Last checked at 
(Adds detail throughout)
Dec 27 (Reuters) - European Union gave approval on Dec. 21
for the COVID-19 vaccine developed by Pfizer Inc and
BioNTech SE, the latest regulatory go-ahead for the
shot, while the United States authorised Moderna Inc's
vaccine on Dec. 19, the second for the country and the first for
the company worldwide.
The following is what we know about the race to deliver
vaccines to help end the coronavirus pandemic that has killed
more than 1.7 million people worldwide:
WHO IS FURTHEST ALONG?
U.S. drugmaker Pfizer and German partner BioNTech
are the COVID-19 vaccine trailblazers.
On Nov. 18, they became the first in the world to release
full late-stage trial data. Britain was the first to approve the
shot for emergency use on Dec. 3, followed by Canada on Dec. 9
and the U.S. Food and Drug Administration (FDA) on Dec. 11.
Several other countries including Saudi Arabia and Mexico have
also approved it.
The European Medicines Agency (EMA) approved the shot on
Dec. 21 and India is accelerating its review.
The World Health Organization could decide whether to give
its emergency use approval for the Pfizer candidate by the end
of the year as part of its COVAX programme aimed at providing
shots for poor- and middle-income countries.
WHO WILL APPROVE MODERNA NEXT?
Moderna became a close second to Pfizer in many countries
after it released a full data analysis for a late-stage trial on
Nov. 30 showing a 94.1% efficacy rate for its vaccine. Canada
approved the shot on Dec. 23 and the EMA will do so on Jan. 6.
WHO ELSE IS IN THE RUNNING?
Britain's AstraZeneca is seeking approval for its
vaccine in Britain after announcing interim late-stage trial
data on Nov. 23. It had an average efficacy rate of 70% and as
much as 90% for a subgroup of trial participants who got a half
dose first, followed by a full dose.
However, it is not clear how the regulator will deal with
the different dosages in the efficacy data in its assessment.
While India is conducting an accelerated review, it has asked
for more data. AstraZeneca is also in discussions with the EMA,
which is conducting a rolling review of the vaccine.
India is expected to make a decision on whether to approve
for the two full-dose regimen of the shot, which was shown to
tbe 62% effective in late-stage trials, soon. Its review does
not include the more effective dosage, with 90% efficacy which
was given to a small subgroup of volunteers in the trials.
U.S. drugmaker Johnson & Johnson plans to deliver
trial data in January 2021, teeing it up for U.S. authorization
in February if its shot is effective. It reduced the enrolment
target for its clinical trial to 40,000 volunteers from 60,000
on Dec. 9, potentially speeding results which are tied to how
quickly participants become infected.
U.S. firm Novavax is running a late-stage trial in
Britain with data due in the first quarter of 2021. It expects
to start a large-scale trial in the United States this month.
France's Sanofi and Britain's GlaxoSmithKline
, however, announced a setback on Dec. 11 in their
attempts to develop a vaccine. The drugmakers said it showed an
insufficient immune response in older people in mid-stage trials
and that they would start a new study in February.
WHAT HAPPENS IN THE TRIALS?
The companies typically test their vaccines against a
placebo - typically saline solution - in healthy volunteers to
see if the rate of COVID-19 infection among those who got the
vaccine is significantly lower than in those who received the
dummy shot.
HOW ARE VOLUNTEERS INFECTED?
The trials rely on subjects becoming naturally infected with
COVID-19, so how long it takes to generate results largely
depends on how pervasive the virus is where trials are being
conducted. Each drugmaker has targeted a specific number of
infections to trigger a first analysis of their data.
HOW WELL ARE THE VACCINES SUPPOSED TO WORK?
The World Health Organization ideally wants to see at least
70% efficacy. The FDA wants at least 50% - which means there
must be at least twice as many infections among volunteers who
received a placebo as among those in the vaccine group. The EMA
has said it may accept a lower efficacy level.
WHAT ABOUT RUSSIA AND CHINA?
While Pfizer's shot was the first to be rolled out following
the publication of full Phase III trial data, Russia and China
have been inoculating their citizens for months with several
different vaccines still undergoing late-stage trials.
Russia said on Nov. 24 its Sputnik V vaccine, developed by
the Gamaleya Institute, was 91.4% effective based on interim
late-stage trial results. It started vaccinations in August and
has inoculated more than 100,000 people so far.
India plans to make 300 million of the shots next year and
Argentina has given the greenlight for emergency use of the
shot, with some 300,000 doses arriving in the country on Dec.
24.
China launched an emergency use programme in July aimed at
essential workers and others at high risk of infection. It has
vaccinated about one million people as of mid-November using at
least three shots - two developed by the state-backed China
National Biotec Group (CNBG) and one by Sinovac Biotech.
Trial data on a COVID-19 vaccine developed by China's
Sinovac Biotech has varied: interim data from a late-stage trial
in Turkey showed its CoronaVac shot is 91.25% effective, while
researchers in Brazil say the shot was more than 50% effective.
The United Arab Emirates, meanwhile, said on Dec. 9 that one
of the CNBG vaccines was 86% effective based on interim results
from a late-stage trial in the Gulf Arab state.
(Editing by Caroline Humer, David Clarke, Mark Potter,
Josephine Mason and Louise Heavens)
