Last checked at 
* UK says 18-29 year olds should get other shots where
possible
* Oxford/AZ shot associated with rare cases of brain blood
clots
* Benefits outweigh the risks for vast majority, regulator
says
(Adds PM Johnson's reaction)
By Guy Faulconbridge, Kate Holton and Alistair Smout
LONDON, April 7 (Reuters) - Britain should give an
alternative to Oxford/AstraZeneca's COVID-19 vaccine to
under 30s where possible due to a "vanishingly" rare side effect
of blood clots in the brain, Britain's vaccine advisory
committee said on Wednesday.
Officials said the benefits of the shot continued to
outweigh its risks for the vast majority, after safety concerns
spurred over a dozen countries in recent weeks to suspend use of
the vaccine following reports linking it to a brain blood
clotting disorder. Britain has kept using the shot throughout.
Wei Shen Lim, chair of Britain's Joint Committee on
Vaccination and Immunisation (JCVI), said that based on the
available data and evidence, it was preferable for adults aged
under 30 with no underlying conditions to be offered an
alternative to the AstraZeneca vaccine where available.
He said that for younger people, where the risks of
hospitalisation were much lower, the risk/benefit calculation of
the Oxford/AstraZeneca shot meant others vaccines were
preferable.
"We are advising a preference for one vaccine over another
vaccine for a particular age group, really out of the utmost
caution, rather than because we have any serious safety
concerns," Lim said at a briefing.
He said people should continue to have a second dose of the
AstraZeneca shot if they had received a first dose.
June Raine, chief executive of the UK's MHRA medicine
regulator, said that over 20 million AstraZeneca vaccine doses
had been given by March 31, with 79 case reports of the side
effect and 19 deaths, all after first doses of the shot.
"This is a vanishingly rare, but sadly quite serious,
adverse event..., and you can't pick these kind of things up
until you have literally deployed tens of millions of doses of
vaccine," Deputy Chief Medical Officer Jonathan Van-Tam said.
He added that the move would have only a negligible impact
on the pace of Britain's vaccine rollout.
The rollout of Moderna's shot began on Wednesday,
while Britain is also deploying Pfizer's vaccine, and
Prime Minister Boris Johnson said the move on AstraZeneca would
not impact England's roadmap out of lockdown.
"As the regulators have said, this vaccine is safe,
effective and has already saved thousands of lives - and the
vast majority of people should continue to take it when
offered," he said.
GETTING FIRMER
The change to advice on Britain's vaccine rollout came after
its MHRA medicine regulator said the reports of rare brain blood
clotting were a suspected side-effect from the COVID-19 vaccine
developed by Oxford University and AstraZeneca.
MHRA chief Raine said the benefits of the shot outweighed
the risks for the vast majority, echoing an update from Europe's
medicine regulator also made on Wednesday.
Europe and Britain's medicine regulators have been
investigating small numbers of reports of brain blood clots,
known as cerebral venous sinus thrombosis (CVST), that have
occurred in combination with unusually low blood platelet levels
after people have been given the shot.
Munir Pirmohamed, chair of the Commission on Human
Medicines, said the link between cerebral blood clots, lower
platelets and the AstraZeneca vaccine was "getting firmer".
"Early evidence suggests that this constellation of symptoms
is caused by an immune response against platelets which allows
the platelets to then lead to clotting in different parts of the
body," he told a news conference.
"But what we don't have clearly is the link between the
vaccine and how the immune response becomes activated against
the platelets, and that's where the scientific work needs to go
on to identify what that link is."
(Reporting by Alistair Smout, Kate Holton, William James and
Paul Sandle; editing by James Davey, Guy Faulconbridge and Mark
Heinrich)
