Last checked at 
(Adds details on results of preliminary trial results on
AstraZeneca/Oxford University vaccine)
Nov 23 (Reuters) - Drugmakers and research centres around
the world are working on COVID-19 vaccines, with large global
trials of several of the candidates involving tens of thousands
of participants well underway.
The following is what we know about the race to deliver
vaccines to help end the coronavirus pandemic that has claimed
more than 1.34 million lives worldwide:
Who is furthest along?
U.S. drugmaker Pfizer Inc and German partner
BioNTech SE released final late-stage trial
data on Nov. 18 that showed their shot was 95% effective at
stopping COVID-19, the highest efficacy rate so far.
The companies are the first to publish final Phase III
efficacy and safety data and plan to apply for an emergency use
authorization (EUA) in the United States within days.
On Nov. 16, another U.S. pharmaceutical company, Moderna Inc
, released interim data showing that its vaccine worked
in a large, late-stage clinical trial with a 94.5% efficacy
rate.
Interim late-stage trial results for Russia's Sputnik V
vaccine published on Nov. 11 showed the shot is 92% effective.
AstraZeneca said on Monday its vaccine for the novel
coronavirus, developed by Oxford University, could be around 90%
effective without any serious side effects.
Johnson & Johnson says it is on track to deliver
data this year.
What happens in these trials?
The companies are testing 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.
What were pharma companies waiting for to release data?
The trials rely on subjects becoming naturally infected with
the coronavirus, 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.
Early in the trials, infection rates were low. With a surge
in infections around the globe in October and November, trial
participants became infected more quickly.
Pfizer's final results were based on 170 cases within its
trial involving more than 43,000 participants.
Moderna conducted its interim analysis after 95 participants
developed COVID-19, while Russia's examination was conducted
after 20 volunteers developed the disease.
AstraZeneca said its interim analysis was based on 131
infections among participants who received the vaccine and those
in a control group who were given an established meningitis
shot.
How well are the vaccines supposed to work?
The World Health Organization ideally wants to see at least
70% efficacy in trials. The U.S. Food and Drug Administration
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 European Medicines Agency has
said it may accept a lower efficacy level.
When will regulators rule on safety and efficacy?
Pfizer/BioNTech plan to submit an EUA application in the
United States within days. Moderna aims to file an application
in the coming weeks once it has the two months of safety data on
half the trial participants, as required by the U.S. Food and
Drug Administration. That should happen in the second half of
November.
That means an FDA decision is unlikely before December.
AstraZeneca said on Monday it will immediately prepare
regulatory submission of the data to authorities around the
world that have a framework in place for conditional or early
approval.
Regulators for Europe, the United Kingdom and Canada are
considering data as it becomes available. It is not clear when
companies will submit efficacy data or when the agencies would
make a decision.
Could these be the first widely available coronavirus
vaccines?
Yes, although China launched an emergency use programme in
July aimed at essential workers and others at high risk of
infection that has vaccinated hundreds of thousands of people.
At least four Chinese vaccines are far along including those
from China National Biotec Group (CNBG), CanSino
Biologics and Sinovac Biotech.
Sinovac said on Nov. 18 that mid-stage trial results showed
its CoronaVac vaccine triggered a quick immune response but the
level of antibodies produced was lower than in people who had
recovered from the disease.
CNBG has said it expects early trial data as soon as
November.
Russia has also given the Sputnik V vaccine developed by the
Gamaleya Institute to 10,000 members of the general population
considered at high risk of contracting the virus.
(Reporting by Carmel Crimmins and Carl O'Donnell; Additional
reporting by Julie Steenhuysen in Chicago, Michael Erman in New
York, Ludwig Burger in Frankfurt, Alistair Smout in London and
Polina Ivanova in Moscow; Editing by Caroline Humer, Edwina
Gibbs, David Clarke and Susan Fenton)
