AstraZeneca to tackle pandemic
* Submission for U.S. approval could take few weeks
By Josephine Mason and Ben Blanchard
LONDON/TAIPEI, March 22 (Reuters) - AstraZeneca's COVID-19
vaccine performed better than expected in a major late-stage
trial potentially paving the way for its emergency authorization
in the United States and bolstering confidence in the shot after
numerous setbacks in Europe.
The drugmaker said on Monday that trials in Chile, Peru and
the United States found the vaccine, developed in conjunction
with Oxford University, was 79% effective in preventing
symptomatic COVID-19 and, crucially, posed no increased risk of
blood clots. It intends to request U.S. emergency authorization
in coming weeks.
More than a dozen European countries, including Germany and
France, had halted use of the AstraZeneca vaccine earlier this
month after some reports linked it to blood clots in a very
small number of people. They have since resumed inoculation
after a regional regulator said it was safe, but an opinion poll
on Monday showed Europeans remained sceptical over its safety.
Hailed as a milestone in the fight against the COVID-19
pandemic when it first emerged as a vaccine contender last year,
the AstraZeneca shot has since been dogged by confusion over its
efficacy, dosing regimen and possible side-effects as well as
supply setbacks in Europe, where the company has been at the
centre of a growing conflict between Brussels and London over
so-called 'vaccine nationalism'.
The latest data should help address some of those concerns,
analysts said. Based on more than 32,000 people, the trial was
larger and elderly volunteers featured more prominently than in
previous trial results from the UK which had prompted some
European countries to initially hold back using the AstraZeneca
shot on older people.
"It is clear this vaccine has very good efficacy (remember
that 60% was, prior to any trials being started, regarded as a
good target), and that this efficacy does not show a notable
decline at older ages," said Stephen Evans, Professor of
Pharmacoepidemiology at the London School of Hygiene & Tropical
Medicine
AstraZeneca shares were up over 1% in early London trading.
U.S. trials of rival vaccines from Pfizer and
Moderna, which are already being deployed in the United
States, have showed efficacy rates of around 95%.
But the AstraZeneca vaccine, which is already widely used
outside the United States, is seen as crucial to tackling the
spread of COVID-19 across the globe because it is easier and
cheaper to transport than rival shots.
"I have just finished getting the (AstraZeneca) injection,
there is no pain at the injection site, and there is no soreness
of the body," Taiwan Premier Su Tseng-chang told reporters as
the island launched its inoculation campaign on Monday.
British Prime Minister Boris Johnson received his first dose
of the AstraZeneca COVID-19 vaccine on Friday, saying he "did
not feel a thing."
And French President Emmanuel Macron has said he would take
the AstraZeneca vaccine if that's what was offered after
previously being quoted as saying the shot was
"quasi-ineffective".
HEADWINDS
The AstraZeneca vaccine has already been granted a
conditional marketing authorisation or emergency use in more
than 50 countries, spanning four continents.
But it has yet to be approved in the United States, where
President Joe Biden is stepping up the federal response to the
pandemic by expanding testing, ramping up vaccinations and
boosting production.
University of Oxford professor Sarah Gilbert told BBC radio
that work to prepare a submission for Emergency Use
Authorization in the United States will take a few weeks. A
company spokesman said the filing would likely be in the first
half of April.
The American trial results have not yet been reviewed by
independent researchers.
If the AstraZeneca vaccine gets U.S. approval, it would be
the fourth after Pfizer, Moderna and Johnson & Johnson.
It uses a modified version of a chimpanzee common cold virus
to teach the human body to make proteins from the novel
coronavirus to generate an immune response and prevent
infection.
Scepticism over the shot started last year when the British
drugmaker and Oxford University published data with different
efficacy readings due to a dosing measurement error. Later
analysis suggested the dosing interval rather than the amount of
dose administers was responsible for the difference.
Many Asian countries heavily rely on the AstraZeneca vaccine
to end the pandemic, as the shot is being used in inoculation
programmes in Australia, South Korea, the Philippines, Vietnam,
Thailand, and India.
Some states in India, which has the highest coronavirus
caseload after the United States and Brazil, are seeking to
accelerate the vaccination drive, as the country reported its
most COVID-19 cases and deaths in months on Monday.
As vaccine demand rises at home, top producer the Serum
Institute of India has delayed further shipments of the
AstraZeneca shot to Brazil, Britain, Morocco and Saudi Arabia.
.
In Europe, meanwhile, the European Union has threatened to
block exports of COVID-19 vaccines to Britain to safeguard
scarce doses for its own citizens, with Commission President
Ursula Von der Leyen saying the epidemiological situation was
worsening.
(Additional reporting by Pushkala Aripaka and Muvija M in
Bengaluru, Ludwig Berger in Frankfurt, Krishna Das in New Delhi,
Colin Packham in Canberra, Stanley Widianto in Jakarta, Sangmi
Cha in Seoul, Neil Jerome Morales in Manila and Kate Kelland in
London; Writing by Miyoung Kim and Barbara Lewis; Editing by Ana
Nicolaci da Costa and Carmel Crimmins)
